,transcriber's ,note3 ,text delimited by equal signs is bold1 ,text delimited by uderscores is italic4 ,a character preceded by a caret is superscript1 multiple characters enclosed in braces and preceded by a caret are likewise1 superscript4 ,text delimited by braces and underscores is subscript4 ,,attack ,,of ,,fortified ,,places4 ,,including ,,siege-,,works1 ,,mining1 ,,and ,,demolitions4 ,,prepared ,,for ,,the ,,use ,,of ,,the ,,cadets ,,of ,,the ,,united ,,states ,,military ,,academy4 ,,by ,,james ,,mercur1 ,professor of ,civil and ,military ,engineering at the ,united ,states ,military ,academy1 ,west ,point1 ,n4 ,y4 ,,first ,,edition4 ,,first ,,thousand4 ,,new ,,york ,,john ,,wiley ,,sons1 #ec ,,east ,,tenth ,,street4 #ahid4 ,,copyright1 #ahid1 ,,by ,,james ,,mercur1 ,west ,point1 ,n4 ,y4 ,right of ,translation ,reserved4 ,,preface4 ,in this work an attempt has been made to give in outline the best modern methods of attack upon a fortified position by assault1 surprise1 blockade1 or siege2 and also the detailed constructions of those types of trenches1 batteries1 magazines1 etc41 etc41 which seem best suited to resist the fire of modern cannon1 and to afford cover to a besieging force4 ,it is not supposed that these types will be exactly copied in all cases of actual practice1 but that a wise discretion will be used in modifying or combining them when necessary or desirable4 ,the constructions given are standard types1 which have grown up by combining the suggestions and the experience of the military engineers of all civilized nations4 ,in selecting them ,i have drawn freely upon the textbooks of the schools of military engineering at ,chatham1 ,fontainebleau1 ,vienna1 and ,berlin1 as well as upon that of the late ,professor ,mahan1 and the manuals of ,duane and ,ernst4 ,the standard work of ,gumpertz and ,lebrun is frequently referred to in 8,military ,mining02 and ,i am also under obligations to ,general ,h4 ,l4 ,abbot1 ,corps of ,engineers1 for the use of his unpublished notes on the experimental mines at ,willett's ,point1 and the result of his experiments upon the mining effects of shells charged with different explosives4 ,j4 ,m4 ,,west ,,point1 ,n4 ,y41 ,october1 #ahid4 ,,introduction4 ,modern wars have been marked by sharp aggressive campaigns and great battles in the open field1 with few close and long-continued sieges4 ,the subject of siege-works has therefore attracted less popular attention than was formerly devoted to it4 ,fort ,wagner1 ,vicksburg1 ,petersburg1 ,strasburg1 ,belfort1 ,paris1 ,plevna1 and ,gok ,tp have shown1 however1 that at their respective dates regular siege and mining operations were necessary to reduce either permanent or field fortifications1 if well equipped and defended4 ,the volume of fire delivered by the small arms and machine guns now in use has made an open assault upon a well-supplied and well-defended parapet1 under ordinary circumstances1 a hopeless undertaking1 and has necessitated more deliberate methods of attack4 ,the increased accuracy and penetration of modern cannon have rendered obsolete many of the older methods of making regular approaches4 ,the newer constructions described herein1 while giving greater protection to the attack1 are in general slower in their advance than those previously used4 ,this seems1 however1 to be an unavoidable evil1 which is mitigated only by taking advantage of every opportunity for rapid advance offered by the errors of the defence4 ,it is not to be inferred that light field works and lines will in the general case require for their attack a system of regular approaches2 but trenches and saps may be necessary for placing a battery or parapet in a commanding position or one favorable for enfilade1 or for giving a covered approach over an exposed ridge2 and their frequent employment may be expected on future fields4 ,the destructive effect of grenades and ,coehorn shells charged with high explosives will doubtless in many cases check or stop the advance of saps and trenches1 and necessitate the use of blinded approaches or mining-galleries in stubbornly contested sieges4 ,the successful application of mines at ,gok ,tp will doubtless lead to their future employment under similar circumstances4 ,in the close attack upon a shielded casemate or disappearing turret their use seems a necessity1 and when these defences are founded on rock or massive concrete foundations1 tunnelling operations by drilling and blasting will be required4 ,when practicable they will be expedited by the use of power-drills driven by electricity4 ,it seems hardly necessary to add1 that in sapping and mining operations1 as in all other branches of military engineering1 all new and improved inventions and methods which are applicable to the work on hand will be used1 as a matter of course4 ,the thickness of cover given in the text is based upon the penetrations of the hostile projectiles4 ,for ready reference the maximum penetrations obtained in experimental firing up to this date 7#ahid7 are given herewith1 viz43 ,service bullets1 copper or ,german-silver jacket1 of #f4e to #h mm4 calibre1 initial velocity from #bjjj to #beej f4 s43 ,at ,muzzle4 #ajj yds4 #ijj yds4 #bjjj yds4 #bgcj yds4 ,inches4 ,inches4 ,inches4 ,inches4 ,inches4 ,pine wood #cj to #ej #ca to #ce #aj to #ad #d4d ,seasoned oak wood #d to #h #a4ah ,untamped clay #fj to #gh ,light sand #h ,at #ejj yds #ag inches4 #ccj yds4 #ddj yds4 #hhj yds4 #bjjj yds4 ,inches4 ,inches4 ,inches4 ,inches4 ,sand and earth #cf #cc #bj #ad #d ,steel and iron plate #j4ca to #j4ch #j4bh #j4bd ,brick masonry #d ,ice #fc ,special steel-coated bullets1 cal4 #j4bf and #j4cj3 ,pine wood #ee ,oak wood1 seasoned #af to #bd ,beech wood #bc to #cj ,sand #ad ,special steel-coated bullets1 cal4 #j4bcf1 vel4 #bfjj f4 s4 ,pine wood #fb ,french authorities give a muzzle penetration of #ab mm4 #j4dgc in iron plates for the ,lebel bullet4 ,no published experiments confirm this4 ,but few experiments seem to have been made to determine the penetration of the projectile of field and siege guns into earth1 and the published data are very meagre and unsatisfactory4 ,the ,german ,engineer's ,handbook 7,pionier ,taschenbuch1 #ahib7 prescribes the following thicknesses of parapets for cover against small-arm and cannon fire1 viz43 ---------------------------------------- ------------------------------------ ,shrapnel and ,material4 ,small ,arm4 ,splinters4 ,field-guns4 ,siege-guns4 ---------------------------------------- ------------------------------------ ,earth1 sandy #cj #bj to #dj #af' #bc' ,turf and marshy earth #fj ,wood #cd to #dj ,brick masonry #ae ,brick masonry1 single shot #c' #d ,two steel plates each #j4cb #j4fd ,packed snow #f' #bf' ,sheaves of grain #af' ---------------------------------------- ------------------------------------ ,english authorities report craters of #ba feet length and #h feet depth blown out from an earth parapet by a single #bjj-lb4 #h-;in4 howitzer shell4 ,they also state that the projectile of the pneumatic dynamite gun has penetrated #dj feet of earth4 ,owing to the rapid development of ordnance the current scientific and military periodicals are in general the only source from which the latest results in penetration1 etc41 can be obtained4 ,,contents4 ,,attack ,,of ,,fortified ,,places4 ,,page ,,introduction4 v ,,chapter ,i4 ,,the ,,attack ,,without ,,the ,,use ,,of ,,regular ,,approaches4 ,,article #a4 ,blockade1 #a #b4 ,surprise1 #b #c4 ,defence against ,surprise1 #d #d4 ,assault1 #d #e4 ,dispositions for an ,assault1 #e #f4 ,defence against an ,assault1 #g #g4 ,bombardment1 #h #h4 ,defence against a ,bombardment1 #aj ,,chapter ,,ii4 ,,siege ,,or ,,attack ,,by ,,regular ,,approaches1 ,,preliminary ,,constructions1 ,,definitions1 ,,etc4 #i4 ,siege1 ,progress of1 #ab #aj4 ,tools and ,appliances1 #ac ,,chapter ,,iii4 ,,trenches1 ,,approaches1 ,,parallels1 ,,saps1 ,,splinter-,,proofs ,,and ,,passage ,,of ,,the ,,ditch4 #aa4 ,trenches1 #ae #ab4 ,parallels1 #ae #ac4 ,approaches1 #af ,,tracing ,,and ,,constructing ,,parallels ,,and ,,approaches4 #ad4 ,tracing ,parallels1 #ag #ae4 ,tracing ,approaches1 #ah #af4 ,posting ,working ,parties1 #ah ,,execution ,,of ,,parallels ,,and ,,approaches4 #ag4 ,simple ,trench and ,flying ,sap1 #bj #ah4 ,construction by ,simple ,trench1 #bj #ai4 ,construction by ,flying ,sap1 #bb ,,splinter-,,proof ,,cover4 #bj4 ,splinter-proofs1 #bc #ba4 ,bomb-proofs1 #be ,,sapping4 #bb4 ,definitions1 etc41 #bg #bc4 ,full ,sap1 #bh #bd4 ,organization and ,duties of ,detachment1 #bh #be4 ,driving the ,sap1 #bh #bf4 ,breaking out a ,sap from a ,parallel1 #cj #bg4 ,circular ,place of ,arms1 #ca #bh4 ,shallow ,sap1 #ca #bi4 ,overground ,approaches1 #ca #cj4 ,double ,sap1 #cb #ca4 ,execution of the ,double ,sap1 #cb #cb4 ,changing ,direction of the ,double ,sap1 #cc #cc4 ,breaking out a ,double ,sap from a ,parallel1 #cc #cd4 ,traversed ,sap1 #cc #ce4 ,traverse by ,blinded ,sap1 #ce #cf4 ,crowning the ,covered ,way1 #ce #cg4 ,trench ,cavalier1 #cf #ch4 ,former ,methods of ,sapping1 #cf #ci4 ,passage of the ,ditch1 #cg #dj4 ,a ,wet ,ditch without ,current1 #ch #da4 ,a ,wet ,ditch with ,current1 #dj ,,chapter ,,iv4 ,,batteries1 ,,observatories1 ,,and ,,magazines4 #db4 ,batteries ,defined1 etc41 #db #dc4 ,general ,requirements of ,siege-batteries1 #db #dd4 ,construction of ,batteries for ,field-guns1 #dc #de4 ,batteries for ,siege-guns and ,howitzers1 ,elevated and ,sunken1--,general ,considerations1 #dd #df4 ,screens1 #de #dg4 ,exposed ,sunken ,battery1 #df #dh4 ,tracing the ,battery1 #dg #di4 ,constructing the ,central ,passage and ,splinter-proof1 #dh #ej4 ,constructing the ,battery1 #di #ea4 ,alternative ,construction1 #ej #eb4 ,splinter-proofs 7additional71 #ej #ec4 ,sunken ,battery in a ,parallel1 #ea #ed4 ,battery behind ,crest of a ,hill1 #ec #ee4 ,batteries on ,sloping ,ground1 #ec #ef4 ,embrasures1 #ec #eg4 ,observatories1 #ed #eh4 ,drainage1 #ee #ei4 ,mortar-batteries1 #ee #fj4 ,magazines1 #eg #fa4 ,cover for ,magazines1 #eh #fb4 ,location of ,magazines1 #eh #fc4 ,construction of a ,magazine subject to ,direct ,fire only1 #fj #fd4 ,manner of ,executing the ,work1 #fa #fe4 ,mined ,magazines1 #fa #ff4 ,elevated ,magazines1 #fb #fg4 ,precautions against ,dampness1 #fc ,,chapter ,v4 ,,siege ,,operations4 #fh4 ,the ,attack--,successive ,steps1 #fd #fi4 ,the ,first ,period1 #fe #gj4 ,the ,investment1 #fe #ga4 ,bringing ,up and ,posting the ,besieging ,force1 #fg #gb4 ,fortifying the ,camps1 ,parks1 etc41 #fh #gc4 ,distance of the ,line of ,investment from the ,works1 #gj #gd4 ,strength and ,composition of the ,besieging ,force1 #gj #ge4 ,the ,point of ,attack1 #gc #gf4 ,first ,artillery ,position1 #ge #gg4 ,opening ,fire1 #gf #gh4 ,plan of ,attack1 #gh #gi4 ,the ,first ,parallel1 #gh #hj4 ,opening the ,parallel1 #hj #ha4 ,the ,second ,artillery ,position1 #ha #hb4 ,counter-batteries1 #hb #hc4 ,enfilading-batteries1 #hb #hd4 ,breaching-batteries1 #hc #he4 ,batteries of ,rifled ,mortars and of ,howitzers for ,vertical ,fire1 #hc #hf4 ,opening and ,conduct of ,fire from ,second ,artillery ,position1 #hc #hg4 ,musketry ,fire1 #hd #hh4 ,the ,advance from the ,first ,parallel1 #hd #hi4 ,the ,second ,parallel1 #he #ij4 ,the ,third ,period1 #hf #ia4 ,capture and ,crowning of the ,covered ,way1 #hg #ib4 ,breaching the ,scarps and ,counter-scarps1 #hh #ic4 ,capture and ,crowning of the ,breach1 #hi #id4 ,the ,attack by ,sap1 #ia #ie4 ,additional ,operations ,necessary in the ,attack of an ,intrenched ,camp1 #ia #if4 ,occupation of a ,conquered ,place1 #ic #ig4 ,vauban's ,maxims1 #id #ih4 ,journal of the ,attack1 #ig ,,chapter ,,vi4 ,,the ,,defence4 #ii4 ,preliminary ,considerations1 #ih #ajj4 ,garrison1 #ii #aja4 ,armament1 #ajj #ajb4 ,ammunition1 ,provisions and ,supplies1 #aja #ajc4 ,sanitation and ,hygiene1 #aja #ajd4 ,preparations for ,defence1 #aja #aje4 ,defence during the ,first ,period1 #ajc #ajf4 ,opening of ,artillery ,fire by the ,defence1 #ajd #ajg4 ,defence during the ,bombardment and ,assault1 #aje #ajh4 ,defence during the ,second ,period of the ,siege1 #ajf #aji4 ,defence during the ,third ,period of the ,siege1 #ajg #aaj4 ,the ,capitulation1 #aji #aaa4 ,journal of the ,defence1 #aaj ,,chapter ,,vii4 ,,parks1 ,,depots1 ,,shelters ,,and ,,huts1 ,,kitchens1 ,,ovens1 ,,sinks1 ,,latrines1 ,,water-,,supply1 ,,etc4 ,,article ,,page #aab4 ,parks and ,depots1 #aaa #aac4 ,shelters and ,huts1 #aac #aad4 ,kitchens and ,ovens1 #aad #aae4 ,latrines1 ,sinks1 etc41 #aae #aaf4 ,water-supply1 #aaf ,,part ,,ii4 ,,military ,,mining4 ,,chapter ,i4 ,,nomenclature ,,and ,,theory4 ,,article ,,page #a4 ,definitions1 #aai #b4 ,theory of ,explosion1 #abj #c4 ,form and ,volume of ,crater1 #aba #d4 ,relation between ,volume of ,crater and ,charge1 #abb #d4 ,miner's ,rule1 #abb #e4 ,charge for ,one ,cubic ,yard1 #abc #f4 ,rule for ,common ,mines in ,ordinary ,earth1 #abd #g4 ,overcharged and ,undercharged ,mines1 #abe #g4 ,deduction of ,formula for ,charge1 #abe #h4 ,relation between ,charges of ,common and ,over- or ,undercharged ,mines1 #abg #h4 ,charge to ,produce a ,camouflet1 #abh #i4 ,radius of ,rupture1 #abh #aj4 ,theoretical ,value of ,radius of ,rupture1 #abi #aa4 ,values ,adopted by ,english ,authorities1 #aca #ab4 ,theoretical ,value ,too ,small1 #aca #ac4 ,high ,explosives1 #aca #ad4 ,experimental ,determinations1 #aca #ae4 ,choice of ,explosives1 #acb #af4 ,probable ,advantage of ,high ,explosives for ,overcharged ,mines1 #acc #ag4 ,relative ,advantages and ,disadvantages of ,gunpowder and ,high ,explosives1 #acd ,,chapter ,,ii4 ,,practical ,,operations ,,and ,,details4 #ah4 ,tools and ,appliances1 ,description of1 #acf ,,galleries ,,and ,,shafts4 #ai4 ,dimensions of ,galleries and ,shafts1 #ach #bj1 #ba4 ,shaft and ,gallery ,linings1 #aci #bb4 ,shaft and ,gallery ,frames1 #adj #bc4 ,dimensions of ,pieces of ,frames1 etc41 #ada #bd4 ,relative ,advantages of ,cases and ,frames1 #ada #be-bh4 ,sinking ,shaft by ,frames and ,sheeting1 #ada #bi4 ,precautions ,needed1 #add #cj4 ,partly-lined ,shafts1 #ade #ca4 ,driving a ,gallery with ,frames and ,sheeting1 #ade #cb4 ,use of ,false ,frame1 #adf #cc4 ,use of ,shield1 #adg #cd4 ,inclined ,galleries1 #adg #ce4 ,position of ,frames1 #adh #cf4 ,partly-lined ,galleries1 #adh #cg-ci4 ,change of ,direction of ,galleries with ,frames and ,sheeting1 #adh #ch4 ,change of ,slope1 of ,galleries1 #adi #dj1 #da4 ,returns1 #aej #db1 #dc4 ,maps and ,drawings1 #aea #dd1 #de4 ,sinking a ,shaft with ,cases1 #aeb #df-dh4 ,driving a ,gallery with ,cases1 #aec #di4 ,change of ,direction of ,galley ,lined with ,cases1 #aed #ej1 #ea4 ,change of ,slope1 #g ,galleries ,lined with ,cases1 #aee #eb4 ,shafts la ,boule1 #aef #ec-ee4 ,blinded ,galleries1 #aef #ef4 ,rate of ,advance of ,galleries1 #aeg ,,ventilation ,,of ,,mines4 #eg4 ,sources of ,deleterious ,gases1 #aeh #eh4 ,ventilation by ,forcing in ,air1 #aei #ei4 by ,exhausting ,air1#aei #fj4 by ,assisting ,natural ,ventilation1 #afj #fa4 by ,use of ,masks1 etc41#afj ,,mine-,,chambers4 #fb4 ,form1 ,size1 and ,location of ,chambers1 #afj ,,loading ,,and ,,firing ,,mines4 #fc4 ,preparing the ,charge1 #afa #fd4 ,distribution of ,fuses in ,charge1 #afa #fe4 ,character and ,construction of ,fuses1 #afc #ff-fh4 ,electric ,fuses1 #afc #fi4 ,placing the ,fuses in the ,charge1 #afd #gj4 ,the ,fuzes in ,frozen ,dynamite1 #afe #ga4 ,placing the ,charge1 #afe #gb4 ,tamping ,mines1 #aff #gc4 ,firing ,mines1 #aff ,,camouflets ,,by ,,boring4 #gd4 ,in ,favorable ,soil1 #afg #ge4 ,in ,stony ,soil1 #afh ,,chapter ,,iii4 ,,organization ,,and ,,tactics ,,of ,,mines4 #gf4 ,organization of ,mines1 #afi #gg4 ,the ,attack1 #afi #gh4 ,the ,lodgment1 ,galleries1 ,transverses1 ,listening-galleries1 etc41 #agj #gi4 ,avoid ,exposing a ,flank1 #aga #hj4 ,use ,overcharged ,mines1 #aga #ha4 ,the ,defence1 #aga #hb4 ,conditions to be ,fulfilled1 #aga #hc4 ,system of ,galleries ,used1 #agb #hd4 ,use ,undercharged ,mines1 #agb #he4 ,shaft ,mines1 #agb ,,mine ,,tactics4 #hf4 ,tactics ,derived from ,results of ,experience1 #agb #hg4 ,todleben's ,rules1 #agc #hh4 ,the ,attack1 #agc #hi4 ,the ,defence1 #agd #ij4 ,advantage ,lies with ,besieger1 #agf ,,breaching ,,by ,,mines4 #ia4 ,preparation of ,wall ,location and ,size of ,charge1 #agf #ib4 ,galleries behind ,counter-scarps1 #agg #ic4 ,galleries through ,scarp1 #agg ,,chapter ,,iv4 ,,blasting ,,and ,,demolitions4 #id-ig4 ,definitions2 ,tools and ,appliances1 #agh #ih4 ,tamping ,blasts1 #agi #ii4 ,determining the ,charge1 #agi #ajj4 ,precautions1 #ahj ,,demolitions4 #aja4 ,deliberate ,demolitions1 #ahj #ajb4 ,hasty ,demolitions1 #aha #ajc4 ,houses and ,magazines1 #aha #ajd4 ,walls1 #aha #aje4 ,stockades1 #ahb #ajf4 ,bridges1 #ahb #ajg4 ,tunnels1 ,canal-locks1 etc41 #ahc #ajh4 ,railroads1 #ahc #aji4 ,rolling-stock1 #ahd #aaj4 ,excess of ,explosive to be ,used1 #ahd ,,attack ,,of ,,fortified ,,places4 ,,chapter ,i4 ,,the ,,attack ,,without ,,the ,,use ,,of ,,regular ,,approaches4 #a4 ,a fortified position may be taken by blockade1 surprise1 assault1 bombardment1 or siege4 ,a blockade consists in so surrounding a place and closing its communications as to keep the garrison from receiving reinforcements1 provisions1 and supplies sufficient to enable it to continue the defence and to avoid starvation4 ,the object of the attacking force is1 in general1 to completely close all communications between the garrison and the exterior2 but this is not always possible1 nor is it necessary in all cases1 since such obstruction of communications as will reduce the incoming supplies below the necessary expenditures of the garrison will ultimately exhaust its stores4 ,an efficient blockade1 continued long enough1 will consequently reduce any place4 ,whether it is advisable to attempt to reduce a place by blockade will depend upon the time which will probably be taken in its reduction1 the force required for surrounding it1 and repelling sorties from the interior or beating back a relieving army1 and the expense in men and materials of taking the work by other methods4 ,blockades are more effective in reducing cities and towns than in taking places occupied only by a military garrison1 since the presence of a large number of non-combatants in a place rapidly exhausts its store of provisions1 renders epidemics more likely to break out1 and by the suffering and misery resulting demoralizes the garrison1 unnerves the commander1 and eventually causes its fall4 ,this justifies the apparent harshness of not allowing non-combatants to leave a beleaguered place4 ,the steps necessary for establishing the blockade are identical with those taken for the investment in a regular siege and will be described hereafter4 ,the capture of ,paris in #ahgj-ga is one of the most recent and striking examples of a blockade on a large scale4 ,,surprise4 #b4 ,a sudden and unexpected attack made upon a garrison unprepared to receive it is called a surprise4 ,formerly these were of not infrequent occurrence1 but with modern means of communication and methods of warfare they can hardly be looked for1 except in small affairs1 where1 through the weakness or exhaustion of a garrison or the incapacity of its commander1 the necessary and ordinary precautions for their prevention are impracticable or are neglected2 or where they are brought about through treachery in the garrison1 by which the gates are opened to the attack4 ,probably in the majority of cases attempts at surprise will be detected and defeated2 but as a success is usually valuable far in excess of the losses suffered in its execution1 promising opportunities for their trial should not be neglected4 ,surprises1 when thought possible1 are undertaken under the cover of night1 fog1 or severe storms4 ,the tactical disposition of the troops is similar to that used in open assault1 the columns being preceded by ladder-parties for scaling walls1 engineers for blowing down barriers1 etc41 etc41 according to the nature of the case1 and followed by a large reserve which is designed to hold any points captured by the advancing columns4 ,it is usually considered best to make simultaneous attacks at several points1 in order to confuse and divide the defence1 holding the main reserve nearest to the column which is expected to succeed2 but making provision also for promptly and fully supporting any other party which may have forced an entrance into the work4 ,an entrance secured1 consecutive points should be occupied and held1 preserving communication between them1 and avoiding too great dispersion of the troops1 until a foothold is gained which can in all probability be held against the defence4 ,after this greater boldness may be used in attacking important points within the place4 ,the complete capture of the work and its garrison cannot ordinarily be expected1 however1 until daylight allows the systematic movement of the attack throughout the place4 ,in case of failure1 any captured gate must be held if possible until all the troops have retreated through it and are covered by the reserves4 ,,defence ,,against ,,surprise4 #c4 ,the measures necessary to guard a fortified place against surprise are of two classes4 ,first1 for its prevention1 by use of all the usual outposts and interior guards1--the organization and duties of which need not be repeated here1--and of telegraphic and other signals and communications with the surrounding country by which the approach and movements of any attacking force may be made known before it comes near the work4 ,second1 for its repulse1 by so training and disciplining the garrison that1 upon the alarm being given1 the parapets1 batteries1 etc41 will be manned and all defensive measures will be taken before the assaulting body can enter the work4 ,this will be accomplished by so thoroughly drilling the garrison in its duties that each man will go at once to his proper station fully equipped for his duties at any hour day or night1 without confusion or unnecessary excitement4 ,the subsequent measures are the same as for resisting any other assault4 ,,assault4 #d4 ,by an assault is meant an open attack upon a position by troops in line or column4 ,formerly it was recommended to make assaults at early dawn1 in order to have the increasing daylight for securing the results of victory2 more recently night attacks have been more strongly advocated in order to diminish the losses from the fire of the defence while making the attack1 and the still greater ones which follow a repulse when1 the fire of the supports and reserves of the attack being suspended for fear of injuring the retreating troops1 the defence pours upon the latter the full close and deadly fire of all its arms4 ,whether the advantages of a night attack more than counterbalance the dangers resulting from the confusion due to darkness is1 however1 a question not yet settled4 ,open assaults upon fortified positions1 well manned and armed1 have1 since the introduction of firearms1 been considered the most bloody1 uncertain1 and frequently the most unjustifiable operations in war4 ,with the introduction of machine and rapid-fire guns and magazine rifles it may be considered as an established fact that a well-defended line cannot be carried by an assault in front until its fire is overpowered or its ammunition exhausted4 ,this conclusion1 which has been drawn from attacks on field-works1 is still more positive in regard to attack upon works of strong profile protected by deep ditches and other obstacles4 ,,dispositions ,,for ,,an ,,assault4 #e4 ,when an assault is ordered the tactical dispositions must be so made as to keep the fire of the defence down to its lowest possible limit1 until the assailant can close in with the bayonet4 ,with this end in view1 batteries are established sweeping the lines2 the assaulting columns1 well supplied with ammunition1 are formed where protected from fire2 working parties are arranged and provided with such tools and appliances as are necessary for removing or overcoming obstacles2 and all preparations are made for simultaneous action by the entire force4 ,it is manifest that to silence the fire of the work the attack must have a marked preponderance of artillery arranged both for enfilade and front fire upon the front of attack and the collateral works2 and that the batteries must be established1 the fire opened1 and the guns of the defence silenced before the assault is made2 and that this fire must continue until the assaulting troops are so near the work as to necessitate its discontinuance to avoid injury to them4 ,the working parties--carrying axes1 saws1 crowbars1 and similar tools which are needed for removing the existing obstacles2 explosives for blowing down gates1 barriers1 etc42 fascines1 gabions1 hurdles1 etc41 for crossing ditches1 covering trous de loup1 and other purposes2 and1 when necessary1 ladders for escalade--move forward with the columns of attack2 the latter must be so handled that1 when the artillery fire is suspended1 they can keep down the fire of the defence with rifle and light machine-gun fire4 ,under cover of this fire the obstacles must be removed by the working parties1 and the first assault made by the troops detailed for this purpose4 ,with these troops should be a certain number of artillerists provided with lanyards1 friction primers1 etc41 to serve any guns that may be captured1 turning them against the defence4 ,a party of engineers provided with high explosives for blowing down gates1 etc41 should follow closely behind the advance in case of an escalade2 they should also be provided with appliances for blowing up magazines1 etc41 when possible1 in case of a repulse4 ,the gates being captured and opened1 the mass of the assaulting troops enter by them and complete the capture of the place4 ,in case of repulse the retreat of the advanced parties is covered1 when possible1 by the infantry fire of the reserves1 and that of the latter by the artillery1 as in the advance4 ,,defence ,,against ,,an ,,assault4 #f4 ,permanent works being designed to be secure against assaults and surprise1 their guns of position are protected as well as circumstances admit against the hostile artillery and infantry fire4 ,during the cannonade preliminary to an assault a wise discretion must be used as to how much ammunition may be profitably expended in replying to it1 and how great an exposure of the men to the artillery fire is justifiable4 ,as a rule but little reply is made from the work4 ,the machine and rapid-fire guns should be withdrawn from the parapets and be protected under bomb-proofs until the relaxation of the hostile fire due to the near approach of the assault allows them to be run out and to open fire4 ,the infantry of the garrison is similarly handled1 being held under cover until the proper moment1 then manning the parapet and pouring a close1 rapid1 and deadly fire upon the assault4 ,the fire of the fronts directly attacked1 both machine-gun and infantry1 will be directed principally at the assaulting columns and working parties1 the collateral works and fronts will1 in addition to pouring a cross-fire upon the assaulting columns1 direct a large part of their machine-gun fire upon the supports and reserves1 while the more powerful guns will generally direct their fire upon the hostile artillery4 ,the troops not needed for manning the parapets are held under cover in a central position as a reserve1 to strengthen the force at any part of the parapet or to meet and drive out any body of the enemy penetrating the work4 ,should the attack be repulsed1 the most rapid and destructive fire from all arms is directed upon the retreating troops with a view to inflicting the greatest possible losses2 but a counter-attack is1 as a rule1 not attempted4 ,when made1 however1 it should be limited to making an advance upon one or both flanks to a position giving a more effective fire upon the retreating troops1 and retiring from this position to the cover of the work as soon as the main attack is completely repulsed and before the advanced troops become compromised by a close engagement with the enemy4 ,,bombardment4 #g4 ,by a bombardment1 technically speaking1 is meant a more or less continuous shell-fire upon a place with a view to destroying magazines1 buildings1 materials1 and supplies of all kinds1 in addition to inflicting the greatest possible losses upon the garrison and producing among the inhabitants a state of terror and unrest1 frequently extending to mutiny1 and finally causing the surrender of the place4 ,the term bombardment is also frequently applied to a cannonade opened upon a place to silence its artillery prior to an assault or during a siege4 ,a bombardment promises success when the place is small and not well provided with bomb-proofs1 when the garrison is weak or of bad morale1 when the inhabitants are numerous and not in sympathy with the garrison1 or when the commandant is weak4 ,a well-built and well-equipped modern fort can hardly be reduced by bombardment with any reasonable expenditure of time and ammunition2 although the successful use of torpedo-shells charged with high explosives will probably render untenable works not designed to resist their effects4 ,when it is designed to reduce a place by bombardment a complete investment is1 as a rule1 necessary only to prevent the withdrawal of the non-combatants 7a severe measure1 but one frequently adopted71 or to insure the capture of the garrison upon the fall of the place4 ,the disposition of the troops is made for the special object in view4 ,the infantry1 cavalry1 and field artillery complete the investment1 if made2 or1 when the place is not invested1 are concentrated at such points as may be necessary to protect the artillery from any sorties from the place1 and to meet and repel attacks from any relieving force4 ,the artillery of larger calibre used for the bombardment proper should consist principally of rifled howitzers and mortars1 which are easier to transport and more suitable for high-angle fire4 ,as it is not intended to dismount or silence the guns of the place by direct or enfilade fire1 an artillery duel should be avoided4 ,the batteries should be located1 so far as possible1 in places screened from the artillery of the defence by undulations of the ground1 etc42 or1 if this is impossible1 by artificial screens as a cover from sight1 and by trenches as a protection from fire4 ,considerable latitude is allowed in selecting sites for batteries4 ,for convenience of supply and unity of command they should be collected in groups1 the batteries of the groups separated by at least #ajj to #bjj yards2 and the groups should be located1 so far as other considerations allow1 near the main lines of communication4 ,if these groups do not entirely surround the place1 they should1 when practicable1 extend at least half way around1 so as to bring a reverse fire on all covers4 ,the fire1 once opened1 should continue night and day4 ,if a conflagration breaks out1 a sharp fire of shells should be directed upon it and its vicinity to prevent its extinction4 ,special efforts should be made to blow up magazines and destroy shops1 storehouses1 docks1 roads1 bridges1 or other communications useful to the defence2 but1 so far as is practicable consistently with these1 an attempt should be made to avoid injury to public monuments1 museums1 antiquities1 and works of art4 ,bombardments are sometimes commenced and continued for a longer or shorter time without the expectation of reducing the place1 but to destroy some of the constructions above mentioned or to prevent the completion or arming of a work which it is intended to attack by other methods4 ,a slow bombardment may also precede the active cannonade which prepares for an assault1 or the systematic artillery attack of a regular siege4 ,,defence ,,against ,,bombardment4 #h4 ,the defence against bombardment is frequently1 from necessity1 strictly passive1 and consists in so disposing the troops and materials as to protect them under bomb- and splinter-proofs1 repairing damages to the latter and to magazines and parapets as occasion offers2 saving the ammunition of the place by firing only such shots as promise to pay for themselves by the effect produced2 and reserving all the strength of the place to meet the subsequent attack1 if made4 ,when circumstances admit1 a more active defence may be made1 by a strong garrison1 by well-conducted sorties which may capture and destroy the hostile guns and batteries and defeat and drive off their supports4 ,sorties of this kind may sometimes be profitably made against the flanks of the attacking force1 or against isolated batteries1 even when a general attack cannot be made4 ,opportunities for their use should not be neglected4 ,,chapter ,,ii4 ,,siege ,,or ,,attack ,,by ,,regular ,,approaches4 ,,preliminary ,,considerations1 ,,definitions1 ,,etc4 #i4 ,by a regular siege is meant a systematic and more or less deliberate attack upon a fortified place1 in which the besieger aims to invest the place and capture its fortifications in succession by regular approaches1 beginning with the most advanced and ending only with the reduction of the innermost keep and the surrender of the garrison4 ,the successive steps of a siege are usually the following3 ,the investment4 ,the artillery attack4 ,the construction of parallels and approaches4 ,breaching by artillery or mines4 ,the final assault4 ,the introduction of modern breech-loading rifled guns1 howitzers and mortars1 rapid-fire and machine guns1 and magazine small arms has brought with it the need of a higher grade of mechanical skill and improved machinery for making the ordinary repairs4 ,this imposes upon both attack and defence the necessity for providing machine shops and tools fitted for work of this kind1 with the steam power required to drive them4 ,in connection with these1 steam sawmills and other simple wood-working machines should be provided1 as well as all other available labor-saving appliances which can be used to lighten the labor of the troops4 ,portable tools1 such as picks1 shovels1 crowbars1 rammers1 axes1 hatchets1 bill-hooks1 gabion-knives1 hammers1 saws1 carpenters'1 joiners' and blacksmiths' tools1 etc41 etc41 must be provided4 #aj4 ,the principal special tools and appliances used are the following1 viz43 sap-forks1 sand-bag forks1 scrapers1 sap-shields1 measuring-rods of various lengths1 pocket compasses with attachments for fastening them to measuring-rods1 tracing-lanterns1 dark and ordinary lanterns1 tracing tape or cord1 tracing pickets or stakes1 fascines1 gabions1 hurdles1 sand-bags1 blindage and gallery frames and sheeting1 etc41 etc4 ,the sap-fork and sand-bag fork 7,pl4 ,i1 ,figs4 #a and #b71 about #d and #d feet long1 respectively1 have steel heads with three and four prongs1 as shown in the figures1 those of the sap-fork being sharp and those of the sand-bag fork blunt4 ,they are used for handling and placing gabions1 fascines1 and sand-bags in position when1 without their use1 the sappers' arms would be exposed to fire4 ,the scraper 7,pl4 ,i1 ,fig4 #c7 is a large hoe1 of about the dimensions given in the figure1 used for levelling off the surface of parapets1 etc4 ,the sap-shield1 introduced by the ,english 7,pl4 ,i1 ,figs4 #d and #f71 is a flat plate of mild steel #c feet #f inches by #a foot #i inches inch1 with two handles on its back as shown4 ,total weight1 about #hj lbs4 ,it may be used as shown in the figure1 and sometimes by small parties as a body-shield in such operations as blowing in gates1 etc41 etc4 ,measuring-rods of rectangular cross-section1 straight and divided into feet and inches1 are needed for special purposes2 but the ordinary rods are cut from round brush wood and to the length required4 ,tracing-tape is usually a white tape1 about #a inches wide1 in lengths of #aej feet1 marked at equal intervals1 usually #e feet1 by short pieces of tape sewed to it4 ,a loop of strong cord is fastened to each end4 ,for convenience in use it is ordinarily rolled into a ball4 ,tracing-pickets are about #ah inches long and one inch in diameter4 ,to make them visible in a dim light the bark is removed from them4 ,ordinary pickets are usually #c or #d feet long1 #a to #a inches in diameter1 sharpened to a triangular point4 ,the tracing-lantern 7,pl4 ,i1 ,fig4 #e7 is a dark lantern with a reflector arranged to throw a light vertically downward4 ,the other tools1 materials1 and appliances above mentioned1 not of the ordinary commercial patterns1 are described in ,field ,fortifications and ,military ,mining1 q4v4 ,,chapter ,,iii4 ,,trenches1 ,,approaches1 ,,parallels1 ,,saps1 ,,splinter ,,proofs1 ,,and ,,passage ,,of ,,the ,,ditch4 #aa4 ,trenches4--,a military trench consists of a ditch and embankment affording cover from direct fire4 ,trenches are used for approaches 7or boyaux71 parallels1 and communications with magazines1 etc4 #ab4 ,parallels are trenches which take their name from the fact that they usually are located on lines approximately parallel to the general front of attack4 ,in a regular siege at least three and frequently a greater number of parallels are used4 ,the exterior one1 which is first made1 is known as the first parallel1 the next one as the second parallel1 and so on4 ,they are used to cover the part of the besieging force known as 8the guard of the trenches10 which protects the men making the approaches1 etc41 and also as 8places of arms0 for assembling troops for assault or for other purposes4 ,the trench of a parallel is usually #aj feet wide at the bottom and #d feet deep1 finished on the reverse with a slope and on the front with two steps and a berm1 with treads of #ah inches and rises of #ae-ah inches 7,pl4 ,i1 ,figs4 #g to #ac74 ,the parapet of the parallel should not be higher than #d feet #f inches4 ,its upper surface1 particularly in the second and third parallels1 should be made approximately plain with a scraper1 and its interior slope should be finished and if necessary revetted1 so as to afford a good infantry-fire4 ,to allow the troops to move out to the front in line1 portions of the interior slope should be cut into steps of not more than about #ah inches rise1 and be revetted with fascines or other materials 7,pl4 ,i1 ,figs4 #ab and #ac74 ,these portions should be #be or more yards long and near the approaches4 ,if a general assault is to be made1 the parallels must be similarly arranged for the necessary length of front4 #ac4 ,approaches are trenches leading up toward the fortification on the front of attack2 they connect the parallels and give protection to the besiegers in moving back and forth4 ,to avoid enfilading fire they usually run in zigzags 7,pl4 ,,viii1 ,figs4 #hj and #ha7 across the capitals of the work1 with branches seldom exceeding #ajj yards in length at the first parallel1 and growing continually shorter as they approach the work4 ,each branch is so directed that its prolongation will pass from #cj to #dj yards outside the most advanced position within effective range held by the defence4 ,at each turning-point of the zigzag the more advanced branch is prolonged from #aj to #bj or more yards to the rear1 to cover the angle of the approach4 ,these returns are also useful for storing trench material1 etc4 ,after the return is completed the sharp angle in the trench is rounded off to allow gun-carriages1 etc41 to make the turn4 ,approaches are usually #d feet deep1 #i to #ab feet wide at bottom1 with slopes in front and rear as steep as the earth will stand1 and have a rough parapet not less than #d feet high1 separated from the trench by a berm of #ah inches1 or more if necessary 7,pl4 ,,viii1 ,fig4 #hb74 ,when drainage requires it1 as it very frequently does1 the bottom of the trench is sloped from front to rear about #f inches2 a ditch cut along the reverse slope1 discharging into the drainage ditches of the vicinity1 or into drainage pits excavated in rear of and outside the approaches4 ,these may be lined with a gabion to prevent their sides falling in4 ,,tracing ,,and ,,constructing ,,parallels ,,and ,,approaches4 #ad4 ,tracing ,parallels4--,parallels are located by engineer officers after careful reconnoissance of the ground4 ,guiding points and lines are marked so as to be readily found in the dusk1 but so that they cannot be seen by the defence4 ,when completely screened from view important points are marked by posting sappers at them4 ,when no other practicable method can be used1 the directions are determined by the use of a pocket compass fastened to a straight measuring-rod4 ,tracing is begun as soon as the approaching darkness will conceal the parties from the defence1 while close objects are still visible4 ,the length of parallel traced by each officer should not exceed that occupied by one unit1 usually a battalion1 as a working party4 7,a battalion of #ejj men will occupy #hjj yards74 ,the tracing party consists of one officer1 one ,n4 ,c4 officer1 and one sapper to each #ej yards of parallel1 with one or two extra men4 ,the officer is provided with a pocket compass and measuring-rod4 ,the ,n4 ,c4 officer has a tracing-lantern and a mallet with muffled head4 ,each sapper carries a roll of tracing-tape1 a tracing-picket1 and a six-foot measuring-rod4 ,the officer stations the first sapper at the initial point1 and1 taking one end of his tracing-tape1 moves along the line of the parallel1 accompanied by the rest of the sappers2 the first sapper places his picket between his feet1 and the ,n4 ,c4 officer drives it into the ground far enough to make it secure4 ,the sapper drops the ball of tape on the ground and lets it run out through his hands until nearly out1 when he checks it1 and when it is all out places the loop over his picket and lies down to await the arrival of the working party4 ,the ,n4 ,c4 officer1 as soon as he has driven the first picket1 follows on to the second1 etc4 ,the officer1 having run out the tape of the first sapper1 halts the second1 takes the end of his tape1 and proceeds as before until the parallel is traced1 and a sapper is left at each #ej yards of its length4 ,each sapper is told the designation1 by number and section1 of the point he occupies4 #ae4 ,tracing ,approaches4--,the approaches are traced in the same manner as the parallels1 but at each turning point of the zigzags a picket is driven1 around which the tape is carried4 ,after tracing the branch in front1 the tape is cut at five yards in rear of the picket1 and the end carried out to the rear in prolongation of the branch in front to indicate 8the return10 which is then prolonged to the proper length 7from #aj to #bj yards7 by a short piece of tracing-tape4 ,,posting ,,the ,,working ,,parties4 #af4 ,the working parties are commanded by their own officers1 under the guidance of the engineers4 ,they carry their arms and ammunition4 ,each battalion 7or other unit7 is marched in column to the depots1 where the tools are laid out in lines1 so that each man can take up his pick and shovel when drawn up in front of them4 ,but when time does not allow of this arrangement1 they are piled1 the picks in one pile1 the shovels in another1 and the men pass the piles in single file to the right of the picks and the left of the shovels1 each man receiving a pick and shovel as he passes the pile4 ,if gabions are to be carried1 they are distributed in a similar way4 ,when two are carried1 the shovel is secured inside one and the pick inside the other1 and the gabions are then carried by the picket inserted for that purpose4 ,when one only is carried1 the pick is usually secured inside it1 the gabion carried on the shoulder1 and the shovel in the hand4 ,the working party1 in column1 provided with its tools1 etc41 is then led by the engineer officer to the parallel1 and forms on right 7or left7 into line along it in single rank at five-foot intervals1 beginning at the initial point of each section4 ,the ,n4 ,c4 officer of engineers assists in this formation1 and each sapper points out to the men of the working party the five-foot intervals marked upon the tracing-tape of his #ej yards1 verifies their positions along it1 and subsequently superintends their work4 ,each man when properly placed drives his pick into the ground at the left of his task1 places his shovel beside it1 and lies down until the command 8,commence work0 is given4 ,when gabions are used the working party is posted in a manner entirely similar1 except that the column is of necessity formed in single rank when marching to the initial point4 ,the men form on right 7or left7 into line and place their gabions in front of the tape and touching each other2 each man then takes out his tools1 places them behind the gabions1 lies down1 and awaits the command to commence work4 ,the sapper sees that the gabions of his #ej yards are properly aligned and touch each other throughout4 ,both the sappers and working parties are divided into reliefs1 usually of eight hours4 ,the sappers of the tracing parties superintend the work of the first relief of the working party1 but are relieved long enough before them 7 hour to #a hour7 for the second relief to become acquainted with the details of its sections before the second relief of the working party arrives4 ,a similar arrangement is made for the third relief4 ,,execution ,,of ,,parallels ,,and ,,approaches4 #ag4 ,simple ,trench4--,a trench made by excavating the earth and forming a parapet without revetment of any kind is known as a 8simple trench10 or as 8simple trench-work40 ,flying sap or flying trench-work4--,when1 in order to obtain cover more quickly1 gabions are used to hold the earth first excavated1 and subsequently to serve as a revetment to the interior slope of the parapet1 the trench is known as a 8flying sap0 or 8flying trench-work40 #ah4 ,construction by ,simple ,trench4--,the first parallel and the distant approaches are usually constructed by the use of the simple trench1 as follows1 viz4 7,pl4 ,i1 ,figs4 #i and #aj73 ,the men having been posted along the tracing-tape at five-foot intervals1 as previously described1 and their positions verified by the engineer officers1 the command 8,commence work0 is given4 ,each man marks the left and front of his task by a line dug with his pick1 and1 commencing at the left of his task1 at once excavates a trench #c feet long1 #a feet deep1 and #f feet wide1 throwing the earth to the front1 and making a parapet #a feet high1 leaving a berm of #a feet4 ,then1 commencing at #a feet from the front of his trench1 he deepens it to #d feet1 making the parapet #c feet high4 ,when the task of a party is finished each man cleans off his pick and shovel1 places them at the rear of the trench1 and leaves them there for the use of the second relief4 ,by excavating in this way1 partial cover while at work and a defensible parapet are rapidly obtained1 and1 at the completion of the task1 the parapet admits of a strong defence1 and affords cover sufficient to allow the first relief to be withdrawn and the second to be posted without exposure4 ,special care must be taken during the work to make the men face toward the parapet while digging1 in order to avoid striking their neighbors with the pick when raising it for a blow4 ,the second relief widens the trench #d feet2 forms a bottom step #ah inches wide with such materials as are available2 heightens the parapet to #d feet1 and throws the rest of the earth to the front to thicken it 7,pl4 ,i1 ,fig4 #h74 ,the third relief widens the trench #b feet at the bottom and slopes off the reverse as steep as the earth will stand4 ,the earth is used to thicken the parapet1 additional shovels and shovellers being provided if found necessary4 ,the approaches 7,pl4 ,,viii1 ,fig4 #hb7 are extended in a similar manner2 the tasks of the reliefs are marked on the sections4 ,variations from these sections are made when rendered necessary by the presence of rock or water in the soil 7,pl4 ,i1 ,fig4 #aa72 when a wider trench is required for a tramway or for free communication2 or1 in special cases1 when a narrower trench will answer the purpose and save work4 ,should a specially heavy fire make additional cover necessary1 it may be obtained by deepening the ditch and thickening the parapet1 leaving its crest at the same height4 ,the sections above given have been found best for ordinary cases4 #ai4 ,construction by ,flying ,sap4--,the construction of the first parallel having indicated to the defence the front of attack1 further operations will usually be subject to a more destructive small-arm and machine-gun fire4 ,this will1 as the siege advances1 render the losses experienced in constructing a simple trench too extravagant1 and a quicker method of obtaining cover must be used4 ,this method is found in the flying sap 7,pl4 ,i1 ,figs4 #h and #ac71 which is executed as follows1 viz43 ,the men are posted and the gabions placed as previously described4 ,the engineer officer having marked the lines1 the order 8,commence work0 is given4 ,each man marks with his pick the front and left of his task 7which in this case is #d #f feet1 leaving a berm of #a feet71 and proceeds at once to dig on its left1 filling first the left gabion1 next the right1 and then throwing the earth over and in front of the gabions4 ,each gabion1 when it is half filled1 is tipped outward until it has a slope of about #d on #a4 ,the filling is then completed4 ,as each man of the first relief occupies only #d feet of front 7#b gabions71 his task is four-fifths as great as it is in executing the simple trench4 ,the second and third reliefs have the same tasks as in the simple trench4 ,when the first relief finishes its task1 every fifth workman 7indicated by the sapper of the section7 retains his pick and shovel and returns them to the depot when he marches past it4 ,the others leave their tools for the use of the second and third reliefs4 ,in good soil the gabions may be filled in from #g to #ae minutes4 ,the ,english sap-shield is designed for use when the fire is so severe that the flying sap with gabions becomes impracticable4 ,owing to its weight 7#hj lbs47 a man can carry but one2 hence a carrying party equal to the working party assists in placing the shields and then retires4 ,this gives to each workman a task of #c #f feet4 ,the shields are placed as shown in ,pl4 ,i1 ,fig4 #f2 the trench is executed as previously described1 the earth being thrown over and beyond the shield4 ,the shields are removed after the task of the first relief is finished4 ,the sap-shield is designed to be used in special cases for covering the head of a full sap 7described further on71 in which case it is placed as shown on ,pl4 ,i1 ,fig4 #d2 and also as a body cover for a man moving for a short distance in the face of a heavy fire1 as is necessary at times in sapping and mining operations4 ,it has not yet stood the test of service in a siege4 ,,splinter-,,proof ,,cover4 #bj4 ,splinter-proofs for the guards of the trenches1 for field-hospitals1 latrines1 etc41 should be provided as soon as possible after the parallels are finished4 ,they may be placed in the returns of the approaches1 or in rear of the parallels1 and be connected with them by trenches4 ,pl4 ,,ii1 ,figs4 #ad-af1 show their construction when in rear of the parallel and revetted with logs1 fascines1 or sawn lumber4 ,the trench is #i feet wide by #d feet deep4 ,its front edge should be #be or #cj feet in rear of the reverse slope of the parallel4 ,this width of trench will allow #b to #d men per yard of its length to work advantageously4 ,they should finish it in #h hours4 ,in digging the trench the earth is thrown out on both sides1 leaving a berm of about #a feet on each side to allow the woodwork to be properly placed4 ,when this is completed the earth in rear is thrown forward to complete the cover1 as shown in the plate4 ,steps for egress and openings for light and ventilation may be placed at intervals along the rear1 and1 when desirable1 bunks may be built1 as shown in the figures4 ,when the splinter-proofs are built in the returns of the approaches1 the overhead cover may extend entirely across1 steps and openings being provided as in the previous case2 or posts and longitudinal beams may be set in the trench to hold up the rear end of the cross-beams1 leaving the rear of the splinter-proof open4 ,portions of this may be closed1 if desired1 by leaning short posts or fascines against the longitudinal beam and banking earth against them4 ,the splinter-proofs may generally be drained into the parallels or approaches4 ,when this cannot be done drainage-pits must be used4 ,limited portions of the splinter-proofs may be protected against leakage through the earth cover by first filling over the covering beams with earth1 packing it to a smooth surface with a gentle slope1 placing upon it raw hides1 roofing felt or other waterproof material1 and then completing the cover by adding the necessary thickness of earth1 giving finally to its top surface a slope to carry off the rain4 ,,bomb-,,proofs4 #ba4 ,when1 in the close attack of the work1 the besiegers are subject to vertical fire from small mortars1 better overhead cover must be obtained by bomb-proofs1 constructed by deepening the trench1 using stronger beams1 and a greater thickness of earth4 ,twelve-inch timbers laid touching each other1 with spans of #e feet and #e feet of earth cover1 have been considered sufficient2 but with the improvement of high-angle fire and the use of high-explosive shells greater protection will be needed in the future4 ,experimental data for fixing the amount is not now available2 an approximate thickness of earth cover may be computed as indicated below4 ,the mining effect of dynamite in common earth is something less than twice that of an equal weight of gunpowder4 7,see ,military ,mining1 ,arts4 #ac and #ad47 ,an explosive enclosed in a strong case1 however1 expends a part of the energy due to explosion in rupturing this case4 ,the stronger the explosive the less will be the percentage of the total energy required for breaking the case1 and the greater the percentage remaining for performing other work4 ,for this reason equal weights of high explosives and of gunpowder enclosed in strong shells will not produce the same relative effects in forming craters1 c41 that they would if contained in paper cases4 ,the effect of the high explosive is relatively much greater when contained in a strong shell4 ,experiments made at ,fort ,hamilton1 #ahij-ia1 with #h-;inch shells loaded with explosive gelatine1 showed this explosive to have between #d and #e times the effect of gunpowder1 while in paper cases the relative effects were as #a4g to #a4j4 7,see ,report of ,board of ,ordnance and ,fortification1 ,ex4 ,doc4 ,no4 #ab1 #eb;d ,congress1 #ast ,session1 ,january #eth1 #ahib47 ,since the mining effects of the charges contained in shells are1 however1 less than when packed in thin cases1 the thickness of cover determined by the use of the usual mining formulas should err on the side of safety4 ,knowing the charge contained in shells to be fired against a bomb-proof1 and their probable penetration1 the formulas given in ,arts4 #g to #ab1 ,military ,mining1 may be used for finding equivalent common mines and radii of rupture for dynamite and explosive gelatine by substituting in them #a_/ag for #a_/aj4 ,the values given in ,art4 #aa will probably be sufficiently accurate for the radii of rupture4 ,the cover given in the direction of the fire must be greater than the sum of the penetration and the radius of rupture4 ,when the penetration is equal to or greater than twice the ,l4 ,l4 ,r4 of an equivalent common mine a camouflet will probably be formed1 whose radius of rupture1 from the formulas1 will be equal in all directions and may be assumed as of the ,l4 ,l4 ,r4 of the equivalent common mine4 ,in this connection1 see par4 #fa1 p4 #eh4 ,,sapping4 #bb4 ,when the trenches have been carried so near the work that the simple or flying trench cannot be used without undue loss1 recourse must be had to the sap4 ,a sap is a narrow trench 7subsequently widened71 which is continually prolonged in the desired direction by digging away the earth at its head and throwing it to the front and exposed flank as a cover for the working party4 ,when the sap is subject to an oblique front-fire1 exposing one flank only1 the parapet is constructed on that flank and at the head4 ,this is known as a single or full sap4 ,when both flanks and the head of the sap are exposed to fire two full saps are driven parallel and very near to each other1 each with its parapet on the outer flank4 ,the tongue of earth left between them is removed to widen the narrow trenches1 thus making a single trench with a parapet on each side4 ,this is called a 8double sap40 ,the trench is sometimes deepened and given a splinter-proof roof or cover4 ,this is known as a 8blinded sap40 ,a sap gaining ground to the right and front is called a 8right-handed sap20 its parapet is on its left flank4 ,a 8left-handed sap0 has its parapet on its right flank4 ,to expedite the work in sapping several reliefs should be employed1 and task-work should be adopted to induce the men to work rapidly4 ,in all sapping operations the use of the simple trench and flying sap will be resumed when circumstances admit without involving too great losses4 #bc4 ,the full sap 7,pl4 ,,ii1 ,figs4 #ag-ba7 requires a detachment1 or 8brigade10 of #a non-commissioned officer and #h men1 provided with the following tools1 viz43 ,for ,no4 #a1 a miner's pick1 a miner's shovel1 a measuring-rod1 #d' #f1 marked at #c'1 and a sand-bag fork4 ,no4 #b1 a measuring-rod of #a' #f and a shovel4 ,no4 #c1 a pick1 a shovel1 and a measuring-rod #e' long1 marked at #d' #f4 ,no4 #d1 a shovel and a scraper with a handle #i' long4 ,for the rest of the detachment1 a #f' measuring-rod1 knee-caps for #d men1 #b shovels and #a pick 7in reserve71 and1 when necessary1 a crowbar1 axe1 and bill-hook4 ,from #ajj to #aej sand-bags are supplied to each detachment4 #bd4 ,organization and ,duties of the ,detachment4--,the sappers are numbered #a1 #b1 #c1 and #d in each rank2 the front rank extends the sap #a yard and is then relieved by the rear rank1 and so alternately4 ,the sappers change places at each relief2 those who serve as ,nos4 #a and #b during their first task becoming ,nos4 #c and #d during the second1 and so on throughout their tour4 ,if a detachment is reduced below #h in number by casualties it nevertheless keeps #d men at work driving the sap1 and reduces its reserve until new men are supplied4 #be4 ,driving the ,sap4--,the sap is driven as follows1 viz43 ,nos4 #a and #b dig a ditch #d' #f deep1 #a' #f wide at bottom1 and #c' or more at top2 the berm side has a slope of #c_/a1 and the reverse is vertical1 or as nearly so as the earth will stand4 ,they leave no berm1 as they need all the cover they can get4 ,nos4 #c and #d widen this trench #b feet and form a berm of #a' #f by digging away the foot of the parapet and throwing the earth upon its top and exterior slope4 ,the head of their work is kept at #i' in rear of the head of the sap4 ,the side parapet made by ,nos4 #a and #b is about #b' #f high and bullet-proof 7about #b' #f to #c' thick7 at #ah inches above the ground4 ,the head parapet is made up of about #fj sand-bags1 from to #b filled4 ,it joins the side parapet and extends across the head of the sap4 ,it is about #b' #f high4 ,as the sap is driven forward the head parapet is advanced by throwing the rear sand-bags over to the front by hand or by the use of the sand-bag fork4 ,in excavating the trench ,no4 #a kneels down1 undermines1 and digs down enough earth to advance his trench about #i inches4 ,he is replaced by ,no4 #b1 who shovels this earth upon the side parapet toward the head of the sap4 ,no4 #a then resumes his place and throws the sand-bags at the head of the trench over the parapet until he has uncovered about a foot in advance4 ,he uses a sand-bag fork when necessary4 ,the trench is advanced #i inches more in the same manner4 ,no4 #b1 besides throwing out the earth dug by ,no4 #a1 trims up the slopes and gives the trench its proper width and depth4 ,nos4 #a and #b change places when they have advanced the head of the sap #a' #f1 and are relieved as before stated when #c feet is gained4 ,nos4 #c and #d work together upon their task4 ,in shovelling the earth upon the parapet they throw it somewhat toward the front and regulate its height with the scraper4 ,the rate of advance is usually from #b to #d feet per hour4 ,widening the ,sap4--,the sap is widened by working parties1 usually of infantry1 who work at about1 but not less than1 #be feet in rear of the head of the sap4 ,in an approach their task is equal in volume to that of the sappers1 and can be finished in one relief4 ,in a parallel when steps are to be provided1 a second relief makes the steps1 drainage ditches1 drainage pits1 etc4 ,a change of direction in a full sap 7,pl4 ,,ii1 ,fig4 #bj7 is made by ,no4 #a turning in the new direction and working through the old side parapet2 ,no #b throwing the earth over the old head parapet4 ,the sand-bags of the old are gradually removed and used for a new head parapet1 #bj or #cj additional sand-bags being ready for use if needed before the others can be safely removed4 ,nos4 #c and #d follow on as before4 ,a return can be driven back when desired by another detachment of sappers4 ,no head parapet will be needed1 but the side parapet will be kept a little in advance of the head of the sap4 #bf4 ,breaking ,out a ,sap from a ,parallel4--,the head parapet of a sap is about #b' #f high4 ,the parapet of a parallel is about #d' #f high4 ,a sap of the usual form driven through the parapet of a parallel will expose the latter to fire through the opening formed4 ,to reduce the danger from this exposure1 the sap is broken out at night1 and to cover the opening in the shortest time two or three men may creep over the parapet of the parallel and cover themselves by rapidly digging a hole1 from which they may work back and join the sappers1 who are working outward4 ,the sap being driven obliquely to the front1 the trench widened1 and the parapet made full size 7,pl4 ,,ii1 ,fig4 #ba71 the opening will be covered2 or a few men may in some cases construct in front of the parallel a short section of flying sap1 under cover of which the full sap may be broken out 7,pl4 ,,iii1 ,fig4 #bh74 ,preliminary preparations for breaking out should be made during the day1 but should be so conducted as not to indicate the selected point to the enemy4 #bg4 ,circular places of arms 7,pl4 ,,ix1 ,fig4 #hc7 may be formed in front of a parallel by breaking out two single saps from points #hj to #ajj yards apart and so directing them as to meet at #be or #cj yards in front of the parallel4 ,they may be used by the guards of the trenches or as depots for trench material1 etc4 #bh4 ,shallow ,sap4--,when the presence of water in the soil or of rock near the surface prevents driving the full sap #d' #f deep1 a shallow or modified sap 7,pl4 ,,ii1 ,figs4 #bb and #bc7 may be used1 provided a trench #c' deep can be driven forward4 ,in this case ,nos4 #a and #b must both work kneeling1 and ,nos4 #c and #d must throw the earth well to the front and keep the parapet as high as possible1 leaving the construction of the berm to the widening party1 who will give to the trench the necessary width1 and will then obtain earth for strengthening the parapet by deepening the trench when practicable and widening it when necessary1 making1 however1 no irregularities which will injure it as a communication and no depressions which will collect water4 ,this sap advances about as rapidly as the full sap4 #bi4 ,overground ,approaches4--,when the water or rock comes to the surface of the ground1 approaches can1 under favorable circumstances1 be driven for short distances by carrying forward earth in sand-bags1 forming with them head and side parapets1 and moving forward by continually building up the latter and advancing the former as before described4 ,the expenditure of time1 labor1 and sand-bags is so great in driving approaches in this way that the minimum height of parapet 7possibly #e'7 should be made with sand-bags4 ,this may be subsequently heightened and strengthened with earth brought forward in barrows or hand-carts and thrown upon the top and exterior slope4 #cj4 ,double ,sap4--7,pl4 ,,iii1 ,figs4 #bd1 #be1 and #bf74--,the double sap consists of two parallel single saps driven side by side1 the cutting lines of the berms1 usually #aj feet apart1 making the bottom of the completed trench #g feet wide4 ,it is used when the zigzags1 to avoid enfilade1 make such a slow advance as to be no longer profitable1 i4e41 when the amount gained in advance does not exceed the length driven4 ,the double sap is directed toward the work1 and is exposed to an enfilading and also to a slant fire from both directions4 ,it must therefore have a parapet in front and on both flanks4 #ca4 ,execution of the ,double ,sap4--,the double sap is driven by two detachments1 each organized and equipped exactly as for a single sap1 except that a greater number of sand-bags should be supplied when practicable4 ,the sappers work as in driving a single sap1 with the following modifications only3 ,the ,nos4 #a prolong their head parapets until they meet1 and in advancing their heads of sap leave undisturbed the #d feet of head parapet intervening between their trenches1 but1 by continually throwing sand-bags or earth obliquely to the front1 keep the head parapet continuous and nearly straight4 ,this leaves between the trenches made by the ,nos4 #a and #b of the two detachments a tongue of earth #d feet thick1 surmounted with a parapet about #b' or #b' #f high1 which serves as a parados and protects these sappers from reverse fire4 ,nos4 #c and #d of both detachments1 in completing their tasks1 remove this tongue and pass forward the sand-bags forming its parapet for use by ,nos4 #a and #b2 otherwise the tasks are as in driving a single sap4 ,when sufficient sand-bags are not available the middle part of the head parapet must be made of loose earth1 giving much less protection to ,nos4 #a and #b4 ,this sap1 from its method of construction1 is completed by the sappers without the assistance of the infantry working parties4 ,its rate of advance is about the same as that of the single sap4 #cb4 ,changing ,direction of a ,double ,sap4--,when a change of direction is to be made ,no4 #a of the first detachment marks on the berm the width of the top of the trench 7#aj'71 ,nos4 #a and #b of the wheeling flank come around the tongue and the leading sappers of the two detachments start their sap-heads in the new direction4 ,nos4 #c and #d of both detachments remove the tongue of earth and complete the parapets of the original trench and then follow up their ,nos4 #a and #b as before4 #cc4 ,breaking ,out a ,double ,sap from a ,parallel4--,a double sap is broken out by methods entirely similar to those already described for the single sap 7,pl4 ,,iii1 ,figs4 #bg and #bh74 ,the figures explain themselves4 #cd4 ,traversed ,sap4--,a sap may be traversed to protect it against enfilade by frequent changes of direction1 generally rectangular 7,pl4 ,,iii1 ,figs4 #bi1 #cj1 and #ca71 or by making hollow traverses by blinding the sap at points separated by limited distances 7,pl4 ,,iii1 ,figs4 #cb-ce74 ,in traversing a double sap by change of direction1 a single sap is broken out to the right or left 7or one in each direction7 and pushed forward to the desired length4 ,from the flank of this the double sap is again broken out and driven to the front until another traverse is required4 ,when the saps are driven to both right and left a double sap is driven to the front from the extremity of each1 and at the next change of direction the single saps are driven towards each other until they meet1 and the double sap is driven in the prolongation of its original direction4 ,this forms what is called a cube traverse1 and gives additional room in the communications4 ,the single sap is used in making traverses1 since by throwing all the earth on one side better cover is given4 ,when the sap is so far advanced that it becomes subject to a reverse fire the double sap will have to be used in making the traverses4 ,length of ,traverses4--,traverses should extend at least #ab feet beyond the trench in their rear1 which will give them a length of from #be to #cj feet on the berm4 ,the salient angles of the sides of the trenches should be rounded as much as practicable to allow the easy passage of guns1 and those of the parapets should1 when necessary to screen the trench1 be held as nearly vertical as practicable by sand-bags4 ,ramps leading to the surface of the ground may be made in rear of the traverses when needed4 ,for guns they are #h' wide1 with slope not greater than #a_/d4 ,the work in making traverses being considerable1 they should be spaced as far apart as practicable4 ,spacing ,traverses4--,in driving the sap to the front the low head parapet of the sap will defilade a less length in the rear than would the finished parapet of the traverse1 which is from #b to #c feet higher4 ,the sap is1 nevertheless1 pushed forward to as great a length as will be defiladed by the traverse when finished1 the sappers meanwhile passing the partly protected portion by stooping or creeping when necessary4 #ce4 ,traverse by ,blinded ,sap4--,in traversing a sap by blinding a part of its length 7,pl4 ,,iii1 ,figs4 #cb-ce7 the sap is first deepened #b feet over this part2 mine-cases1 frames similar to mining-frames1 or regular blindage-frames 7see ,military ,mining1 ,arts4 #ec-ee7 are then put in position1 the side slopes are held up by sheeting1 when necessary1 and the top is covered with sheeting1 fascines1 rails1 or other material2 earth is then thrown upon the top to bring it up to the desired height for a traverse1 which will usually give at least #c feet of earth covering4 ,when a considerable thickness of earth is to be used the frames must be made correspondingly strong4 ,for a clear opening1 #f feet at bottom1 #h feet at top1 and #f' #f high the ,english engineers recommend frames at #c-;foot intervals1 with #f-;inch square posts1 #b-;inch thick sills1 and #i inch #f inch caps #ab feet long4 ,the end frames should be braced against outward thrust by #f #f struts4 ,these traverses are usually made at least #bj feet in length4 ,they can be used only when good drainage can be secured4 #cf4 ,crowning the ,covered ,way 7,pl4 ,,iv41 ,fig4 #cf74--,the traversed sap is used for 8crowning the covered way10 which consists in constructing a battery or infantry parapet along the crest of the covered way1 from which a fire can be brought upon the ditch and the scarp-wall of the work4 ,to accomplish this the sap is run parallel to the crest1 with its nearer cutting line #ah or #bj feet from it4 ,for an infantry trench the traverses may be of the dimensions already given4 ,to cover a battery they should be about #cc' long4 ,it will generally be necessary to use the double sap altogether in their construction1 but usually the earth excavated by ,nos4 #c and #d of both brigades will be thrown on the parapet next the work1 the parapet on the reverse side formed by ,nos4 #a and #b affording sufficient cover for constructing the sap and traverses4 ,the parapet is prepared for infantry fire as described for the parallels4 ,the emplacements for guns1 the service magazines1 etc41 etc41 are prepared and the embrasures are cut1 or the parapet prepared for the overbank carriages at the last moment1 under cover of the small-arm and machine-gun fire from the parallels and places of arms1 and the artillery fire from batteries1 which do not endanger the working parties4 #cg4 ,trench ,cavalier4--,in order to obtain a greater plunge upon the covered way and ditch1 short lengths of double sap are sometimes run at right angles to the direction of the crests of the covered way at about #cj yards outside its salient4 ,the parapet on the side of the sap towards the work is thrown forward and built up to the desired height with gabions and sand-bags1 and provided with steps and sand-bag loopholes1 giving a short length of parapet with considerable command1 firing directly along the covered way at short range4 ,this construction is called a ,trench cavalier4 ,it will be seldom1 if ever1 used in the future4 #ch4 ,former ,methods of ,sapping4--,before the general introduction of machine and rapid-fire guns and of small arms of extreme accuracy and penetration saps were constructed by ,no4 #a sapper driving a trench #ah #ah1 which was enlarged successively by ,nos4 #b1 #c1 and #d4 ,cover for the sappers was obtained by the use of a sap-roller 7a large gabion1 #g' #f long and #d' in diameter1 stuffed with fascines and rods7 as a movable head parapet1 and the construction of the side parapet was expedited by the use of gabions1 sap-fagots1 etc4 ,this method cannot be used against an enemy well equipped with modern weapons4 ,it is referred to only as a suggestion that a readily improvised modification of it might be used to capture1 with the least possible loss1 a party of rioters1 criminals1 or other badly-armed men occupying an isolated house or other cover4 ,,passage ,,of ,,the ,,ditch4 #ci4 ,when breaches which are practicable are made in both counter-scarp and scarp of a dry ditch an assault may sometimes be made successfully2 but when the scarp-wall is not breached1 or when1 for other reasons1 an assault from the crowning of the covered way is not considered advisable1 the ditch must be crossed and the breach1 when made1 must be crowned by regular approaches4 ,this is accomplished by the use of a sap1 single or double1 depending upon whether it is exposed to fire upon one or both flanks4 ,owing to the plunging fire of the defence it may be necessary to make the sap deeper than #d' #f1 or in some cases to blind it for a part or the whole of its length4 ,it is generally impracticable to drive the sap down the slope of a breach in the counter-scarp2 therefore a blinded descent 7,military ,mining1 pars4 #ec and #ed7 is used4 ,it is so directed that when the counter-scarp is reached the floor of the gallery will be at the required depth below the bottom of the ditch2 i4e41 at the depth fixed for the bottom of the sap4 ,when the small-arm fire of the defence is so severe as to necessitate blinding the sap from the counter-scarp across the ditch1 it will usually be imperative to provide a shield1 under cover of which the sappers may start the blinded sap4 ,this may be made of boards covered with bullet-proof iron-plates1 and of such width and length that it may be carried through the gallery1 thrust out into the ditch1 and then turned1 placed in position1 and blocked up at such angle and to such height as may be wished1 by men who move on their hands and knees and support the shield on their backs4 ,under cover of this shield the head parapet of the blinded sap may be thrown up and the sap then driven in the usual way4 ,for method of breaching by mines1 see ,military ,mining1 pars4 #ia and #ib4 ,after breaching the scarp1 if an assault is to be made1 the counter-scarp1 for a length equal to or greater than the length of the breach1 should be blown down1 to give the assaulting party access to the breach4 ,if the breach is to be crowned1 and approaches are to be driven against interior retrenchments1 a gallery of descent should be driven to the counter-scarp at one side of the breach before the assault is made4 ,from this a trench should be driven to the crowning of the breach 7usually by flying sap71 by means of which communication is maintained between the crowning of the breach and the exterior4 #dj4 ,a wet ditch without current may be crossed by building a causeway1 upon one or each side of which a parapet is constructed 7,pl4 ,,iv41 ,figs4 #cg1 #ch1 and #da74 ,the floor of the gallery of descent should strike the ditch at about one foot above the level of the water4 ,the counter-scarp wall having been broken through1 a shield similar to that described in the preceding paragraph may be used to cover the sappers working at the outlet of the gallery in the first stages of the succeeding work4 ,the causeway is built by throwing into the ditch short fascines or brushwood mats1 having bound up with them stones enough to sink them1 broken-stone gravel or other available material1 until the causeway is #h or #aj feet long1 about one foot above the level of the water and wide enough for the roadway and parapets4 ,the head and side parapets are then constructed with sand-bags1 which are passed out under the shield and piled at its head and sides4 ,the causeway is continued by throwing material over the head parapet1 and the approach is driven forward somewhat like a sap4 ,so soon as the head and side parapets are made the shield may be raised up and supported upon two or three cross-balks resting upon the side parapets4 ,it may then be progressively moved forward and the approach in its rear be blinded by sappers working under its protection4 ,unless the plunge of the fire upon the approach is equal to or greater than #de this shield will1 however1 when vertical1 cover a greater length of trench than when in a horizontal position4 ,it may1 therefore1 if desired1 be turned into a vertical position and be supported by a frame built for that purpose1 which can be moved forward as the approach advances 7,pl4 ,,iv41 ,fig4 #da74 ,when the head of the approach is subjected to the fire of rifle-bullets only1 it may be practicable to dispense with the head parapet1 replacing it with a bullet-proof screen covering the head of the approach and with wings extending back and overlapping the side parapets 7,pl4 ,,iv41 ,fig4 #dj72 the shield floating on a raft of light logs1 or other material which cannot be sunk by rifle fire4 ,this shield would1 of course1 be erected and launched under cover of the one already referred to4 ,to save sand-bags1 etc41 the interior slope of the side parapets may be revetted with gabions about #d' #f long1 resting on two short fascines and crowned with three others1 giving a height of about #f' #c4 ,upon these1 when necessary1 cross-beams are laid and the blinding of the approach is finished with sand-bags thrown on top4 #da4 ,a wet ditch with current1 or one in which the water level may be varied by the defence1 presents greater difficulties4 ,the method of crossing which seems most promising is by a causeway made of materials which will allow the water to pass freely through it4 ,for this purpose it is usually recommended to use casks with their heads knocked out1 or strong gabions lashed to balks1 so as to form continuous tubes1 which are loaded with stones and sunk with their axes parallel to the counter-scarp by sappers working under cover of a shield4 ,when the top of the causeway is about a foot above the high-water mark it is levelled off with fascines and the approach driven forward as previously described4 ,when available1 iron or terra-cotta pipes of large diameter may1 perhaps1 be advantageously substituted for casks or gabions4 ,cormontaigne1 at ,philipsburg1 in #agcd1 successfully used floating bridges of fascines with parapets of gabions and fascines covered with raw hides4 ,two bridges were made4 ,they were #abh feet long1 #dh feet wide1 and #f feet thick4 ,the water was about #ae feet deep4 ,to construct and hold in place1 in a strong or varying current1 a floating bridge of sufficient width and depth to support1 without sinking or capsizing1 the parapets necessary for protection against modern small arms and machine guns is a task presenting such great difficulties that it will hardly be undertaken1 except as a last resort1 and then with a very uncertain issue4 ,when1 however1 the fire of the work is nearly or entirely silenced1 a floating bridge of pontoons1 casks1 spars1 or other materials1 with a slightly masked roadway1 may furnish a sufficiently good crossing and may be constructed with little difficulty and loss4#a ,,chapter ,,iv4 ,,batteries1 ,,observatories1 ,,and ,,magazines4 #db4 ,batteries in siege operations are for field-guns1 siege-guns1 howitzers1 and mortars4 ,when the gun-platform is on or above the level of the ground they are known as 8elevated batteries10 when it is below the surface as 8sunken batteries40 ,when they are concealed from the view of the enemy by natural or artificial screens they are called 8screened0 or 8masked batteries10 and when on sites which can be seen by the enemy 8exposed batteries40 ,,general ,,requirements ,,of ,,siege ,,batteries4 #dc4 #ast4 ,a good platform for and sufficient space to work each gun4 ,the platform must be suited to the gun used4 ,the space required is about #ae feet front by #bj to #be feet depth4 #b;d4 ,a parapet which cannot be penetrated by the projectiles which will be fired against it1 and which is high enough to afford cover to the gun and its detachment against curved fire4 ,a thickness of #cj feet of earth will usually be enough for the most exposed batteries4 ,a less thickness may be used when the conditions justify it4 ,the height of the interior crest above the terre-plein should not be less than #g feet when this is attainable and may sometimes be greater4 #c;d4 ,traverses4 ,each gun is usually separated from the next by a traverse1 whose thickness when subject to enfilade fire is the same as that of the parapet 7#cj feet72 under other circumstances the thickness may be reduced if deemed advisable1 but should1 when practicable1 be such that a shell bursting at any point within it will blow out at the top or on one side only4 #dth4 ,bomb and splinter proofs sufficient to cover the gun detachment and reserves against vertical fire4 ,the thickness of cover for these is to be regulated according to the principles laid down in par4 #ba4 #eth4 ,magazines which will hold at least #bd hours' supply of ammunition1 besides recesses near the guns for shells and a few cartridges4 #fth4 ,easy and direct communications for bringing up the guns and placing them in position2 including tramways1 ramps1 etc41 etc4 #gth4 ,look-outs or observatories from which the effect of the fire can be seen4 ,these when possible will be placed in high sheltered places well on the flanks of the battery and preferably in advance of it4 ,they may be connected with it by signals1 telegraph1 or telephone1 when necessary4 #hth4 ,screens4--,earthen screens should when possible be thrown up in front of all exposed batteries4 ,,construction ,,of ,,batteries4 #dd4 ,batteries for ,field ,guns4--,when the place is invested1 the field artillery is placed in positions considered most advantageous for repelling attacks from the garrison upon the investing force4 ,gun-pits 7described in 8,field ,fortifications07 are usually made at once for cover for the guns and their detachments4 ,when any of these sites are occupied during the siege the gun-pits may be connected and converted into a battery as indicated by ,pl4 ,,iv1 ,figs4 #db-de4 ,a similar construction may sometimes be used during the siege when the artillery fire of the place is weakened1 and it is desirable to place a field battery in position for reaching some point in the work4 ,as a rule1 however1 batteries for field guns will during the siege be constructed in the same way as are those for siege guns and howitzers4 #de4 ,batteries for ,siege ,guns and ,howitzers4--,these may be screened or exposed1 sunken1 or elevated4 ,as a rule each battery has a magazine on each flank4 ,the amount of powder necessary to serve two guns for #bd hours 7#aej to #bjj rounds per gun #bejj to #fjjj lbs47 is as much as it is advisable to have in one magazine1 in order to limit so far as possible the disastrous effects of an explosion4 ,for this reason the number of guns in a battery is usually restricted to four4 ,this number may be increased when necessary1 or when howitzers firing small charges render it unobjectionable4 ,elevated batteries require much more labor for their construction and for obtaining cover for the men and material than the sunken batteries4 ,they are therefore used only when the target has to be seen and the gun has to be raised for this purpose1 or when owing to the presence of rock or water in the soil1 or the liability of the site to be flooded it is impracticable to sink the platforms below the surface4 ,as a rule they can be constructed only when covered by a screen either natural or artificial1 and then with earth carried in wheelbarrows1 sand-bags1 etc41 etc4 ,sunken ,batteries4--,when constructed under cover of a screen the depth of the terre-plein of a sunken battery may be limited by the presence of rock or water in the soil1 the character of the guns and carriages1 and the time available for the work4 ,in a hasty construction the depth of the terre-plein is usually limited to from #c to #d feet1 which can be dug out in a short time4 ,when more time is available the gun platforms may be put at #e to #f feet below the surface and the other parts of the terre-plein may be sunk still lower4 ,this gives but little height of parapet1 and the extra earth may be used for giving additional thickness of cover to the splinter-proofs under the traverses and flanks1 and also to the magazines4 ,a great variety of plans and profiles may be adopted for batteries of this class1 the details of which need not be given1 since they will be modifications of those described in ,field ,fortifications and ,permanent ,fortifications1 and of the exposed battery to be next described4 ,as they are built under cover of screens and are not subject to fire during construction1 work upon them may be continuous and by day as well as by night4 #df4 ,screens4--,the natural screens used for cover are elevations1 woods1 hedges1 existing buildings1 walls1 etc41 etc4 ,artificial screens may be made by setting out bushes to imitate hedges or adopting similar devices1 which1 however1 will usually fail to deceive an active enemy4 ,a trench with the earth thrown to the front1 forming a glacis-shaped parapet1 will1 however1 generally be effective4 ,it must be made of such length that the enemy cannot know the exact position of the battery1 and of such height and thickness that he cannot afford to expend enough ammunition to breach it4 ,this affords not only concealment during construction1 but also a remarkably efficient cover to the battery against hostile fire4 ,screens1 natural or artificial1 should be from #ej to #ajj yards in front of the batteries1 so that the enemy's aim may not be corrected by seeing the points struck by his shells4 ,unless the screen is of material which will break up into injurious splinters under hostile fire1 only enough should be removed before opening fire to unmask the target of each gun1 leaving the remainder for concealing the points struck by shells1 even if it affords no cover against their penetration4 #dg4 ,exposed ,sunken ,battery4--,before describing the construction of this battery it is necessary to state that upon a site fully exposed to the accurate concentrated fire of a work1 directed at night by light balls or electric lights1 it will in general be practicable to construct batteries only by sapping1 and even then with considerable losses4 ,but these conditions seldom exist1 since in the distant attack it is usually possible to construct and arm the battery before it is discovered by the defence1 and in the close attack the fire of the defence is generally so much reduced that some exposure is justifiable4 ,while the battery to be described is classed as an 8exposed battery10 it is understood that it may also be constructed under cover of a parallel or other trench1 and that in all cases when practicable a natural or artificial mask is used to conceal the first night's work from the enemy4 ,it is assumed from the results obtained in practice that1 with the material conveniently stored1 the battery can be traced1 a central trench and splinter-proof covers be made during the first night1 and the battery finished and armed during the second4 ,the general design and details of this battery are due to the ,royal 7,british7 ,engineers4 #dh4 ,tracing the ,battery4--,the battery is traced under the direction of an engineer officer by one or two tracing parties1 each composed as follows3 #a non-commissioned officer with a #f-;foot measuring-rod and tracing-lantern1 and #d sappers1 one carrying a measuring-tape and bundles of pickets1 one a field-level1 one several tracing-tapes1 and one a mallet or hand-axe2 about #ge pickets and #abjj feet of tracing-tape should be provided4 ,the line of fire of the first gun of the battery 7xy1 ,pl4 ,v1 ,fig4 #df7 is accurately laid out and marked by daylight4 ,at dusk one party drives a picket at ,i1 where the directrix crosses the projection of the base of the interior slope1 and from this as an origin lays out the cutting lines of the central trench1 ,i1 ,,ii1 ,,iii1 ,,iv1 ,v1 ,i1 making the trench #e feet wide and of the length required for the number of guns 7 ,no4 of guns #de'--aj'72 commencing then at a point ,a1 #g' #f to the left of ,i and in the rear cutting line1 this party lays out the line a1 b1 c1 d1 e1 etc41 444 m1 n1 o1 as indicated1 the direction n1 o1 leading to the parallel4 ,the second party1 beginning at ,a1 lays out ,a1 ,b1 ,c1 communicating with the parallel1 and then the inner cutting line of the ditch ,d1 ,e1 ,f1 ,g1 ,h1 ,i1 allowing for a thickness of parapet of #cj feet and an ultimate width of ditch of #ab feet 7,d1 ,e1 and ,h1 ,i74 ,two parties should trace the battery in #be minutes1 one party in #de minutes4 #di4 ,constructing the ,central ,passage and ,splinter ,proofs4--,the first relief of working party for the central passage is posted and commences work at once 7,pl4 ,v1 ,figs4 #dg-dh74 ,each man's task is #e feet in length and #d feet in depth 7giving #ajj cubic feet74 ,it may be completed in #d hours1 and should be in #f at most4 ,the second relief 7,pl4 ,v1 ,figs4 #di-eb7 excavates the cartridge recesses1 trims up the work done by the first relief1 lowers any earth that stands too high1 revets the slopes of the gun portions1 puts in frames and sheeting when needed in the splinter-proofs1 places the bearing planks and balks of the latter1 which should be at least #i inches thick and #i feet long1 except over the cartridge recesses1 where they are #ab feet1 and when possible deepens the central passage under the splinter-proofs to #e' #f for a width of #b feet to form a seat for the men4 ,it also places one or two planks along the passage to serve as a bench for shells4 ,the latter part of this work can be done by daylight4 ,the parapet formed by this excavation is about #b feet high4 ,this is so masked or so inconspicuous as not to draw upon itself the artillery fire of the defence4 ,the construction of the battery will be continued usually on the following night4 #ej4 ,construction of the ,battery 7,pls4 ,v and ,,vi1 ,figs4 #ec1 #ee1 #fj1 #fg74--,two reliefs are required for this4 ,the first relief receives its tools and arrives upon the ground at dusk4 ,it is divided into four parties1 one for the front ditch1 one for the gun portions1 one for the rear trench1 and a reserve of ten per cent for substitutes and casualties4 ,they are posted and supervised by the engineer officer1 n4 c4 os41 and sappers as described in paragraph #af1 ante4 ,the ,front-ditch ,party4--,each digger is assigned a task #e' wide1 #f' long1 and #c' #f deep4 ,he throws the earth as far into the parapet as he can4 ,the shovellers1 one to each two diggers1 are posted #ab feet from the cutting line of the ditch4 ,they pass the earth back toward the interior crest and the traverse1 keeping the top surface nearly level4 ,the gun-portion party is divided up equally among the gun portions1 each digger is allotted a task #d' wide1 #g' #f long1 and #c' #f deep4 ,the gabions around the gun portion are placed by the shovellers under the direction of the engineer soldiers1 a short one being placed at the throat of the embrasure4 ,the shovellers spread and level the earth thrown out by the gun-portion parties and the rear-trench party4 ,they work in connection with the other shovellers to give to the traverses and parapet near the interior crest the proper shape4 ,the ,rear-trench ,party4--,this party excavates to a width of #g' #f the rear trench and the communications with the parallel or approach4 ,each digger has a task #d' wide1 #g' #f long1 and #c' #f deep4 ,the two directly in rear of each gun portion throw the earth to the rear1 the others throw it to the front1 leaving a berm of #d' #f at the rear of the traverse4 ,the men of the reserve who are not otherwise occupied fill sand-bags from the earth thrown to the rear1 and cut a ramp #h feet wide and not steeper than #a_/d1 in rear of each gun-portion1 when needed4 ,it is essential that the excavation of the gun-portion be finished by the first relief1 so that the platforms may be laid by the second relief in time to allow the guns to be placed before daylight4 ,the first relief leaves in the battery the tools required by the second and carries the rest back to the depot4 ,the second relief is divided into three parties and a strong reserve of one quarter or one fifth of its strength4 ,the first1 or front-ditch party1 works in the front ditch1 widening it #f feet and throwing the earth back to form the front of the parapet4 ,the shovellers1 one to each two diggers1 spread and level it4 ,the task of a digger is #e' wide1 #f' long1 and #c' #f deep4 ,the second1 or platform party1 places the platforms and gives way to the gun detachments4 ,the third1 or rear-trench party1 widens the trench #c' towards the front by cutting off the rear of the traverses4 ,the reserve completes any work left unfinished by the first relief1 fills sand-bags and places them around the gun portions1 digs ditches and drainage-pits when needed1 and does any other work necessary for the completion and arming of the battery4 ,when a tramway is laid in the trench for bringing up the guns and carriages1 the ramps in rear need not be cut4 #ea4 ,alternative ,construction in ,position ,very ,much ,exposed4--,when the earth thrown up in making the splinter-proofs cannot be concealed1 it may attract such a severe fire from the defence as to make the above-described construction impossible4 ,in this case the battery is traced as above described1 the balks for covering the splinter-proofs are placed in position resting on bearing-planks1 and the construction of the front ditch1 gun portions1 and rear trench are commenced at once2 and the battery is as nearly finished as time allows1 and armed if possible4 ,the splinter-proofs are subsequently mined out and the remaining necessary details finished before opening fire4 #eb4 ,splinter-proofs1 in addition to those in the central trench1 are usually constructed under the rear of the traverses 7,pl4 ,,vi1 ,figs4 #fe-fg74 ,these may be made during the construction of the battery or after its completion4 ,they are about #e feet wide1 #f feet deep1 and #aj feet shorter than the width of the traverse4 ,their floor is at #f feet below the surface4 ,the earth is held up by frames and sheeting1 and the roof is supported by cross-balks resting on posts and running back into the traverse4 ,the roof consists of railroad iron or heavy timbers covered with earth1 and access is given by steps from the rear trench2 the space not occupied by the steps may be shielded with inclined posts or other covering if thought necessary4 ,these splinter-proofs differ in no essential from those described in ,field ,fortifications4 ,the finished battery is shown in ,pl4 ,,vi1 ,figs4 #fb-fd4 #ec4 ,sunken ,battery in a ,parallel 7,pl4 ,,vii1 ,figs4 #fh and #fi74--;,a battery similar to the one above described is sometimes constructed in a parallel4 ,in this case the traverses have to be built up1 and therefore do not usually exceed #bj feet in thickness4 ,pickets are driven at intervals of #ce feet along the banquette of the parallel to mark the centres of the gun spaces1 and the rest of the battery is traced in the usual way4 ,the steps of the parallel are cut away and the slope revetted for the gun spaces and the central trench4 ,gabions are placed along the back of the central trench and the sides of the traverses4 ,a rear trench #g' #f wide is cut from the parallel at an easy curve1 so that its front cutting-line shall be #be feet from the foot of the interior slope2 this1 as before1 is widened #c feet by the second relief cutting away the rear of the traverses4 ,the reverse slope of the parallel in rear of the gun portions is cut back to the rear trench4 ,a trench #b feet wide and #b feet deep is cut between the front of the traverses and the foot of the interior slope1 and the cartridge recesses are excavated4 ,the gabions of the traverses are filled1 balks placed over the central trench1 and the tops of the traverses and splinter-proofs are raised to the height of the parapet of the parallel4 ,a ditch in the front of the parallel #ab' wide and #c' #f deep1 traced at dusk1 and excavated during the night1 supplies earth to make the parapet #cj' thick and #d' #f high4 ,the work done in and behind the parallel is not seen from the front1 hence a great part of it may be done by day1 undetected by the enemy4 ,the upper part of the traverses is made by night1 and the front ditch and front of the parapet are made the same night or subsequently1 depending upon the number of workmen available4 ,since the gabions of the traverses seriously obstruct the parallel1 they should not be placed in position until all arrangements are made to open the rear trench4 ,in the special case of a battery on the crowning of the covered way1 the traverses have been already constructed in running the sap4 ,the splinter-proofs may be constructed by blinding portions of the sap1 or by mining them under the traverses4 ,owing to the height of the parapet1 embrasures of some depth will have to be cut through it4 ,this is done by a shallow sap started by one man1 who is subsequently assisted by a second1 if the splay requires it4 ,the cheeks are revetted with sand-bags1 covered with hides4 ,the mouth of the embrasure is left closed with the head parapet of the sap until fire is to be opened1 when the earth is dug away or blown away by the gun4 #ed4 ,battery ,behind the ,crest of a ,hill 7,pl4 ,v41 ,figs4 #eg-ei74--;,in a battery behind the crest of a hill the front ditch may be omitted1 the gun-portions may be entirely in excavation1 and the platforms given such a reference as to require a shallow groove to be cut through the crest to allow the gun to fire4 ,when the ground falls away very rapidly to the rear it may be stepped under the traverses to prevent their sliding1 and the rear of the gun emplacement may be raised when necessary to give the platform the proper slope4 ,the central trench is cut deep enough to give #e feet of cover over the splinter-proofs4 #ee4 ,batteries on ,sloping ,ground 7,pl4 ,,vii41 ,figs4 #gj-gb74--,when the ground to be occupied by the battery slopes towards or from the place or falls off on either side1 the battery is constructed essentially as upon level ground4 ,the central passage is driven1 following the surface of the ground1 the gun emplacements1 front and rear trench are excavated as before described1 the additional excavation or filling required in each gun emplacement to make the platform horizontal is regulated for the particular site1 any excess of earth being used to give greater cover on the more exposed side1 and any deficiency being supplied from the front or rear trench1 as may be most convenient4 ,where the extra work imposed by the slope is considerable1 a third relief may be required to finish the battery1 and its arming may be necessarily postponed until the next night4 #ef4 ,embrasures4--,modern siege guns are generally mounted either on 8overbank0 or 8disappearing0 carriages1 firing over parapets of sufficient height to give cover to the men4 7,the axis of the trunnions of the ,u4 ,s4 #e siege gun is #f above the platform47 ,embrasures when used are generally shallow grooves cut in the top of the parapet4 ,in this case the bottom of these grooves must cut the surface of the top of the parapet at or in rear of the highest line visible to the enemy1 so that no indentations which can be seen by him will indicate the position of the guns4 ,to effect this1 the exterior crest will usually be as high as and sometimes higher than the interior crest1 and the top of the parapet 78superior slope07 will be level or will slope to the rear4 ,in rare instances1 however1 deeper embrasures with revetted cheeks must be made4 ,the only serviceable revetment for use with high-power guns is one of sand-bags wrapped in raw hides4 ,this may be made by laying down a hide1 piling a number of sand-bags upon it1 and folding the free end back over them2 placing another hide on top of this with more sand-bags and so on4 ,or large packages may be made by wrapping up a number of sand-bags in each hide and these packages may be used for making the revetment4 ,the embrasure should be bottle-shaped in plan1 shaped like a segment of an ellipsoid immediately in front of the muzzle of the gun1 then drawn in like the neck of a bottle and narrowed to as small a mouth as possible1 so as to diminish the effect of the blast and give the least possible exposure to the gun4 ,when the battery is exposed to slant or enfilading fire1 instead of embrasures1 bonnets of sand-bags may be built upon the parapets to protect the guns4 #eg4 ,observatories4--,observatories or look-outs1 as previously stated1 should as a rule be placed on high points well on the flanks of the battery4#b ,when this is impracticable1 they may be made by building up at the rear of the traverses1 on the flanks1 or even in the gun portions1 glacis-shaped covers pierced with a sight-hole in all respects similar to a loop-hole for musketry1 and with just sufficient splay to include the desired field of view4 ,a number of these should be provided for each battery1 so that the enemy may not know which one is in use at any time4 ,if subject to close and accurate fire1 the crest-line in their vicinity must be of the same level as the tops of the look-outs1 and provision must be made to prevent the light showing through them4 #eh4 ,drainage4--,after the completion and arming of the battery1 gutters should be cut on each side of the gun-portion leading into one running along the reverse of the rear trench which carries the water to low ground on the exterior1 or which is provided with dry wells or drainage-pits for collecting the water so that it may soak into the ground or be pumped out with hand-pumps4 #ei4 ,mortar ,batteries4--,the introduction of rifled mortars of all calibres1 with the corresponding increase in accuracy of fire1 together with the destructive effects of shells charged with high explosives1 will doubtless lead to the extensive use of mortars in future sieges4 ,in a distant attack the requirements of a mortar battery are very simple1 consisting principally of a stable platform1 magazines for ammunition1 and bomb-proof covers for the gunners2 since the battery as a rule will be concealed from the view of the work by intervening obstacles1 and will in consequence not be subject to direct fire4 ,when the soil is favorable1 cover against plunging fire will be most easily obtained by sinking pits for the mortars to such depth as may be necessary to furnish earth for a splinter-proof parapet surrounding the pit1 and for cover for the bomb-proof shelters for the men and the magazines4 ,when ample space exists which is well concealed1 and in which the soil is good1 a separate emplacement should be made for each mortar4 ,when necessary1 however1 two or more mortars may be placed in each pit4 ,the magazines1 splinter and bomb proofs are similar to those elsewhere described4 ,when no natural mask exists1 the battery may be constructed behind an artificial screen1 and be made of the general type of the 8exposed siege battery10 the gun portions being made with front enough to accommodate one or two mortars as may be preferred1 and of such length only as is needed for working the mortar employed4 ,the terre-plein may be placed at any convenient depth below the surface of the ground1 and the revetment of the interior slope1 if any be used1 will not ordinarily be carried higher than the muzzle of the mortar4 ,as the traverses are not subject to gun-fire1 the splinter-proofs afforded by the central passage may be added to by building others along both sides of the traverse2 and by deepening the mortar emplacement sufficiently1 they may be given enough cover to make them true bomb-proofs4 ,a mortar battery fulfilling these conditions can hardly be silenced by hostile fire4 ,the conditions under which the batteries may be constructed are1 however1 so varied that detailed dimensions will not be given4 ,no difficulty will exist in making the battery of a size suitable for the pieces to be employed4 ,the ,u4 ,s4 rifled siege mortar is of #g-;inch calibre1 about #e feet long1 weighs #agae lbs41 and is designed to throw a #abe-lb4 shell with a charge of #e lbs4 of powder1 giving an initial velocity of #fhe f4s4 and a range of about #djjj yards4 ,with reduced charges the range may be reduced to about #fej yards without undue sacrifice of accuracy4 ,in the closer attack upon the work1 batteries for the smaller siege and field mortars may be readily constructed in front or rear of the parallels1 or in the parallels or approaches themselves2 splinter-proofs and temporary magazines being constructed by methods previously indicated4 ,in many cases1 however1 the lighter mortars1 field and ,coehorn1 which do not require fixed platforms1 may be placed behind any part of the trenches affording cover1 and fire be opened and continued until the fire of the enemy becomes too annoying1 when the mortars may be removed to some other locality4 ,,magazines4 #fj4 ,magazines should be provided1 at least two to each battery1 not only to localize the injury due to an explosion1 but also to prevent the battery being disabled by the explosion of a single one4 ,as previously stated 7par4 #dc71 they should contain #bd hours' supply 7from #aej to #bjj rounds7 for each gun which they are designed to serve1#c which may require a capacity in a single magazine of as much as #f1jjj lbs4 of powder4 ,this amount should be reduced when possible by increasing the number of magazines4 ,the cartridges should be made up and packed in boxes at the depots or parks1 and the powder chambers in the magazines should be of such size as to store these boxes with only such vacant space as is necessary for ease in handling them4#d #fa4 ,cover4--,the chamber should be covered with strong balks or rails and enough earth to form a sloping roof2 over this raw hides or tarpaulin should be spread1 and the remainder of the earth filling be spread upon this and rammed solidly4 ,the amount of earth cover required for security must be determined from the principles given in par4 #ba4 ,the ,english engineers recommend as sufficient protection against ordinary fire for a magazine #e feet wide1 two layers of #i #i fir laid crossing each other1 or one layer of #ab #ab oak1 covered with #e feet of earth4 ,in experiments at ,lydd in #ahhc1 however1 an #h-;inch howitzer shell falling at an angle of about #cj penetrated through a covering of #g feet of soft clay and burst upon the timber roof of a magazine1 cutting it through4 ,this shows that complete protection is not always possible1 and that the chances of hitting must be reduced by making the horizontal area of the magazine chamber as small as possible1 and placing its smaller dimension in the line of the hostile fire4 ,the clear height of the magazine should be #d' #f to #e' minimum1 when practicable1 and the top of the covering balks should be at or below the level of the ground4 #fb4 ,location4--,a magazine should be located at such distance from the battery that its explosion will not disable the guns1 injure the parapets or traverses1 or seriously endanger the cannoneers2#e but1 on the other hand1 it should be near enough to allow the ammunition boxes to be conveniently carried to the cartridge recesses2 and the communications for this purpose should be well covered from hostile fire4 ,the entrance to the magazine should be so protected that splinters cannot enter the chamber4 ,any natural hollows1 banks1 etc41 in the immediate vicinity of the battery should be taken advantage of to facilitate the construction of and give better cover to the magazines4 ,when nothing of this kind exists the magazines may be placed on the flanks or in rear of the battery1 and should be masked and screened by the parapet of the parallel1 approach1 communications1 or battery1 or by special glacis-shaped screens made1 for the purpose2 which should be much longer than the width of the magazines that they cover1 so that the discovery of the location of the latter by the enemy may be made more difficult4 ,the magazines should not be located in rear of the centre of the screens nor symmetrically with reference to the battery1 nor1 when it can be avoided1 directly in rear of a gun4 ,the passages leading to them should enter the battery in rear of a flank or a traverse1 and should be so directed as to escape enfilade4 ,they should be so graded that the surface water will run away from the door of the magazine and be discharged upon lower ground or received in drainage-pits placed at the lowest points4 #fc4 ,construction of a ,magazine ,subject to ,direct ,fire ,only 7,pl4 ,,vii41 ,figs4 #gc-gg47--,the method of tracing the magazine and its approaches is too evident to need description4 ,in this example an earth cover of #e feet against vertical and #bj feet against horizontal fire is given4 ,should more or less be desired1 a corresponding change may be made in the plan1 depth of excavation1 and depth and width of approaches2 and the earth for additional cover may be obtained from a ditch or pit in rear of the magazine4 ,the excavation for the chamber is given a width of #f'1 a depth of #e' #f1 and a length of #ab'1 the entrance a width of #c'1 a depth of #e' #f1 and a length of #f'4 ,the sides of the chamber and entrance are held up by frames #d' #i high and #b' #aa wide1 outside measurement4 ,the caps are #f #e1 stanchions #d #e1 and the ground sills #c #e2 sheeting #a thick is inserted between the frames and the earth4 ,the covering balks are #i #f and #aj feet long2 their tops are flush with the surface of the ground2 cleats nailed on their under side keep the tops of the side frames from being pushed in by the pressure of the earth4 ,the earth cover is #e feet high at the centre and #d feet at the crest of the outer slope4 ,the passages are #e' #f deep1 #c' wide at bottom1 and #e' at the top4 ,the entrance is blinded by placing balks across the passage for such part of its length as may be thought necessary1 and extending the earth covering over them1 as shown in the section 7,fig4 #ge74 ,a door1 swinging outside1 is hung on the outside frame4 ,heavy railroad iron may be substituted for the timber balks with advantage4 ,when thicker balks are used1 or when a second layer is added1 the chamber and passage should be correspondingly deepened4 #fd4 ,manner of ,executing the ,work4--,the powder chamber and passage are excavated and the frames and balks placed during the first night1 while the central passage of the battery is being constructed4 ,the excavated earth is thrown out far enough to allow the balks to be put in position1 and is so spread as not to be seen by the defence4 ,this may be done by one relief of #h hours1 or two reliefs of #d hours each4 ,if the work is not completed during the night1 the sheeting1 frames1 and balks may be placed by day under cover of the earth thrown out and the existing screens4 ,the passages are excavated and the earth cover completed on the second night by two #d-;hour reliefs1 the first excavating to a depth of #c' #f1 and the second to #e' #f1 trimming up the slopes and completing the work4 ,when necessary1 the sides of the passage will be revetted by the second and a third relief4 ,when the necessity for great haste exists1 the excavation of the powder-chamber1 entrance1 and passages may be carried on at the same time1 the excavated earth being thrown in front and on the sides of the powder-chamber until the balks are in position1 and then thrown back upon them1 levelled and rammed4 #fe4 ,mined ,magazine4--,when the soil1 by absence of rock and water1 admits of mining1 greater cover against vertical fire can be obtained with less work by mining out the powder-chamber and passages 7,pl4 ,,viii1 ,figs4 #gh1 #gi74 ,the figures illustrate one of minimum dimensions1 which is constructed as follows3 ,the entrance #aj' #e' by #e' #f deep is first excavated1 revetted with frames and sheeting and covered with balks and earth as indicated4 ,at #a foot from the end a shaft #b' #e' is sunk to a depth of #ab'4 ,from the front of this a gallery #b' #e' #f is driven for about #f'2 at the end of this galleries #e' #f #b' are broken out on each side and driven so far as may be necessary to store the requisite number of ammunition-boxes4 7,for method of sinking shafts1 driving galleries1 etc41 see ,military ,mining1 ,arts4 #be1 #cc1 and #dd-dh47 ,the excavated earth is spread on top of the magazine to increase the thickness of the cover already given by that excavated from the passages4 ,a ring-bolt is placed in the balk directly over the shaft1 for attaching a hoisting tackle for removing the earth during construction and for hoisting and lowering ammunition-boxes afterward4 ,a door opening outward may be hung at the entrance1 and the passage may be blinded as previously described1 if it is thought necessary4 ,the communications are arranged in essentially the same way as for the magazine previously described4 ,the dimensions given are the least which will allow moderately free access and good cover4 ,the magazine should be constructed1 by good miners1 in two nights and the intervening day1 and will store about #djjj pounds of cartridges in boxes4 ,when time and the character of the ground admit1 and larger capacity is desired1 the shaft may be made wider and deeper1 the gallery wider and longer1 and the powder-chamber deeper1 longer1 and wider1 if desired4 ,the excavation for the entrance and approaches1 the placing of balks1 and the levelling and ramming of the earth-cover1 should be done by night2 the mining work can be carried on both night and day4 #ff4 ,elevated ,magazines4--,when the presence of rock or water in the soil prevents sinking the magazines to the full depth above given1 they must be sunk so far as practicable and given the least possible clear height of powder chamber1 with the best attainable overhead cover4 ,this should be strengthened by the use of railroad iron or rolled iron beams1 when available4 ,the cover against direct fire should be increased up to #cj feet1 and the front slope be made gentle1 like a glacis4 ,a screen made of an earthen bank with a glacis slope should also be used if possible4 ,these precautions having been taken1 the depth of the powder-chamber in the direction of the hostile fire should be reduced to a minimum1 and the storage of large quantities of powder be avoided1 so far as possible1 by constructing a number of small magazines at the most convenient places in the vicinity of the battery4 #fg4 ,precautions against ,dampness in ,magazines for ,siege ,batteries4--,underground magazines of the character above described are1 of necessity1 sometimes damp4 ,the only ventilation usually possible is obtained by leaving the door open1 the air being changed more or less by the men going in and out4 ,the passage leading to the powder-chamber should enter it at the middle1 and in the service of the guns one half of the chamber should be emptied on one day and the other half on the next4 ,this will usually limit the time which a cartridge is exposed to the dampness of the magazine to a maximum of one or two days4 ,,chapter ,v4 ,,siege ,,operations4 ,,the ,,attack4 #fh4 ,siege operations include all the steps taken from the first approach to the work up to its final capture4 ,these taken in regular order are as stated in ,chapter ,,ii3 the investment1 the distant artillery attack1 the construction of approaches and parallels1 breaching by artillery or mines1 and the final assault4 ,for convenience in description the siege has been divided into three periods4 ,the first period includes the preliminary operations up to the completion of the investment4 ,the second period includes all the operations between breaking ground for the batteries of the first artillery position and the first parallel1 up to the completion of the most advanced parallel and the occupation of a position near the foot of the glacis from which the attack is to be made upon the breach1 either by assault or sap4 ,the third period comprises the advance from the last parallel1 and all subsequent operations up to the capture of the last entrenchment and the surrender of the garrison4 ,the first and second periods are sometimes known as the 8distant0 and the third period as the 8close attack40 ,,first ,,period4 #fi4 ,as a preliminary to the siege of any fortified place1 all possible information is obtained as to the strength and character of its fortifications1 the garrison1 armament1 stores of provisions and ammunitions1 water supply1 water routes1 telegraph and railroad lines1 manufactures1 especially those which may be converted into factories of arms and munitions1 the character of the population of the place1 their probable food supply and their loyalty to their state2 also the topographical features and nature of the ground in the vicinity of the work1 the sites of camps and parks1 the prevalent diseases of the locality and the best means of preventing their attacks1 etc41 etc4 7see ,bureau of ,intelligence1 ,art of ,war1 par4 #abh74 ,from these data the necessary materials and supplies are collected at convenient points1 the railroad or water routes selected1 and the cars1 boats1 wagons1 etc41 for their transportation provided2 so that they may arrive promptly and in the proper order when needed4 #gj4 ,the ,investment4--,the investing force is brought together1 organized1 and moved rapidly upon the place4 ,when it is available a large force of mounted troops may be used advantageously in the investment1 and be subsequently relieved by infantry and artillery4 ,when the investment is made1 it adds greatly to the advantage of the attack to completely surround and isolate the work1 and to push the investing line as near it as possible4 ,when the investing force is more or less dispersed1 and is to be concentrated for the siege1 the temptation frequently exists to march them by converging lines upon the place as a point of concentration4 ,while this may be advisable in some cases 7as where the garrison is very weak or under an inefficient commander71 it will usually expose the subdivisions of the investing force to be beaten in detail 7,art of ,war1 par4 #cib74 ,so also in surrounding the place2 a premature subdivision of the force into small fractions not protected by field-works1 or not within supporting distance each other1 will afford to an active defence an opportunity1 by well-conducted sorties1 to inflict most severe losses upon the attack and very greatly delay the investment4 ,keeping these dangers in view1 the investing force will move rapidly upon the work1 seize1 strengthen1 and occupy strong points as near the work as possible1 and extend the lines to right and left as rapidly as good judgment allows1 until the place is surrounded4 ,meanwhile detachments of greater or less size will scour the ground around the place1 seizing and carrying off or destroying1 so far as possible1 all cattle1 grain1 lumber1 etc41 and everything else which would be of use to the attack or defence4 ,under cover of these detachments and escorts specially detailed for the purpose1 reconnoissances will be made to cover so much of the ground as can be reached1 especial efforts being made to examine the ground near the works4 ,these reconnoissances will necessarily be hurried and incomplete but1 must be as accurate as they can be made under the circumstances4 ,they should be directed principally to determining the heights and directions of the principal points of the works1 and their positions with reference to prominent points that may be used as landmarks1 in verifying and correcting maps and information previously obtained1 to discovering the existing armament of the place and the steps already taken for its defence1 and to collecting all possible information bearing upon the selection of the front of attack4 ,systematic reconnoissances and surveys carried on throughout the siege must be relied upon for checking and completing the work thus begun4 ,so soon as the supporting points for the investing force are secured1 a line of outposts is pushed forward towards the work and sentinels1 pickets1 etc41 are established 7,art of ,war1 pars4 #afg-aid74 ,the lines of sentinels1 pickets1 and supports are placed as near the work as practicable1 and the line of resistance is advanced at every favorable opportunity4 ,the usual rules for posting and relieving the outposts1 establishing day and night cordons1 the use of patrols1 etc41 are applied1 with such modifications as circumstances render advantageous4 ,any advanced points affording marked advantage to the attack which have been seized are strengthened and held when possible1 even at considerable cost in men or with some delay in completing the investment4 #ga4 ,bringing up and ,posting the ,besieging ,force4--,the main besieging force1 consisting principally of infantry1 artillery1 and engineers1 with the siege train1 follows closely after the investing force1 and1 upon arrival is encamped upon sites previously selected1 sending out at once1 however1 such reinforcements and supports as are needed by the line of investment4 ,engineer and artillery parks are established outside the zone of fire of the works and in proximity to the main routes of communication4 ,branch railways and tram-roads running through the parks1 storehouses1 repair shops1 etc4 etc41 are located and constructed4 ,sites for storage magazines for ammunition are carefully selected at the most secure places1 and isolated when possible from the camps and parks by intervening elevations of ground4 ,the cover of these magazines1 so far as possible1 is made up of wood and sand or earth free from stones large enough to be dangerous projectiles in case of explosion4 ,rooms for loaded shells and cartridges1 and laboratories for making up ammunition are constructed upon similar principles4 ,carefully studied arrangements for the health and comfort of the men are made4 ,some of these are outlined in ,chapter ,,vii4 #gb4 ,fortifying the ,camps1 ,parks1 etc41 etc4--,in former sieges it was customary to completely surround the ground occupied by the besieger with a continuous line of works of simple trace and light profile called the 8line of circumvallation20 and to construct between the camps and the work another line1 either continuous or with intervals1 called the 8line of countervallation40 ,these lines were placed respectively at about #bjj yards in rear and in front of the camps4 ,the principal object of the first was to prevent by a small force the entry of small reinforcing detachments and supplies2 that of the second was to resist vigorous sorties by the defence1 or sudden attacks from the outside by strong reinforcing parties4 ,for this purpose the detached works of the line of countervallation were so disposed as to cover the main depots1 parks1 roads1 etc41 and to be in defensive relations with each other4 ,the great development of the line which must be occupied by the besieger1 owing to modern methods of fortification and the range of rifled cannon1 prohibits the construction of complete lines of circum- and countervallation4 ,the besieger constructs in their stead one or more lines of detached works upon advantageous points1 and covers the intervening ground more or less thoroughly by patrols1 outposts1 etc4 ,he then so disposes his main force as to be able to concentrate enough to meet any sorties of the defence2 and1 if necessary1 detaches a force1 called an 8army of observation10 sufficiently large to meet any relieving army and defeat it2 or hold it in check until he can concentrate the besieging force with the army of observation1 and meet the relieving army in a favorable position4 ,as a rule1 this position will be one well outside the besieger's cordon of works2 since the latter by its extent will necessarily be weak to resist a determined attack 7,art of ,war1 par4 #beh71 and by its proximity to the work will render possible the co-operation of the garrison and the relieving army4 ,this1 under the circumstances assumed1 would seriously endanger the besieging army4 ,in opposing sorties from the work1 however1 the conditions which fix the point of conflict are reversed1 and place it as near the work as practicable4 ,the shortening and strengthening of the line of investment by closing it in upon the work make it imperative to hold all ground gained2 and this is generally best accomplished by intrenching the line of outposts with continuous shelter trenches1 strengthened at intervals by batteries of field guns1 and supported by field works of considerable strength1 placed within accurate cannon range of each other1 but not exposed to the direct fire of the guns of the place4 ,behind the shelter trenches the outposts1 supports1 and reserves1 strengthened when necessary by troops from other points of the line1 should be able to hold their own against all ordinary sorties4 ,the main line of field works serves to resist a general attack made by the mass of the garrison4 ,placing the first intrenchments further back exposes the outposts to the confusion resulting from falling back1 frequently at night or in a fog1 and also enables the besieged to seize upon ground from which it may be very difficult to dislodge them4 ,to allow the different parts of the line to be rapidly reinforced1 good roads protected from the fire of the work1 and well marked with sign-posts1 etc41 must be opened between the adjacent divisions of the besieging force1 and all streams must be provided with bridges secure against floods1 ice1 etc4 #gc4 ,distance of the ,line of ,investment from the ,work4--,this will result from conflicting conditions4 ,reasons already given1 which need not be repeated1 lead to establishing it as near as practicable4 ,on the other hand1 the accurate fire of the heavy guns of the place1 and vigorous sorties by the defence1 cause much annoyance and great loss to a line drawn too near the work4 ,the more recent sieges indicate about #cjjj yards from the most advanced works1 as the least distance for the line of investment in open country and with an active defence4 ,it may be necessary in some cases to increase this to #dejj or #ejjj yards2 but with ground favorable to the attack1 and a weak and demoralized defence1 it may frequently be drawn nearer4 #gd4 ,strength and ,composition of the ,besieging ,force4--,in former sieges when the place held out until the inner keep was breached and carried by the regular progress of the siege1 the ratio of the necessary strength of the attack to the defence was estimated at #g or #h to #a1 this large ratio resulting from the excessive labor in the trenches and the losses incurred on the close attack4 ,modern writers 7arguing largely upon theoretical considerations7 have reduced this estimate to #d or #e to #a4 ,no attack on a thoroughly-equipped and well-defended strong place having been carried through all the steps of a regular siege since the introduction of modern arms1 absolute data upon this subject are lacking4 ,the besieging force at ,strasburg was about #fj1jjj1 garrison about #bj1jjj1 total length of siege #di days4 ,the defence was very weak4 ,belfort1 besieging force about #cb1jjj1 garrison about #af1jjj4 ,after a siege of #ajj days the approaches were at about #abjj yards from the works1 which capitulated by reason of the general surrender of the ,french4 ,at ,metz the besieging force was #aej1jjj men2 the garrison1 demoralized by the previous defeat at ,gravelotte1 surrendered #agc1jjj men4 ,at ,paris the investing force was about #ahj1jjj1 and the garrison nominally between #cjj1jjj and #djj1jjj1 of which perhaps #cj1jjj were disciplined and effective soldiers2 the remainder being made up of remnants of defeated regiments and bodies of the ,garde ,mobile and ,garde ,nationale4 ,the investment of ,paris was complete on ,september #ai1 #ahgj2 its surrender from exhaustion of provisions took place ,january #bi1 #ahga4 ,several sorties were made1 but the general defence was paralyzed by the character of the troops and inhabitants4 ,at ,plevna the ,turks had at the outset about #ef1jjj men1 at the surrender #dj1jjj4 ,the ,russian force suffered great losses in its assaults1 but by continual reinforcement had at the end of the siege about #abj1jjj men4 ,the defence by the ,turks was desperate1 but generally passive4 ,one determined sortie was made immediately before the surrender4 ,the surrender resulted from exhaustion of ammunition and provisions4 ,the works were field works only4 ,at ,belfort the investing force was at first but #aj1jjj and the line of investment #be miles long1 giving but #djj men to the mile4 ,this force was subsequently increased to #bj1jjj men1 and when the besieging army had all arrived1 to #cb1jjj men4 ,at ,paris 7#ahgj7 the line of investment was about #c miles from the line of the forts1 and about #ec miles in length1 the investing force #ahj1jjj1 giving a mean of about #b men to the yard4 ,the distribution was1 however1 about #d to the yard on the left bank and #a on the right bank of the ,seine4 ,at ,plevna the line of investment was #b miles from the forts1 its length #dc miles1 the investing force #ajj1jjj men1 about #a men to the yard4 ,in each of these sieges the place finally fell under the attack of a force1 in no case equal to #b times the garrison2 but inferences drawn from this fact are apt to be erroneous1 since none of these places was well fortified according to modern methods1 well garrisoned1 well supplied1 and defended to extremity4 ,the results show1 however1 that under similar circumstances1 which are apt to arise in any modern war1 the attack of a strong place which can be completely invested by a force of two or three times the strength of the garrison1 may promise success2 which seems to be assured if the defence allows the besieging force to complete the investment and thoroughly intrench itself4 ,on the other hand1 tactical considerations would indicate that a well-equipped army1 of good morale1 under an active and aggressive commander1 covered by a modern intrenched camp1 should be able to prevent the investment2 and by taking advantage of its interior lines1 its heavy guns and its strong points d'appui1 should be able to beat in detail a force very much greater than itself whose fractions1 by reason of the extent of the line of investment1 are necessarily not within supporting distance of each other4 ,these advantages of the defence evidently disappear1 as above indicated1 when the attack is allowed to complete its fortifications1 since under their cover a small force can check even a determined sortie until a sufficient force to beat it can be concentrated4 ,from these considerations it is evident that an investment1 once completed1 may be maintained by a force less than that necessary to establish it in the first place 7see ,investment of ,plevna1 ,pierron1 ,mthodes de ,guerre ,vol4 ,,iii1 pp4 #fdg et seq474 #ge4 ,the ,point of ,attack4--,from the information originally in possession of the besieger1 supplemented by that obtained by reconnoissance1 a decision is made as to the fronts of the work or the particular detached works of the intrenched camp upon which the approaches are to be made4 ,the portion selected in either case is called the 8point of attack40 ,to reduce an intrenched camp1 it will in general be necessary to capture at least two of the detached works and to silence the artillery fire of one or more on each side of those taken4 ,in an attack upon a strongly-fortified enceinte1 the least that is usually undertaken is to breach and capture one front with its adjacent outworks1 and to silence the fire of those which enfilade the approaches and parallels or take them in reverse4 ,in selecting the point of attack the first consideration is1 that when taken1 it shall afford material advantage to the besieger and give him a foothold from which further approaches may be driven1 if necessary4 ,this condition being fulfilled1 the choice will result from a careful study of the nature of the works and site4 ,those forts or fronts resting upon precipices1 bordering deep marshes or deep and rapid streams1 or which are so placed that approaches upon them will be swept in flank and rear by the fire of the works1 which cannot be silenced1 are considered impregnable by the ordinary operations of the siege4 ,most serious difficulties are presented by those in which the adjacent works are so disposed and of such strength that they can be carried only in succession and by regular approaches2 those provided with wet ditches in which strong currents can be produced1 those with dry deep ditches1 those which are mined1 and those which present long lines nearly straight1 or even concave to the attack1 and covering a front nearly equal or even greater than can be occupied by the trenches of the besiegers4 ,when the parallels and approaches have to be constructed upon ground sloping downward towards the work1 in soil containing large stones1 or in which the rock is close to the surface1 in marshy ground or that containing much water or liable to be flooded1 the difficulty of their construction and defilade are evident4 ,the point of attack considered most favorable to the besieger is one which1 fulfilling the first essential condition1 is more or less salient1 so that it can be partially surrounded1 and which admits of the approaches being driven toward it in favorable soil1 over ground sloping gently from the work1 or gently rolling with the crests and valleys of sufficient difference of level to afford cover1 and running generally in the direction of the parallels4 ,a favorable location for parks1 etc41 with free1 safe1 and short communications between them1 also has great weight in selecting the point of attack4 ,,second ,,period4 #gf4 ,first ,artillery ,position4--,every siege begins with a bombardment1 which is designed1 as previously stated1 to drive in the outlying posts of the defence1 to silence1 so far as possible1 the artillery annoy and wear out the garrisons of the works to be attacked1 to interrupt the communications between them1 break up bomb and splinter proofs1 destroy magazines and depots1 and1 if the enceinte can be reached by the artillery1 to bring a fire upon the population which will lead to or hasten the surrender of the place4 ,the considerations which determine the location of the batteries for the general bombardment have already been given 7par4 #g71 as well as the construction of the batteries and screens used 7,chap4 ,,iv474 ,for the systematic attack1 however1 the necessity of dismounting or silencing the guns bearing upon the proposed approaches introduces the additional condition that the batteries should be so located that besides their general effect each shall fulfil1 so far as practicable1 its special design by bringing an enfilading or reverse fire upon certain fronts2 or1 in connection with other batteries1 shall keep down the fire of certain fronts by a preponderance of direct fire4 ,many batteries which fulfil these last conditions occupy their original positions during the entire siege4 ,the requisite concentration of fire upon the point of attack and its careful regulation for the special object in view will frequently restrict the arc occupied by the batteries below that desirable for a general bombardment only2 and will necessitate a closer grouping of the batteries for their easier control by the artillery commanders4 ,this line of batteries first established is known as the 8first artillery position0 7,pl4 ,,viii41 ,figs4 #hj1 #ha74 ,as the batteries must be secure against the attacks of the defence1 they must of necessity be outside the besiegers defensive line4 ,their distance in yards will result from the character of the defence and may vary from #bjjj or #bejj yards for a weak defence1 to #cejj or #dejj yards for an active one4 ,on account of their long range and the object to be obtained by their fire1 they are armed with the heaviest rifles and howitzers available1 supplemented with rifled mortars of as large calibre as can be obtained1 firing1 if practicable1 torpedo shells charged with high explosives4 ,batteries of field guns which have already been favorably located for the defence of the heavier batteries against attack1 or for firing upon the more advanced works1 may1 by modification of their gun pits into finished batteries 7par4 #dd71 be used in conjunction with the heavy batteries of the first artillery position4 ,the total number of guns employed should be such as to give to the attack a marked superiority over the defence at the opening of the bombardment4 #gg4 ,opening ,fire4--,the batteries having been completed and armed1 the magazines finished and supplied1 and the parks1 depots and communications put in such order that the batteries can be kept fully supplied with ammunition2 the fire of the batteries is commenced simultaneously1 the signal being given by a gun from some selected battery4 ,the fire once opened is continued day and night during the siege1 unless stopped by the commanding officer or from inability to keep it up4 ,it usually begins at daylight1 in order to enable the ranges to be corrected by the first shots1 before the defence has accurately located the batteries unmasked during the preceding night4 ,to open fire from a few batteries before the others are ready is inexcusable1 as it enables the defence to concentrate its fire upon them and destroy them in succession4 ,the targets of each battery and gun and the rate of fire are prescribed before the fire is opened1 and these are changed only by subsequent orders or from sudden emergencies4 ,the fire is as a rule deliberate1 seldom exceeding an average of #d shots per hour for each gun by day1 and #b per hour at night4 ,this rate may be increased or diminished by the commanding officer for special reasons and for a limited time4 ,the fire of the batteries is directed upon all the works of the place within range1 but with greater vigor upon the more important1 and especially upon those near the point of attack4 ,the fire against powder-magazines and storehouses should be uninterrupted1 to prevent the removal of powder and munitions4 ,if the artillery of a part of the work is silenced1 the fire upon it may be slackened1 but some fire1 especially vertical1 should be kept up4 ,at night the fire is directed against the larger targets1 such as communications and covers1 rather than upon the guns2 but the fire against the interior of the place 7especially a city7 is kept at about the same rate day and night4 ,if preparations for a sortie are detected1 the fire of the large pieces is directed at the points of assembly1 when known1 and at the openings through which the sortie is to be made4 ,the field guns direct their fire upon the troops in accordance with the tactical use of this arm4 ,if the batteries of the first artillery position have the proper preponderance over those of the place1 they should soon clear away the advanced posts1 and keep down the fire of the works so that the besieger may advance his outposts1 control the exterior ground and prepare to open the first parallel and establish the second artillery position4 #gh4 ,plan of ,attack4--,by this time the reconnoissances and surveys should be so far advanced and so thoroughly checked up that the chief engineer will have been able to make1 upon a large scale1 a map of the place and its surroundings with considerable accuracy1 and to locate upon it the proposed position of the first and second parallels1 the approaches1 and the batteries of the second artillery position4 ,this map1 with the accompanying memoirs1 makes up the 8plan of attack10 which1 when approved by the commanding general1 serves as a working plan for the prosecution of the siege1 and is continually corrected and added to as the siege progresses4 ,this map should be made in duplicate at least1 and for accuracy in the history of the siege should be corrected so far as possible by redrawing or tracing1 instead of by erasures4 #gi4 ,the ,first ,parallel4--,the first parallel 7,pl4 ,,viii1 ,figs4 #hj and #ha7 serves as an intrenchment for the troops who protect the second artillery position and who cover the workmen driving the approaches4 ,it also affords a covered communication between the different lines of approaches4 ,its length must be sufficient to cover all the batteries of the second artillery position and protect their flanks2 it must therefore extend beyond the batteries which enfilade those faces of the fronts attacked whose prolongations fall furthest out4 ,its flanks are usually more or less refused1 and terminated by strong earthworks4 ,emplacements for batteries of field guns are provided at intervals to assist the infantry in repelling sorties4 ,when the length of the parallel is very great1 it is sometimes not continuous when first opened1 but the portions covering the groups of batteries are first made and are subsequently connected4 ,the ground between them is protected1 meanwhile1 by a strong fire of small arms1 field and other guns4 ,when communications covered by natural screens do not exist between the first parallel1 the batteries of the first artillery position1 and the parks1 approaches are constructed at the same time as the parallel1 in sufficient number to give free passage to the troops1 guns1 and materials4 ,these approaches 7,pl4 ,,viii1 ,figs4 #hj and #ha71 as all others 7par4 #ac71 are so directed as not to be enfiladed by the fire of the work1 and should be provided with portable or other tramways and cars1 passing switches being placed in the returns where needed4 ,its ,distance from the ,work4--,as a rule1 it may be stated that the first parallel is placed as near the work as possible4 ,most of the batteries of the second artillery position are from #ajj to #cjj yards in its rear1 and the shorter their range the more effective is their fire4 ,the small-arm fire from the first parallel may also be an important feature in modern sieges2 to make it so requires the parallel to be located within #aejj yards of the work1 if possible4 ,by placing the parallel as near the work as possible1 its length and that of the saps are correspondingly reduced1 the amount of work lessened1 and generally the fall of the place hastened4 ,if an attempt be made to place it too close to the work1 however1 the working parties will be discovered2 they will be within reach of strong sorties1 and of the deadly fire of small arms and machine guns2 in consequence of which they may suffer very great losses1 be driven off1 and the construction of the parallel prevented4 ,the minimum distance under the most favorable circumstances is then about #fjj to #gjj yards4 7,this was the distance prescribed in the day of smooth-bore guns1 and was adopted as recently as #ahgj at the siege of ,strasburg47 ,in an open1 level country it may not be possible to place the first parallel at a distance from the most advanced work of less than #ahjj to #bjjj yards4 ,when1 however1 it is necessary to establish the first parallel at a very great distance1 it will not1 as a rule1 be made continuous1 but in fractions covering approaches which are driven forward4 ,the first continuous parallel is then built at from #ajjj to #abjj yards from the works1 and behind this the second artillery position is established4 #hj4 ,opening the ,parallel4--,the profile of the parallel is one of those already given 7,pl4 ,i1 ,figs4 #g-ac71 and it is traced and constructed as described 7pars4 #ad1 #ah1 and #ai71 by simple trench1 flying sap1 or full sap1 as may be most advantageous4 ,in some cases1 however1 it is constructed by enlarging the line of shelter trenches already made by the outposts4 ,to cover the working parties while excavating the trench1 when the parallel is near enough the work to be endangered by a sortie1 the outposts are advanced to about #cjj yards in front of the line1 the pickets and supports are posted respectively at about #ajj and #bjj yards in their rear1 and are covered by rifle pits and trenches made for this purpose during the preceding nights4 ,to conceal from the defence1 if possible1 the proposed location of the parallel1 these trenches and pits are constructed by all the outposts in front of their positions4 ,the reserves are held #hjj to #ajjj yards in rear of the flanks1 and the whole covering force should be equal to #a_/b or #b_/h the garrison of the place if an active defence is looked for4 ,at daylight the trenches will be far enough advanced to protect the covering force which will occupy them4 ,this force is from this time known as the 8guard of the trenches10 and is relieved usually every #bd hours1 the time of relief being so chosen as not to interfere with the working parties4 ,the working parties are1 as previously indicated1 divided into reliefs of #d or #h hours4 ,for continuous work the besieging force should be large enough to allow each man1 after being one day in the guard of the trenches and one day in the working party1 to have one day in camp4 #ha4 ,the ,second ,artillery ,position4--,by the second artillery position previously referred to is meant the position occupied by the guns of the attack1 placed in batteries1 accurately located for breaching1 enfilading1 counter-battering or other specific duty4 ,these batteries are usually of the class described under the head of 8exposed sunken batteries0 7,plates ,v1 ,,vi1 ,,vii71 and are constructed behind or in the parallels1 as explained in pars4 #dh to #ee4 ,when behind a parallel they should be1 if possible1 at least #aej yards from it in order that the blast of the guns shall not interfere too much with the occupants of the parallel4 #hb4 ,counter-batteries1 designed to dismount guns or destroy embrasures of earth or masonry at ranges from #gjj to #ajjj yards by direct fire may well be armed with #d or #e inch rifles1 since their projectiles have sufficient energy for the desired result1 and the guns admit of a more rapid and long-continued fire than do those of greater calibre4 ,the batteries must be so placed as to look through the embrasure attacked1 and the number of guns pitted against any battery must considerably exceed that in the battery4 ,counter-batteries designed to silence by direct fire guns in turrets or behind shields must be armed with guns of large calibre1 mounted with the best available cover1 and must be aided by rapid fire guns of moderate calibre1 designed to disable the turret guns either by embrasure shots or by oblique shots penetrating the parts which project from the turret4 #hc4 ,enfilading batteries act in conjunction with counter-batteries or independently2 they are designed to take the faces in flank or slightly in reverse1 but are of necessity at times limited to a slant fire4 ,they are located as nearly as possible in the prolongation of the terre-pleins4 ,when the salients are obtuse these prolongations lie near the adjacent faces for some distance1 and consequently the only possible emplacements of enfilading batteries will give ranges which may vary from #ajjj to #djjj yards4 ,they are armed with cannon of sufficiently large calibre to make their projectiles efficient even at moderate velocities1 and1 when the faces enfiladed are well provided with traverses1 the charges are reduced so as to give to the projectiles a large angle of fall4 ,when the batteries are on commanding heights higher velocities may be used4 #hd4 ,breaching batteries1 except those established on the crest of the counterscarp1 can only breach the walls of modern forts by 8curved0 or 8indirect0 fire4 ,to obtain the necessary angle of fall with the requisite accuracy and energy of blow1 the guns must be of considerable size and placed at comparatively long range2 the projectile must graze the crest of the glacis and strike the scarp wall at an angle not too oblique4 ,experience seems to indicate that the best effects are obtained1 all things considered1 when the vertical plane of fire makes an angle of from #ee to #fj with the face of the scarp wall4 ,the distance of the battery from the wall to be breached is usually from #ajjj to #aejj yards4 ,the same considerations govern the construction and armament of batteries designed to destroy rduits1 barracks1 gorge walls1 city gates1 magazines1 depots1 bridges1 locks1 etc41 etc4 #he4 ,batteries of rifled mortars or of howitzers for vertical fire should be so located1 when possible1 that the longest dimension of the target will be in the direction of their fire4 ,the effect of their projectiles is greatest when they can be fired at elevations1 of #fj to #gj and with large charges4 ,these considerations1 combined with those of good cover and easy supply1 will govern their location4 #hf4 ,opening and conduct of fire from ,second ,artillery position4--,the batteries which are ready on the morning of the completion of the parallel open fire simultaneously upon the work1 and are supported by those of the first artillery position still armed4 ,the same rules govern the fire of the first and of the second artillery position4 ,when the defence combines a number of batteries to silence one of the attack a heavy fire is concentrated upon these batteries by those from which the fire has been diverted4 ,new batteries unmasked by the defence1 or established in intermediate or other works1 should receive prompt attention from the attack1 with a view to silencing them if possible before they correct their ranges4 ,it is of the first importance that the superiority of the artillery fire of the attack shall be established at the opening of fire from the first artillery position and be maintained throughout1 and that the defence shall be prevented from repairing any batteries which have been silenced4 ,to this end a few guns will keep up a slow fire upon these batteries so long as it may be necessary4 ,every gun of the defence must1 if possible1 be kept under a heavy fire1 and the fire upon the enceinte must be opened at the earliest possible date and continued day and night1 as previously described4 #hg4 ,musketry fire will be opened as soon as a parallel is established at such distance as to make it effective2 and this may be1 for a well-regulated fire of sharpshooters1 at ranges of #abjj to #aejj yards1 or in some cases even greater4 #hh4 ,the ,advance from the ,first ,parallel4--,it is assumed that the fire from the first and second artillery positions will silence almost completely the artillery fire of the work upon the fronts attacked2 but the defence will still be able to develop when necessary a strong musketry fire1 aided at times by machine and rapid-fire or even some field guns4 ,consequently1 the advance from the parallel must be under cover4 ,approaches are1 therefore1 broken out from the parallel and pushed forward towards the work1 the workmen being protected by the fire of the guards of the trenches4 ,usually at least three lines of approaches are constructed1 concentrating upon the point of attack and following generally the lines of the capitals of the adjacent salients4 ,when attacking a line of detached works two or more lines of approaches may be constructed towards each work attacked4 ,the approaches are run in zigzags1 each branch so directed as to pass a short distance 7#cj or #dj yards7 outside the most advanced work of the defence from which it could be enfiladed2 at each change of direction of the zigzags a return of #aj or #bj yards is made to cover the approach in rear 7,pl4 ,,viii1 ,figs4 #hj and #ha74 ,the length of the branches is so regulated as not to mask too much of the front of the parallel2 they consequently grow shorter as they approach the work and vary ordinarily between #bjj and #ej yards1 seldom exceeding #ajj yards when near the work4 ,the heads of the different approaches are advanced at about equal speed so as to afford mutual support4 #hi4 ,the ,second ,parallel4--,the second parallel is located nearer to the first parallel than to the covered way1 sometimes very much nearer4 ,it is constructed and occupied by the guard of the trenches4 ,the principle followed is that the guards of the trenches shall always be nearer to the head of the sap than is the enemy in his most advanced place of arms2 so that1 in case of a sortie1 the advantage will lie with the besieger4 ,the flanks of the second parallel are refused and strengthened like those of the first1 or are even carried back to the first parallel1 to guard them against flank attacks4 ,the second parallel having been completed and occupied1 serves as a base for further advance1 which is conducted according to the same methods1 8demi-parallels0 7,pl4 ,,viii1 ,fig4 #ha7 being run out to the right and left of the approaches when they are well advanced beyond the second parallel4 ,these demi-parallels are sometimes joined1 forming a third parallel1 from which the approaches are advanced as before1 with additional parallels when needed1 until the foot of the glacis or exterior of the counter-mines is reached4 ,the number of parallels is determined by the distance at which the first is established and the vigor of the defence2 formerly three were considered all that were needed1 and this number was used at ,strasburg1 #ahgj4 ,at other modern sieges a larger number has frequently been required4 ,at ,belfort 7#ahgj-ga7 the third parallel was established at #abjj yards from the place4 ,five parallels were used at the siege of ,fort ,wagner 7,july-,september1 #ahfc74 ,the approaches are driven in zigzags by simple trench1 flying or full sap1 until the direct advance becomes equal to about one third of the length of trench2 and from this point they are driven directly upon the work by double-traversed sap 7,pl4 ,,iii1 ,figs4 #bh-ce71 the latter being1 as a rule1 used only in advancing from the foot of the glacis1 or during the third period of the siege4 ,,third ,,period4 #ij4 ,the ,third ,period of the ,siege frequently called the 8close attack10 includes all the steps between establishing the last parallel and the surrender of the place4 ,these are the capture and crowning of the covered way1 breaching the scarps and counter-scarps1 passing the ditch1 capturing and crowning the breaches of the outworks and main works in succession1 and the final reduction of the interior retrenchments1 or keep4 ,all these operations are carried on within close and deadly range of small arms and shells of ,coehorn mortars1 and many of them within range of hand grenades and upon ground honeycombed with mines and countermines1 or liable to be flooded or inundated4 ,they are slow in progress1 uncertain in results1 and require an extravagant expenditure of men and material4 ,they can be pushed to a successful issue only when the artillery fire of the place is silenced and its small-arm fire is almost completely kept down by the fire of the attack4 ,the conditions of modern warfare are such1 however1 that by the time the attack has reached the foot of the glacis the losses and exhaustion of the garrison are frequently so great as to preclude an obstinate1 close defence2 and1 in the majority of cases1 the place is compelled to surrender before the close attack is commenced4 #ia4 ,the capture and crowning of the covered way is accomplished by assault or by sap4 ,the former is an extremely hazardous and bloody operation1 which all authorities unite in condemning1 and which should be undertaken only in extreme cases4 ,it is carried out usually at night1 by forming an assaulting party in the parallel1 who rush forward to the crest of the covered way2 capture1 if possible1 its guards1 and under any attainable cover open a fire upon the crest of the work4 ,all available small-arm and machine-gun fire combines with this to keep down the fire of the defence2 and under cover of this fire the working parties construct1 by flying sap1 a trench crowning the covered way1 and the communications between it and the parallel4 ,the trench is occupied as soon as it affords cover1 and is subsequently completed and prepared for the reception of its guns and infantry guard4 ,in crowning the covered way by sap 7,pl4 ,,iv1 ,fig4 #cf71 the saps are broken out from the parallel1 a circular place of arms is constructed1 which gives additional communication and serves as a depot for trench materials1 the traversed sap is pushed forward1 and the covered way crowned as previously described 7par4 #cf74 ,it will frequently be necessary to run out at right angles to this sap short branches of parallels 7,pl4 ,,ix1 ,fig4 #hc71 to serve as places of arms1 or as trenches of departure for mines or galleries1 for underground warfare or for breaching walls4 #ib4 ,breaching the ,scarps and ,counter-scarps4--,the counter-scarp1 as a rule1 and the scarp at times is breached by mining4 7,see ,military ,mining1 pars4 #ia-ic74 ,when practicable1 however1 the scarp is breached with artillery and preferably by guns of the second artillery position2 since a breaching battery on the crowning of the covered way1 which must be provided with most ample splinter-proofs to protect the gunners from flying splinters of masonry and shot1 is in general constructed only with great losses and delays2 and the guns in this position must be fired under great angles of depression1 requiring very deep embrasures to avoid exposing the cannoneers4 ,when the ditch is deep and narrow it may be necessary to blow down the counter scarp and part of the glacis1 in order to expose the scarp-wall to the fire of the breaching battery1 whether on the glacis or at a distance4 ,this necessity should be foreseen and provided for in locating the batteries4 ,a full or semi-detached scarp-wall will be breached when the battery is on the glacis by making vertical cuts at the ends1 and a horizontal cut at about one third or one fourth its height from the bottom1 and then firing shells into the part to be brought down1 continuing the fire until the large masses of masonry are broken up1 and the slope is made gentle and smooth enough to admit of easy ascent4 ,a detached scarp-wall will be breached by a glacis battery1 or any scarp-wall by a distant battery1 by continued battering1 which will not only knock down the wall1 but also break up the fragments and make a practicable ramp4 #ic4 ,the ,capture and ,crowning of the ,breach4--,the decision as to whether the breach shall be captured and crowned by assault or by sap will be governed by considerations similar to those which determined the character of the attack upon the covered way4 ,the difficulties and dangers of the assault are perhaps greater than in that case4 ,the assault1 if undertaken1 will be carried out in a similar manner1 previous preparations having been made by making a practicable breach at least #be to #cj yards wide1 a practicable descent into the ditch of equal width1 and a covered place of assembly for the working party and a depot of trench materials in immediate proximity to the breach4 ,the artillery defence of the ditch1 whether from caponires1 flank embrasures or casemates1 or from adjacent works1 must of course be silenced before crossing the ditch either by assault or by regular approach4 ,this is accomplished by counter-batteries on the glacis1 by heavy field guns located in temporary batteries in the trenches1 by mines1 or by overhead or indirect fire from the distant batteries1 or from light mortars in the advanced trenches1 as may be necessary4 ,if the interior arrangement of the work is known by the besieger the assault maybe made by night2 but if it is unknown1 the confusion resulting from a night attack will be so great as to render its success almost hopeless1 and the assault will have to be delivered by day4 ,the assaulting columns will be made up of an advanced line of skirmishers 7selected men1 good shots1 and generally volunteers71 followed by a working party of sappers to clear away obstacles1 these closely followed by the columns of assault2 while the supports and reserves move forward in the trenches to join in the assault as circumstances require4 ,the troops who first gain the crest establish themselves there and hold the breach until those coming after them pass and engage the garrison1 while some detachments strive to capture and open one gate or more to admit the reserves4 ,the assaulting force should be equal at least to once and a half or twice the garrison1 and simultaneous attacks should be made upon other breaches or accessible parts of the work to divide the attention of the defence4 ,these false attacks are sometimes successful1 and preparations for taking advantage of this contingency should not be omitted4 ,the subdivisions of the assaulting force should each receive explicit instructions as to its special object1 and under no circumstances should their lines of march intersect4 ,unmistakable signals of recognition should be prescribed to prevent conflicts arising between the different parties meeting within the work4 ,the bombardment preceding the attack should not cease1 and thus notify the defence when the assault is to be made2 but the guns should be directed upon adjacent parts of the work until the assault penetrates the work or is repulsed4 #id4 ,in the attack by the sap the method of crossing the ditch adapted to the circumstances is used 7pars4 #ci-da1 ,pl4 ,,iv1 ,figs4 #cg-da7 and the sap is started at the foot of the breach1 driven up it1 and the breach is crowned according to the methods previously described 7par4 #cf74 ,the sappers are protected from small sorties by the fire from the crowning of the covered way and any other points bearing on the head of the sap4 ,fireballs1 electric lights and other means will be used during the night to light up the parapets of the work and expose the defenders1 in this as in the previous operations of the siege4 ,the crowning of the breach will be extended and converted into a place of arms1 from which further sapping can be carried on in a similar manner1 until the breach in the last retrenchment is crowned and the preparations for the final attack upon the garrison are made1 or the place surrenders4 ,if the garrison takes refuge in an interior keep and continues the defence the keep must be reduced by similar methods4 #ie4 ,additional ,operations in the ,attack of an ,intrenched ,camp4--,the operations above described are those necessary to reduce a fortified place of the older type1 or a detached work of an intrenched camp4 ,the latter1 though of less extent and with a smaller garrison1 offers as a rule greater resisting power1 since it is usually subject to front fire only1 has more complete bomb-proof cover1 and is free from the presence of non-combatants4 ,while a great advantage is gained by the capture of two or more of the advanced forts1 the resisting power of the intrenched camp is by no means destroyed4 ,these forts are subject to the fire of the collateral works1 of which frequently two or more must be silenced before a further advance can be made4 ,the beleaguered army may still be in condition to recapture the forts by vigorous assaults2 and in almost every case1 before the fall of the works of the outer line1 a line of provisional fortifications of high resisting power1 connected by trenches1 will have been constructed by the defence in rear of the captured works1 with its flanks secured by the collateral works of the outer line4 ,an assault against works of this class offers no prospect of success4 ,the besieger is therefore obliged1 as soon as he captures a detached fort1 to put it in condition to withstand the assaults of the besieged army and to afford protection from the artillery fire of the collateral works1 and then to push forward his approaches against the successive positions prepared by the defence1 which will as a rule present a front equal to or greater than that which can be occupied by the attack4 ,the gorges of the captured works are repaired and strengthened1 covered communications are made through the faces1 either through the breaches or in more convenient points1 traverses are repaired or built to protect against the fire of the collateral works1 and the captured works are connected by trenches which afford emplacements for batteries and form a new parallel from which the saps can be driven in attacking the intermediate works4 ,simultaneously with this attack1 it is usually advisable to advance from the flanks of the first or second parallel upon the forts of the outer line which form the flanks of the intermediate line4 ,the approaches can generally be driven with comparative ease owing to these works having already been partly disabled and now being subject to a flank and reverse fire from the newly-established batteries4 ,the flanks of the intermediate line being turned by the capture of these works1 a portion or the whole of it will of necessity be abandoned4 ,the subsequent operations up to the capture of the enceinte will be of the same nature as those already described4 #if4 ,occupation of a ,conquered ,place4--,immediately upon the fall of the place it must be occupied by a force 7chosen when possible from the reserve which has not participated in the final assault7 sufficient to control not only the inhabitants1 but also the disorderly soldiers of the attacking force4 ,all pillaging1 wanton destruction1 and abuse of the conquered must be restrained with a strong hand1 immediate and exemplary punishment being inflicted upon offenders4 ,the orderly portion of the defenders must be protected1 and such steps taken for supplying their needs as humanity requires2 while the disorderly ones must be repressed with such severity as may be necessary4 ,so soon as order is established a careful inventory of captured property is made1 and it is stored subject to the orders of the government4 ,when the possibility exists of the place being attacked or besieged by the enemy1 all its resources which are available for defence are collected1 repaired1 and stored for use4 ,,vauban',s ,,maxims4 #ig4 ,marshal ,vauban1 the great ,french military engineer 7born #afcc1 died #agjg71 whose experience and success in sieges made him the great authority on the subject1 formulated certain maxims for governing the conduct of a siege1 the observance of which led to almost certain success1 and the departure from them almost invariably resulted disastrously4 ,the most of these are as applicable to sieges of to-day as they were to those of his own time4 ,the following#f bear upon the second and third periods of the attack3 #ast4 ,to delay the opening of the trenches until the besieging forces are all well posted and made secure by fortifications from an attack either from the garrison or from a succoring force2 and until everything requisite for carrying on the work vigorously has been collected and is ready at hand when wanted4 #b;d4 ,to make a single attack rather than a double one1 unless the two attacks can be well connected and the besieging force exceeds considerably in strength the garrison4 ,this1 as a matter of course1 excludes false attacks1 and double separate attacks1 unless the superiority of the besieging force is very great4 ,by a single attack is understood one by which it is proposed to gain possession of the main work by a single breach at some point2 by a double attack it is proposed to effect two breaches of the main work4 ,the advantage of the latter lies in forcing the garrison to divide their strength for the defence of the two breaches1 whilst the assailing forces1 being under one leadership1 can at any moment concentrate if necessary upon the point most favorable to their assault4 #c;d4 ,to embrace within the parallels and approaches all the defences which bear upon the site to be occupied by the besieger's works1 in order to have secure positions for establishing the batteries that may be required to silence the fire of these defences4 #dth4 ,to multiply the approaches1 with the view of giving mutual support1 less encumbered communications1 and dividing the fire of the defences1 which1 if concentrated upon a single one1 might soon destroy it4 #eth4 ,to throw up at least three main lines of parallels1 placing them in the best positions for mutual support and for guarding the approaches and batteries from sorties of the besieged4 #fth4 ,to avoid attacking a point upon which the approaches can be run only on a narrow front1 or one which can only be approached over marshy ground1 or on causeways4 #gth4 ,to be careful not to push forward any portion of the trenches until they are well flanked and protected by trenches in their rear1 which are completed and occupied by troops4 #hth4 ,to avoid encumbering the approaches with trench materials1 tools1 workmen1 or troops2 placing all of these in the parallels1 on the right and left of the approaches1 so as to be ready at hand when wanted1 and to be rapidly sent forward through the trenches of the approaches1 which should be kept free for this purpose4 #ith4 ,to place the ricochet 7enfilading7 batteries in such positions that they can have an enfilading and slant reverse fire upon the guns of the defences to be attained by them4 #ajth4 ,to refrain from opening fire from any series of batteries until it can be done at the same moment from all of them4 ,in connection with this and other siege operations1 ,vauban remarks that precipitation in sieges does not hasten the close of them1 but often prolongs them and renders them more bloody4 #aath4 ,to employ the fire of the batteries and trenches1 rather than open assaults1 to drive the besieged from their defences1 before attempting to occupy them by the besieging force4 #abth4 ,when it is decided to make an open assault1 to do so by day1 if there is no portion of the fire of the defences which bears upon the point to be carried that is not completely kept under by the fire of the batteries and trenches2 but1 in the contrary case1 when the fire of the defences is not completely kept under1 to make a night assault4 #acth4 ,not to attempt an obstinate resistance to an open assault of the besieged upon any unfinished portion of the trenches2 but rather to withdraw the workmen and the few troops near them to some point behind the parallel immediately in rear1 and then to open a vigorous fire from it upon the assailing force4 #adth4 ,to keep within the cover of the parallel when the assailant is advancing to the assault1 and leave him to expose himself to its fire as long as he pleases1 and then1 when he is well cut up1 and has got thrown into confusion1 as he necessarily will at night1 in the trenches that he may have carried1 to fall upon him with the bayonet and drive him out4 #aeth4 ,not to push such charges too far from the parallel1 but to retire promptly1 so soon as the assailant has fairly taken to flight1 within the cover of the parallel1 so as not to draw the fire of the besieged works4 ,,journal ,,of ,,the ,,attack4 #ih4 ,in connection with the plan of attack previously referred to 7par4 #gh71 a complete ,journal of the ,attack will be kept in which will be recorded day by day a detailed record of the daily progress of the siege1 giving the day and hour of starting and completing each battery1 parallel1 approach1 etc41 with their daily progress1 dates of opening fire from each battery1 and1 generally1 every incident connected with the siege4 ,this journal will be supplemented by journals kept by the chiefs of engineers and artillery1 in which will be consolidated the daily reports of all subordinate commanders of these respective arms1 giving the expenditure of ammunition1 the performance of the guns1 carriages1 etc42 the modification made in details of parapets1 batteries1 magazines1 etc41 with their value2 the results of trials of new devices1 and special reports upon any points connected with the siege4 ,these journals will be carefully preserved and copies transmitted to the ,war ,department from time to time for future use4 ,,chapter ,,vi4 ,,the ,,defence4 #ii4 ,preliminary ,considerations4--,the defence of a fortified place is entrusted to a commanding officer1 who1 when the siege is established1 is generally known as the 8,governor of the ,place40 ,his duties become more exacting and his powers more absolute from the beginning of hostilities until the place is invested and cut off from communication with the exterior1 when1 since the whole responsibility of the defence rests upon him1 his powers over both the garrison and the inhabitants of the place1 of necessity become autocratic in all matters affecting the defence1 directly or indirectly4 ,he1 of course1 avails himself of the counsel and advice of his subordinate officers and may make up a 8,council of ,defence0 from his second in command and the commander of the engineers and of the artillery2 but the ultimate decision of all questions must rest with him alone4 ,during peace and after the beginning of hostilities up to the near approach of the investing force1 the civil authorities retain their ordinary jurisdiction1 unless martial law is declared by proper authority2 but after the place is invested1 martial law 7or state of siege7 exists from necessity1 and the police power1 the control of provisions and supplies of all kinds1 public and private1 buildings1 animals1 vehicles1 etc41 and everything necessary for the defence of the place fall into the hands of the governor1 who also is empowered to direct who shall be sent out and who shall be retained within the place1 and what necessary service or labor shall be performed by the inhabitants4 ,having been selected for these onerous and exacting duties1 he1 under no circumstances1 allows himself to be cut off from his post1 and is therefore debarred from leading his troops in person in the active operations outside the work or exposing himself unnecessarily or recklessly during any period of the siege4 #ajj4 ,the ,garrison4--,the garrison should consist of artillery and infantry1 and1 in an intrenched camp1 of enough mounted troops for escort1 messenger1 and a limited vedette service4 ,the strength of the infantry is generally regulated so as to give a suitable garrison to each detached work1 and about #a to #b men for each yard of the front of attack4 ,the artillery is allowed about #ab men for each gun4 ,the number of engineers is determined for each place by the probable amount of engineer work that will be required4 ,these troops make up about one-third of the entire force4 ,a general reserve of all arms 7principally1 however1 foot troops7 makes up the other two-thirds1 and is held as 8a fighting force0 for preventing the investment of the place1 or for breaking up the investing lines when established4 ,this reserve is called upon for work on the front of attack or in the trenches only when it cannot be avoided4 ,in smaller places the portion of the garrison called upon for the outer line of defence may be increased to one-half or two-thirds1 and the general reserve be reduced to one-half or one-third of the entire force4 ,when the investment is strongly established the general reserve will usually be combined with the other troops4 ,the troops engaged on the front of attack are usually assigned to the different sectors of attack and are divided into reliefs 7ordinarily three71 each relief having as a rule a tour of one day in the front lines1 one in the immediate supports1 and one in the reserve and in interior fatigue duty4 ,the ,governor1 however1 so regulates the details as to impose upon the troops the least work consistent with an energetic defence4 #aja4 ,armament4--,the guns for arming the place should be placed in position or in store within the works before the beginning of hostilities4 ,there should be mounted in commanding positions a sufficient number of high-power guns to hold the enemy's first works at a distance and to fire upon his camps1 etc41 if placed too near4 ,in addition to these1 a full supply of light guns1 including machine and rapid-fire guns1 should be at all times equipped and supplied for immediate use in meeting an assault or surprise4 ,their emplacements1 platforms1 etc41 should be in readiness for use at any moment4 ,in large places and for an active defence there will be needed also enough field-guns to properly equip the general reserve 7about #d guns per #ajjj men74 ,these should be considered a part of the equipment of the reserve4 ,it being1 from economical considerations1 impossible to supply guns to fully arm all the fronts of a place1 enough only are usually provided to thoroughly equip the sector of attack and to replace those disabled4 ,these are stored within the place where they are secure against deterioration or injury1 and are mounted in the sector of attack when it is definitely determined4 ,the numbers of high-powered guns1 howitzers1 mortars1 and machine and rapid-fire guns needed must be determined from the size of the place1 its garrison1 and the character of attack which may be expected4 #ajb4 ,ammunition1 ,provisions and ,supplies4--,a plentiful supply of ammunition1 especially of projectiles1 for all the guns should be kept constantly on hand4 ,the projectiles1 which may be stored for an indefinite term without deterioration1 may be distributed in magazines in proximity to their batteries2 the powder should be so stored as to preserve its properties1 and be distributed to the service magazines at such times and in such quantities as may be necessary4 ,other equipments will be stored and handled in accordance with the same principles4 ,the utmost care will be taken in storing and issuing the provisions and supplies belonging to the troops2 and in cases of necessity during the siege the sales of provisions to the inhabitants by the dealers will be regulated1 both in prices and quantities1 by the military governor4 #ajc4 ,sanitation and ,hygiene4--,the most rigid sanitary measures and rules of hygiene should be enforced from the beginning of the siege1 under the direction of the military governor1 whose medical officers should join with the health officers of the place 7if any exist7 in guarding not only the troops but all the inhabitants from all avoidable causes of epidemic diseases4 ,extreme rigor in carrying out these regulations in not only allowable1 but is most urgently required4 #ajd4 ,preparations for ,defence4--,an active defence being presupposed1 all possible measures for its execution should be taken before the near approach of the enemy interferes with them4 ,the principal ones are as follows1 viz43 ,advanced posts are established as far from the work as is prudent1 say #cejj to #djjj yards1 placed at points which may be easily defended or which would be advantageous positions for the enemy's batteries1 etc4 ,these1 when possible1 should be so placed that the ground between them is swept by their infantry fire and by the artillery of the place4 ,they should be provided with good cover for the troops1 and parapets for infantry and field-guns4 ,when not naturally strong1 field-works should be built4 ,quarries1 ditches1 sunken roads1 villages1 woods1 etc41 should be taken advantage of1 either as points of defence1 passive obstacles1 or covers for communications1 as may be best4 ,lines of retreat to the work as secure as possible from hostile fire should be provided4 ,all supplies in the vicinity of the work which will be useful during the siege should be collected and taken into the place4 ,means of communicating with the exterior by telegraph1 telephone1 signal flags1 lanterns and heliotropes1 carrier-pigeons and balloons1 should be secured4 ,search-lights for illuminating the exterior should be obtained1 and as soon as practicable bomb-proofs and shelters for the inhabitants should be prepared in the body of the place2 and in connection with the civil authorities the fire department of the place should be organized and taught how to extinguish fires with dry earth and by pulling down buildings when water is not available4 ,the service of security and information should be extended to the furthest possible limit1 not only by outposts1 etc41 but by telegraph operators and reliable correspondents at long distances from the place2 and preparations should be made to retard the approach of the enemy by the destruction of the roads1 bridges1 etc4 #aje4 ,defence during the ,first ,period of the ,siege4--,upon the approach of the enemy each work should receive its permanent garrison1 and the fighting reserve should go out to occupy the advanced posts and to take full advantage of its interior lines to hold him back and punish any careless or ill-advised advance1 being aided in this when possible by the fire of the heavy guns of the place4 ,care must be taken to avoid too great dispersion of the troops1 and exposing advanced parties to being cut off and captured by pushing them too far to the front or holding their positions too long2 but no opportunity should be missed of attacking and destroying or beating back hostile detachments when tactical conditions warrant it4 ,the defence during the first part of this period differs but little from the ordinary defence of an intrenched battle-field4 ,the principal differences arise from the fact that the flanks of the advanced lines and the lines of retreat to the work are so well covered that with ordinary precautions they may be considered secure1 and all energies may be directed to meeting the front attack and executing offensive returns4 ,so soon as the point of attack selected by the enemy becomes known the advanced positions may be more fully manned and equipped2 trenches with inconspicuous parapets1 or preferably without any1 may be made to cover the infantry1 field-guns1 and sometimes siege-guns on travelling carriages4 ,these positions may be1 as previously stated1 #bejj to #cjjj yards from the permanent works1 and the intervals between them may be swept by the heavy guns of the latter4 ,if these positions can be so strongly held as to compel the besieger to attack them with his heavy guns1 he will be compelled to establish his first artillery position at a very great distance--possibly #ejjj to #fjjj yards from the work4 ,at ,belfort1 #ahgj1 positions of this kind were taken only after seventy-seven days of siege4 ,as the advanced positions may be subject to the fire of the heaviest class of siege-guns1 if any parapet is made it should be of the nature of a glacis of gentle slope and little command4 ,infantry trenches should be made narrow and deep as a protection against shells and shrapnel 7,pl4 ,,ix1 ,fig4 #hd71 and gun-emplacements should be as small as practicable and almost entirely in excavation1 for the same reason4 ,positions so prepared suffer very little from gun-fire1 and will frequently require attack by systematic approaches4 ,an efficient outpost service must be maintained in front of these positions to prevent their being taken by surprise4 ,when but a limited number of troops are available for defence it is of course impossible to push out the advanced posts so far to the front4 ,in all cases1 however1 they should be placed at the greatest practicable distance4 #ajf4 ,opening of ,artillery-fire by the ,defence4--,the artillery-fire of the defence should be opened upon the besieger's batteries1 etc41 before they are ready for action1 so that the ranges may be obtained and the tables of fire corrected without interference by the hostile fire4 ,if this can be accomplished1 the increased effect due to the accurate fire of the defence may more than counterbalance the numerical superiority of the attack1 and result in preventing the completion of some of his batteries and in silencing others4 ,if1 on the other hand1 the attack anticipates the defence in obtaining the range1 his superiority in numbers and accuracy will frequently necessitate abandoning some emplacements and mounting the guns in others1 where they may be used in the later stages of the siege4 #ajg4 ,defence during the ,bombardment and ,assault4--,the amount of ammunition which can be profitably expended by the defence during the bombardment must be determined by the quantity on hand and the advisability of exposing by their fire the positions of the guns4 ,the infantry troops and the light guns are held under cover1 ready to be moved forward to meet the assault if made4 ,special care will be taken to avoid being deceived by false attacks2 and the assault1 if made1 will be met as previously described 7par4 #f74 ,if the attack is repulsed1 an offensive return may be made by the general reserve1 assisted1 when necessary1 by the local reserves of the front of attack2 but the garrisons of the permanent works should not be withdrawn from them for this purpose1 as it is always possible that they may be needed to protect the works and cover a retreat4 ,if the assault succeeds1 the defenders will retire to their positions in rear1 from which the strongest possible fire will be directed upon the pursuing troops and upon the captured position to render its possession difficult or impossible4 ,if the assailants are driven off1 the position is immediately reoccupied by the defence4 #ajh4 ,defence during the ,second ,period of the ,siege4--,the point of attack having been definitely determined by the preliminary steps of the attack in opening the parallels and establishing the batteries1 the besieged will at once proceed to mount extra guns and reinforce the troops upon the threatened fronts4 ,he will keep his outposts or sentinels during this and the subsequent periods as far to the front as possible1 to prevent surprises and to keep out reconnoitring parties spies1 etc41 etc4 ,from observations previously established1 he will locate at the earliest possible moment the batteries1 etc41 of the attack1 and will prevent their completion and arming by the use of shells and case-shot charged with high explosives1 fired from howitzers and mortars4 ,he will use his long guns for counter-battering those of the besieger1 and generally for direct fire upon exposed targets4 ,by taking the initiative he may frequently obtain the upper hand in the artillery duel1 and possibly be able to prepare the way for strong sorties1 and the destruction of the besieger's works4 ,in any case he must at this stage develop the full fire of his guns and work them to their maximum value4 ,if1 however1 the superiority of the artillery of the attack is pronounced1 and it becomes impracticable to serve any battery advantageously1 it will be better to dismount its guns and remount them in other positions1 as indicated in the preceding paragraph 7par4 #ajf74 ,all efforts will be made to prevent the construction of the parallels and approaches1 their positions being discovered by the use of the search and other lights1 and the work upon them retarded by direct and curved fire4 ,for the latter light rifled mortars promise to be very effective4#g ,the trenches connecting the detached and intermediate works will be strengthened1 and counter-approaches will when practicable be driven out to afford positions for enfilading the approaches4 ,the field and machine guns will be held in constant readiness for use1 and will be brought into action at every favorable opportunity2 but will be withdrawn and placed under cover previously prepared so soon as the fire upon them becomes too severe to be endured4 ,meanwhile a new position in rear1 with its flanks supported upon the adjacent detached works1 will be selected and made ready for defence in case the front line is taken4 ,the general reserve will be used for offensive movements1 which are made whenever favorable opportunities arise1 particularly in making counter-attacks after unsuccessful assaults4 #aji4 ,defence during the ,third ,period4--,the defence of the detached works of an intrenched camp during the ,third ,period will be conducted1 so far as the general reserve is concerned1 in very much the same manner as during the ,second ,period2 but in the immediate defence of the detached work itself1 owing to the close approach of the besieger1 its character will change4 ,the artillery except the field and machine guns will be silenced1 and the latter will usually be only available for defending the ditches and for repelling assaults4 ,light guns will1 however1 be held in readiness for temporary use when practicable4 ,the outposts will of necessity be drawn in and replaced by a chain of sentinels along the parapets of the covered way or the main parapet1 who will pick off the besiegers at every possible chance1 and will be reinforced by the rest of the garrison when an assault is imminent4 ,all flanking defences will be kept in as good condition as possible1 and in readiness to prevent the crossing of the ditch1 or to repulse an assault4 ,grenades and shells will be kept in readiness to roll into the ditch1 the breaches will be obstructed and mined if practicable1 counter-mines will be brought into play1 and all other possible measures taken to retard the approach of the besieger to the breach and to repel his assaults4 ,when1 however1 the work is reduced to such a state as to make its defence hopeless1 it should not be held at the expense of great losses to the defence1 unless the besieger's works can be considerably delayed by doing so4 ,when the position consists of an enceinte with ordinary outworks1 the investment during the ,third ,period of the siege will be closer1 the opportunities for using the general reserve will usually disappear1 and its troops will be merged with those of the general defence4 ,when1 in this case1 the place is to be defended to the last1 all measures will be taken for the defence of the breach2 and after this is carried1 for the final defence of the inner retrenchments or keeps4 ,the tactical handling of the garrison for this purpose is in accordance with the principles already laid down 7par4 #f1 and ,art of ,war1 pars4 #bhb-hd47 ,the sorties recommended during a siege are1 when made by the general reserve and in large bodies1 usually carried out by moving the troops from the collateral works upon the flanks of the besieger's works4 ,in the close attack1 however1 they may be made by small parties moving to the front from the nearest outpost or salient4 ,the object in all cases is the same--to destroy the enemy's works1 delay his advance1 and inflict upon him all possible loss4 ,,the ,,capitulation4 #aaj4 ,should the defensive policy of the state not require a place to be held to extremity1 the governor must be fully informed of the fact1 and the extent of the defence and the conditions of capitulation must be fully understood by him before the investment4 ,as a rule1 however1 no excuse will be received for the surrender of a place until every means of defence is exhausted1 and further resistance is not only hopeless1 but impossible1 the only rule which can guide the governor being that 8one additional day of defence may be of incalculable benefit to his country40 ,the old rule1 copied from the ,french1 but no longer observed by them1 requires the defence to sustain at least one assault on a practicable breach in the body of the place4 ,within recent years1 in civilized warfare1 no cases have occurred in which such assaults have been made1 the places having been reduced by the more distant attack2 but assuming such an assault to be repulsed1 it will not justify the surrender of the place so long as a possibility of repulsing similar assaults exists4 ,the garrison must withstand all attacks of whatever nature to the last extremity1 and continue the defence up to the full requirements of duty and honor--surrendering only when nothing else is possible4 ,,journal ,,of ,,the ,,defence4 #aaa4 ,a ,journal of the ,defence1 entirely similar to that of the attack1 will be kept by the besieged for use by the ,war ,department in case of a successful defence4 ,nothing should be entered in the journal which might be of special value to the besieger in case the place is taken1 but a separate journal of such matter should be kept in cipher1 or should be destroyed before the surrender of the place4 ,,chapter ,,vii4 ,,parks ,,and ,,depots1 ,,shelters ,,and ,,huts1 ,,kitchens1 ,,ovens1 ,,sinks1 ,,latrines1 ,,water-,,supply1 ,,etc4 ,,parks ,,and ,,depots4 #aab4 ,the ,engineer and ,artillery ,parks and ,depots are located and arranged for security against the artillery-fire and the attack1 by surprise or otherwise1 of the defence1 and also for facility in receiving1 storing1 and distributing materials and supplies4 ,the first condition is fulfilled by placing them at a safe distance1 concealing them from the view of the defence if possible1 and guarding them against attack1 and the access of incendiaries1 etc41 by strict application of ordinary defensive tactics1 and a most thorough system of interior guards4 ,powder depots1 trains1 etc41 especially are guarded against the access of all unauthorized persons4 ,the second condition1 when railroad communication is used1 is satisfied by making the park conform to the best-planned railroad terminals and freight-yards4 ,a type arrangement is given in ,plate ,,ix1 ,fig4 #he1 in which switches from the main line give access to as many side-tracks1 a1 b1 c1 d1 etc41 and spurs1 #a1 #b1 #c1 etc41 as may be needed4 ,when practicable1 these sidings should connect at each end with the main line in order to afford free ingress and egress from both directions4 ,they should be placed at such distances apart as to allow loading-platforms and the desired room for sheds1 piles of materials1 etc41 between them2 large areas being left for light1 and small for heavy1 materials4 ,the spurs1 #a1 #b1 #c1 etc41 should preferably be short2 but if long1 should be connected by switches4 ,a 1 as indicated1 is frequently convenient for reversing complete trains without uncoupling the cars1 and is indispensable when a turn-table is not available4 ,when the powder-depot is separated from the main park it is better to reach it by a special track branching from the main line at some distance from the park1 so that the ammunition-trains will not pass through or near the latter4 ,the sketch given is proposed as a type only1 since the park may occupy one or both sides of the main line1 be long and narrow1 short and broad1 regular or irregular in outline1 as may best conform to the ground available4 ,standard-gauge roads will1 when practicable1 be laid between the main park and the smaller depots4 ,when this is not feasible1 narrow-gauge tram-roads will be used instead1 and will also connect the smaller depots with the trenches and batteries4 ,the portable tramways used by contractors are well fitted for use in the trenches4 ,when the park is located upon navigable water a number of piers and wharves are occupied4 ,they should be provided with derricks or cranes1 and tracks and cars upon which materials may be loaded directly from the ships4 ,the park may then be arranged on the general plan above indicated4 ,the switches are so arranged as to allow empty cars to return to the wharves on a track different from that used by the loaded ones4 ,in storing materials and supplies in the park care must be taken to place each class by itself1 and to so pile them that they can be readily inventoried and inspected1 and be removed or replaced without disturbing other piles4 ,this requires the piles to be arranged in regular order1 with unobstructed passages between them1 and prohibits piling articles of different kinds or sizes on top of each other4 ,,shelters ,,and ,,huts4 #aac4 ,in a regular siege1 the besieging army will1 as a regular rule1 eventually be provided with tents or portable huts for shelter2 but before this is accomplished much suffering and consequent disease may result from exposure1 which could be avoided by the construction of temporary shelters1 huts1 and screens from materials available for this purpose4 ,in severe winter weather tents and thin wooden huts do not afford sufficient protection1 and it may be necessary to substitute for them others with walls of logs1 sods1 sand-bags1 adobe1 or other materials1 or even huts partly or entirely sunk into the earth4 ,the greatest care must be exercised in enforcing proper ventilation and cleanliness in huts of this class4 ,if this is not done serious fevers and other camp diseases are almost sure to occur4 7,art of ,war1 ,art4 #ceb-c47 ,the figures given 7,plate ,,ix1 ,figs4 #hf-id7 have been selected from a great many examples to serve as suggestions4 ,they may be modified or combined1 as circumstances require4 ,their construction is evident from the figures1 and requires no description4 ,ditches surrounding the huts are made to carry off rain-water4 ,heavy roofs are supported by poles set up inside the hut as needed4 ,fireplaces are dug in the sides of the excavation1 or are built up of sods1 clay1 etc4 ,it is better to make two1 as shown1 to obtain a good draught in any wind4 ,chimneys are made of sods or of sticks plastered with clay1 unless drain-tiles1 tin cans1 or other suitable materials can be found4 ,great care must be taken to prevent their setting the roof on fire4 ,in many cases water-proof roofing felts and papers may be obtained and used for roofs1 etc41 in huts and shelters4 ,the lumber from packing-boxes1 tin from canned vegetables1 and wire from baled forage may frequently be utilized for doors1 chimneys1 ties1 etc4 ,straw mats for mattresses1 etc41 are economical in the use of straw and conduce to cleanliness1 as they can be easily taken up and replaced4 ,the method of making them is shown in ,pl4 ,,ix1 ,fig4 #ie4 ,when twine is not at hand1 they may be woven of straw rope4 ,they1 as well as all other bedding1 should be taken out and sunned every dry day4 ,ordinary hurdles laid upon the ground or raised a few inches above it protect the blankets1 etc41 from the moisture of the earth4 ,it cannot be too strongly impressed upon officers1 that all devices of the kind above indicated1 which add to the comfort of the men1 add also to their health1 morale1 and efficiency4 ,,kitchens ,,and ,,ovens4 #aad4 ,in our service a company will usually have a camp-cooking outfit sufficient for its needs1 and generally of good pattern2 but these are not always on hand when needed1 and small detachments are frequently deprived of them for days or weeks4 ,in ordinary soil1 kitchens1 and in a clay soil ovens1 can be constructed1 which1 with a few kettles and cans1 will enable the men to prepare for themselves fairly good meals without unnecessary waste of fuel4 ,a few of these are figured in ,pls4 ,,ix1 ,x1 ,figs4 #if-ajc4 ,the banks of the trench shown in ,fig4 #if afford support for cross-bars1 and protect the fire from the wind4 ,the type shown in ,figs4 #ig1 #ajb1 #ajc take the place of a stove1 require but little fuel1 and secure a steady heat4 ,to obtain a good draught they should be so built that the wind blows toward the chimney4 ,for this purpose they may radiate from a central chimney4 7,the flues of those not in use may be temporarily stopped up with sods47 ,the arch of the oven shown in ,pl4 ,x1 ,fgs4 #ih-aja1 may be built over a piece of sheet iron if it can be obtained2 if not1 over a hurdle well smeared with clay4 ,a slow fire will1 under favorable conditions1 dry and bake the clay arch so that it will stand after the brushwood of the hurdle is burned out4 ,they may then be heated and used for baking4 ,,latrines1 ,,sinks1 ,,etc4 #aae4 ,latrines and sinks for the reception of garbage1 etc41 are objects of the greatest importance in all camps1 temporary or permanent2 and1 unless properly made and cared for1 they speedily make their presence known1 and become a most prolific source of discomfort and disease4 ,for permanent camps liable to be occupied for a long time special arrangements for the disinfection1 removal1 and destruction of garbage and excreta must be made4 ,for temporary camps it will suffice to provide pits with suitable conveniences and screens2 covering with a thin layer of the excavated earth all deposited garbage and excreta before they become offensive4 ,when1 as is sometimes the case1 these pits cannot be kept free from water1 it may be necessary to use in addition lime1 copperas1 carbolic acid1 or other chemical disinfectants and deodorizers4 ,the ordinary constructions used in temporary camps are shown in ,pl4 ,x1 ,figs4 #ajd-ajg4 ,separate latrines for officers are constructed and screened4 ,the seat shown in ,fig4 #ajg1 when one can be obtained1 adds much to their comfort4 ,in more permanent camps the latrines may be roofed and screened with canvas or boards1 and board seats be provided for the men4 ,uninclosed sinks and latrines should have earthen banks all around them1 to indicate their position and to prevent men walking into them at night4 ,upon abandoning a camp all sinks and latrines are to be disinfected and filled up4 ,,water-,,supply4 #aaf4 ,the problem of obtaining a sufficient and wholesome water-supply for a besieging army is usually one difficult of solution4 ,the precautions which are necessary in ordinary camps 7,art4 of ,war1 #ceb and #ceh7 become of still greater importance in this case1 owing to the choice of the source of supply being limited to those which are not controlled by the besieged1 and to the constantly increasing danger of pollution of all ground waters by the bodies of the dead men and animals and the refuse and filth of the camps4 ,the evils arising from these sources may be largely or entirely removed by boiling the drinking-water1 and the disagreeable tastes and smells may be removed by filtering through good filters4 ,it is very difficult1 however1 to compel the men to boil the water1 or to drink it after it is boiled1 unless it is properly aerated and filtered4 ,all available measures should1 therefore1 be adopted to supply them with wholesome water4 ,the results of the most recent researches show that properly conducted intermittent filtration with sand-filters will render a polluted water almost if not entirely safe4 7,see reports of ,massachusetts ,state ,board of ,health on ,purification of ,sewage and ,water1 #ahij47 ,and the analysis of water sterilized by a steam-jet at the ,columbian ,exposition in ,chicago1 #ahic1 gives reason to believe that this process may be very effective in removing disease germs4 7,see report of ,allen ,hazen1 ,chemist1 ,department of ,water-supply1 published in ,engineering ,news1 ,march #bi1 #ahid47 ,in camps of some permanence one or both of these processes may be well worth applying4 ,small filters for limited amounts of water may be bought in the market1 or may be improvised and set up for officers or company messes4 ,figs4 #ajh-aaj1 ,pl4 ,x1 are given as suggestions2 they serve as strainers in any case4 ,if used intermittently they may have a high sanitary value1 and if made up partly of either animal or wood charcoal they remove more or less completely any offensive taste or odor which water may have4 ,security1 however1 requires doubtful water to be boiled4 ,in all cases arrangements should be made to protect the water from surface pollution1 for convenient access for the men1 and for watering horses4 7,see the following books1 treating on ,military ,hygiene in ,camp and ,garrison3 ,parker's ,practical ,hygiene2 ,trait d',hygine ,militaire1 ,morache2 ,manuel d',hygine militaire1 ,viry2 ,military ,hygiene1 ,woodhull2 the ,soldier's ,pocket-book1 ,wolseley2 etc41 etc47 ,,part ,,ii4 ,,military ,,mining1 ,,blasting1 ,,and ,,demolition4 ,,chapter ,i4 ,,nomenclature ,,and ,,theory4 #a4 ,military ,mining includes all the operations necessary for placing charges of explosive underground and exploding them at the time desired1 for the purpose of destroying the men1 materials1 or works in their vicinity1 or for breaking up the surface of the ground either to advance or retard the operations of a siege4 ,the excavation for receiving the charge is called the chamber4 ,the approaches leading to the chamber when horizontal or somewhat inclined are called galleries1 and when vertical are known as shafts4 ,when very steep they are sometimes called slopes4 ,the charge1 chamber1 and approaches taken together constitute a mine4 ,the pit formed by the explosion is called the crater4 ,when the ground is homogeneous and its surface horizontal1 the intersection of its surface by the crater is approximately a circle1 the radius of which is called the crater radius1 ,,ab1 ,pl4 ,,xi1 ,fig4 #a4 ,the right line joining the centre of the charge with the nearest point of the surface toward which the explosion will take place1 generally the surface of the ground1 is called the line of least resistance 7written generally ,l4 ,l4 ,r471 ,c ,b1 ,pl4 ,,xi1 ,fig4 #a4 ,a right line from the centre of the charge to the edge of the crater is called the radius of explosion1 ,c ,d1 ,pl4 ,,xi1 ,fig4 #a4 ,the distance from the centre of the charge at which an ordinary mining gallery will be broken in by the explosion is called the radius of rupture1 ,c ,l1 ,pl4 ,,xi1 ,fig4 #c4 ,the radius of rupture varies in length with its inclination to the horizontal4 ,craters whose diameters are once1 twice1 etc41 their lines of least resistance are called one-lined1 two-lined1 etc41 craters4 ,mines in which the ,l4 ,l4 ,r4 is equal to the crater radius are called common mines4 7,their craters are two-lined47 ,those in which the crater radius exceeds the ,l4 ,l4 ,r4 are called overcharged mines or globes of compression2 when it is less1 they are undercharged mines2 and when the charge is so small that no exterior crater is formed1 they are known as camouflets4 #b4 ,in the explosion of military mines on land it may safely be assumed that the circumstances of combustion of the charge when fired are such that the energy developed is directly proportional to the charge4 ,a portion of this energy is generally lost by the escape of the compressed gases into the air1 by the heat given up to the surrounding media1 and by the transmission of earth-waves or shock2 the remainder and greater part1 however1 is expended in rupturing the case containing the charge1 compressing the soil in its immediate vicinity1 separating that lifted up from that forming the sides of the crater1 breaking up the portion thrown out into large or small fragments1 projecting them to a greater or less distance1 and disintegrating the soil around the crater to a distance which varies with the soil and with the quantity and character of the explosive used4 ,as the proportional part of the energy expended in each of the effects above named cannot be determined in any particular case1 and as each case differs in some respect from every other1 it is manifestly impossible to express in any mathematical formula a rule for determining the exact amount of explosive required for any particular mine4 ,from the results of long experience1 however1 engineers have concluded that computations sufficiently exact for practical purposes can be made upon the hypothesis that for common mines and those approximating closely to them in form1 the volumes of the craters are directly proportional to the charges used4 #c4 ,in order to apply this rule in practice the volumes of craters formed by known charges must be measured2 but since the soil in the immediate vicinity of the crater is more or less disintegrated1 and the crater itself is partly filled up by the material which falls back into it1 the outlines of the original crater cannot usually be recognized or its exact geometrical figure be determined4 ,besides1 the craters formed under circumstances seemingly identical differ more or less among themselves4 ,for convenience in computation1 however1 several simple geometrical figures have been assumed as giving with sufficient accuracy the form of the crater of a common mine4 ,see ,pl4 ,,xi1 ,fig4 #a4 ,among these ,vauban assumed a cone1 ,,acd1 with its vertex at the centre of the charge2 ,valire a paraboloid of revolution1 ,,ahd1 with its focus at the centre of the charge2 ,mller truncated this paraboloid by a horizontal plane through its focus2 while ,gumpertz and ,lebrun adopted the form in common use at their time1 and which has been generally accepted since1 viz41 a frustum of a cone1 ,,aefd1 the smaller base of which passes through the centre of the charge and has a radius1 ,,ec1 equal to one-half the crater radius1 ,,ab 7or one-half ,l4 ,l4 ,r41 ,,cb74 ,the volumes of these figures are as follows3 ,vauban's cone #a4je 7,l4 ,l4 ,r47#c1 ,valire's paraboloid #a4ij 7,l4 ,l4 ,r47#c1 ,mller's truncated paraboloid #a4hd 7,l4 ,l4 ,r47#c1 ,the frustum of a cone #a4hc 7,l4 ,l4 ,r47#c nearly 7#aa_/f77,l4 ,l ,r47#c4 ,the cone of ,vauban 7lately assumed also by ,hfer7 was abandoned as unsatisfactory1 because it did not conform to the craters produced1 and1 as treated by ,hfer1 because the charges computed by its use were found to be too small 7an error in the wrong direction74 ,the paraboloid of ,valire or ,mller would seem to conform more nearly to the actual shape assumed by the crater2 but it will be observed that the volume of the latter is sensibly the same as that of the truncated cone1 and as the volume of earth thrown out is the quantity to be considered1 the truncated cone will be assumed as the measure for it4 #d4 ,the principle that 8the volumes of the craters are proportional to the charges used0 is the general statement of the miner's rule4 ,assume ,c and ,c to represent the charges of two mines whose volumes are ,v and ,v1 lines of least resistance l and l1 and crater radii r and r4 ,assume also that the craters are frustums of cones1 the radii of whose larger bases are twice those of the smaller4 ,then ,c 3 ,c 33 ,v 3 ,v 33 7#aa_/f77lr#b7 3 7#aa_/f77lr#b71 or ,c ,c 7,v_/,v7 ,c7#aa_/f77lr#b7_/7aa_/f77lr#b7 ,c7lr#b7_/7lr#b7 444 7#a7 ,equation 7#a7 is applicable to mines in which r does not differ materially from l or r from l4 ,from an experimental mine giving a crater of this general type the relations between ,c1 l1 and r may be determined1 and assuming any two of the quantities ,c1 l1 and r for a mine with a crater nearly similar in form1 the other may be found from eq4 7#a74 ,when l r and l r1 we have ,c 3 ,c 3 37#aa_/f7l 3 7#aa_/f7l#c1 and ,c ,c7#aa_/f77l#c7_/7aa_/f77l#c7 ,c7l#c7_/7l#c7 7#b7 ,equation 7#b7 is applicable to common mines1 and shows that in common mines the charge varies as the cube of the line of least resistance4 ,assuming ,c as the charge which will produce a crater with a volume of unity1 equations 7#a7 and 7#b7 become1 by omitting the primes from l and r1 ,c ,c7#aa_/f7lr#b1 7#c7 and ,c ,c7#aa_/f7l#c 7#d7 ,equation 7#d7 gives the rule for determining the charge for common mines whose ,l4 ,l4 ,r4 is given1 viz43 ,multiply #aa_/f1 the cube of the line of least resistance in yards1 by the quantity of explosive required to throw out one cubic yard4 ,the latter quantity is determined by experiment4 ,a similar rule may be written out from eq4 7#c7 for mines differing but little from common mines4 #e4 ,the quantity of gunpowder required to throw out a cubic yard of material has been calculated from a great number of mines fired in different kinds of soil4 ,the following table gives the quantities required according to ,lebrun and ,macaulay1 respectively the ,french and ,english authorities on the subject3#h ,,table ,a4 ,number4 ,description of ,earth1 ,rock1 or ,weight per ,charge1 ,charge1 ,proportional ,masonry4 cubic foot4 ,gumpertz ,macaulay4 value and ,lebrun4 of charge4 lbs4 lb4 oz4 lb4 oz4 #a ,light sandy earth 7common earth1 #he #a4h #a4ac #a4ab ,lebrun7 #b ,hard sand #aaa #a4aj #b4j #a4be #c ,fat earth mixed with sand and gravel 7common earth1 ,macaulay7 #aaf #a4e #a4aj #a4jj #d ,wet sand #aah #a4ab #b4b #a4cj #e ,earth mixed with stones #aah #a4ad #b4d #a4dj #f ,clay mixed with tufa #abd #b4a #b4h #a4ee #g ,fat earth mixed with pebbles #adc #b4d #b4ab #a4fi #h ,rock #adc #c4j #c4aj #b4be #i ,new or old moist brickwork or masonry #b4b #a4cj #aj ,inferior brickwork or masonry #b4aa #a4ff #aa ,good1 new ditto #c4aj #b4be #ab ,good1 old ditto #d4a #b4ej #ac ,roman ditto1 or other equally good in warm climates #d4aa #b4ij #f4 ,for common mines in ordinary earth a convenient rule1 very generally used1 and which gives results nearly the same as those deduced from the table1 is3 ,the charge of gunpowder in pounds is equal to one tenth the cube of the line of least resistance in feet1 or ,c lbs4 7#a_/aj7l#c ft4 7#e7 ,,overcharged ,,and ,,undercharged ,,mines4 #g4 ,for overcharged and undercharged mines in which the ,l4 ,r4 ,r4 and crater radius differ materially in length the results deduced from the preceding equations are not applicable4 ,for such mines the following equations1 due to ,gumpertz and ,lebrun1 are in common use1 viz43 ,for an overcharged mine1 ,c ,c7#aa_/f7l 7#g_/h77r - l7#c4 7#f7 ,for an undercharged mine1 ,c ,c7#aa_/f7l 7#g_/h77l - r7#c4 7#g7 ,in which ,c charge of explosive in pounds1 l ,l4 ,l4 ,r4 in yards1 r crater radius in yards1 ,c amount of explosive in pounds necessary to throw out one cubic yard of earth in a common mine in the same soil4 ,these formul are deduced as follows1 viz43 ,it was found by experiments made independently by ,belidor and ,marescot that #cffj lbs4 of powder in a mine with ,l4 ,l4 ,r4 equal to #d yards gave a crater with a radius of #ab yards in earth requiring for a common mine #a lbs4 of powder per cubic yard4 ,the charge for a common mine in the same soil with ,l4 ,l4 ,r4 equal #d yards is 7#aa_/f77d yds47#c 7#a7 #agf lbs4 ,representing by l the ,l4 ,l4 ,r4 for a common mine requiring a charge of #cffj lbs41 since the charges of common mines are proportional to the cubes of their lines of least resistance1 we have #agf 3 #cffj 33 #dc 3 l#c #accj4h1 whence l #aay2 #aac #acca4 ,to find from these data the relations between charges for overcharged mines1 construct ,figs4 #b and #b;a1 7,pl4 ,,xi47 ,fig4 7#b7 gives mines with crater radii of #dy and #aby and a common ,l4 ,l4 ,r4 of #dy4 ,divide the distance between ,a and ,b into four equal parts1 and assume the points of division as the extremities of the crater radii of overcharged mines1 each of which exceeds the one next smaller by 77,,ab1 and all corresponding to a ,l4 ,l4 ,r4 of #dy4 ,fig4 7#b;a7 gives common mines with lines of least resistance of #dy and #aay4 ,divide the distance ,a,b also into four equal parts1 and assume the points of division as the extremities of the crater radii of common mines each of which exceeds the one next smaller by 77,a,b4 ,since the charges for the common mines whose lines of least resistance are respectively #dy and #aay are identical with those of the overcharged mines whose crater radii are #dy and #aby respectively1 it is assumed that the charges for the intermediate common mines are the same as would be required to produce the corresponding intermediate overcharged mines4 ,the increment of the crater radius and line of least resistance of any one of these common mines is equal to #g_/h the increment of the crater radius of the corresponding overcharged mine2 consequently the charge which gives an overcharged mine whose ,l4 ,l4 ,r4 and crater radius are l and r1 respectively1 will produce a common mine whose ,l4 ,l4 ,r4 l will be given by the equation l l 7#g_/h77r - l74 7a7 ,since the charge for a common mine is obtained from equation 7#d71 ,c ,c#a7aa_/f7l#c1 the charge for the overcharged mine will be ,c ,c#a7aa_/f7l 7#g_/h77r - l#c1 as above4 ,for ordinary earth and gunpowder1 when ,l4 ,l4 ,r4 is measured in feet1 eqs4 7#f7 and 7#g7 become1 respectively3 ,for an overcharged mine1 ,c 7#a_/aj7l 7#g_/h77r - l7#c 7#f7 ,for an undercharged mine1 ,c 7#a_/aj7l - 7#g_/h77l - r7#c 7#g7 #h4 ,giving to l the same value in equations 7#d71 7#f71 and 7#g71 we have ,c ,c77#g_/h7r_/l 7#a_/h77c1 7#h7 ,in which ,c charge for common mine with ,l4 ,l4 ,r4 and crater radius l4 ,c charge for over or undercharged mine with ,l4 ,l4 ,r4 l and crater radius r4 ,equations 7#f71 7#g71 and 7#h7 having been deduced from the relations existing between ,c1 l1 and r for mines varying from common mines up to those in which r #cl may safely be used for overcharged mines up to this limit4#i ,in their applications to undercharged mines they become uncertain when r 77l2 and when r 77l the computed charge generally produces a camouflet4 ,these computed charges are3 for r 77l1 ,c #j4aggi;,c2 for r 77l1 ,c ,o4#afcf;,c4 ,a rule of the ,french engineers states that a charge which will produce a common mine with ,l4 ,l4 ,r4 l will produce a camouflet if the ,l4 ,l4 ,r4 is increased to 7#g_/d7l4 ,at this depth ,c #j4ahg;,c1 and the formula gives a crater radius of #be_/di4 ,as a safe 8rule of thumb10 we may assume that a charge which will give a common mine with ,l4 ,l4 ,r4 l will give a camouflet with ,l4 ,l4 ,r4 #bl 7r from formula 7#c_/g7l74 ,conversely1 a camouflet will be produced by of the charge which will produce a common mine4 #i4 ,radius of ,rupture4--,the determination of the radius of rupture is an important consideration in underground warfare1 since1 when it is known1 miners may so place their chambers as to break in the galleries of the enemy without injuring their own4 ,as different mining galleries1 however1 differ from each other so much in strength to resist crushing1 and as the cost of an exhaustive series of experiments to determine their relative strength would be so great both in time and money1 but little well-established data exist upon which to found a rule for determining the radius of rupture4 #aj4 ,the rule deduced by ,gumpertz and ,lebrun1 however1 from the material available at their time corresponds very nearly with the results of later experiments and observations1 and is generally admitted as sufficiently near correct for practical use4 ,this rule is based upon the theory that the surface of rupture is an oblate spheroid1 7,pl4 ,,xi1 ,fig4 #c71 with its axis of revolution vertical and its centre at the centre of the charge2 the intersection with the surface of the ground ,,ad coinciding with the edge of the crater4 ,the ratio between the semi-transverse axis ,,cf and the semi-conjugate axis ,,ch of the generating ellipse of this assumed spheroid is the same as that between the radius of explosion ,,cd and ,l4 ,l4 ,r41 ,,ck4 ,the rule is1 that the radius of rupture in any direction is equal the corresponding radius of this spheroid4 ,from the conditions assumed the following values of the semi-transverse and semi-conjugate axes h and v 7which are the horizontal and vertical radii of rupture7 are obtained1 viz43#aj h l7#a #b7r_/l7#b72 v l7#a #b7r_/l7#b7_/7a 7r_/l7#b74 ,for common mines these formulas give3 h #a4gcbl 7#g_/d7l 7#g_/d7r2 v #a4bbel 7#e_/d7l 7#e_/d7r4 ,for six-line craters1 h #d4cehl 7#ce_/h7l 7#c_/b7r2 v #a4cghl 7#aa_/h7l 7#a_/b7r4 #aa4 ,the ,english authorities adopt the value of 7#g_/d7l for the horizontal and l 7#b7 #a4dadba l 7#g_/e7l for the vertical radius of rupture of all classes of mines4 ,in which l ,l4 ,l4 ,r4 of an equivalent common mine l 7#g_/h77r-l71 etc4 ,some later experiments at ,chatham have given v 7#e_/c7l for a #d-lined crater2 v #bl for a #e-lined crater2 and v 7#e_/b7l for a #g-lined crater4 #ab4 ,there are other good reasons for believing that ,lebrun's value for the vertical radius is too small2 but as its use leads to increasing the charges designed to produce crushing effects1 the error1 if it exists1 is in the right direction1 and justifies the use of the formula until more exact data are available4 ,,explosives4 #ac4 ,no military mining operations of note have been carried on since the introduction of dynamite and other high explosives2 consequently our knowledge of their value for work of this kind rests entirely upon the results obtained from experimental mines4 ,unfortunately but few experiments seem to have been made1 and the published results of these are very meagre4 #ad4 ,two mines fired at ,krems in #ahgc with ,l4 ,l4 ,r4 of #ab ft4 in earth weighing #ajj lbs4 per cubic foot and charged1 one with #agc lbs4 gunpowder1 the other with #eh lbs4 dynamite 7kind not stated71 gave crater radii1 respectively1 of #ab4ge and #aj4be feet4 ,lebrun's formulas applied to these give to gunpowder and dynamite the ratio #a 3 #a4fhh4 ,two powder-mines and one dynamite-mine1 each of #ab ft4 ,l4 ,l4 ,r41 were fired at ,willet's ,point in #ahgh4 ,the powder-mines were each charged with #bjj lbs4 cannon-powder and the dynamite mine with #hb lbs4 dynamite ,no4 #a4 ,no4 #a powder-mine gave a crater radius of #ae ft4 ,no4 #b powder-mine gave a crater radius of #ae ft41 or a mean of #ae ft4 ,the dynamite-mine gave a crater radius of #ad ft4 ,the relative values of cannon powder and dynamite resulting from the application of the same formulas to these mines is #a 3 #a4iig4aa #ae4 ,choice of ,explosive4--,from these experimental mines it may be concluded that for forming craters in ordinary earth dynamite is not quite so efficient as double its weight of good gunpowder4 ,for breaking up hard rock1 blowing up strong masonry1 and especially in demolitions where tamping is usually defective1 this ratio does not hold2 but the relative effect of the high explosive increases continually with the lack of tamping and the intensity of the local blow desired1 until a point is reached at which the effect of gunpowder is almost imperceptible1 while the high explosive does efficient work4 ,this property of the high explosives renders them extremely valuable for use in hasty demolitions1 such as blowing up palisades or barriers1 destroying guns1 etc41 etc4 ,owing to their varying values in different conditions the choice of explosive to be used in any particular case must evidently depend upon the circumstances attending it4 ,in underground explosions both gunpowder and high explosives give out noxious gases which penetrate the soil1 and which entering a gallery in sufficient quantity would suffocate the miners4 ,of these gases the carbonic oxide given off by some of the high explosives is probably the most dangerous to human life1 and if mixed with the proper proportion of air forms an explosive mixture1 resembling in this respect the fire-damp of the coal-mines4 ,whether in practical mining operations it would ever be retained in the soil in such quantities as to produce this effect remains to be seen4 ,some of the high explosives1 on the other hand1 seem to produce relatively small quantities of noxious gases4 ,the gases produced by gunpowder1 while suffocating in their nature1 have the advantage of always making their presence known by their odor4 #af4 ,for use in overcharged mines designed to break in the enemy's galleries1 the high explosives1 from the violent character of their explosion and from the phenomena exhibited in submarine mining1 promise to give relatively greater radii of rupture than gunpowder2 but sufficient data are not available to state this positively4#ab #ag4 ,beside the considerations above stated1 which refer to the effects produced by the explosive when fired1 there are others equally important relating to the safety and facility with which the explosive may be transported1 handled1 and placed in the mines4 ,the latter will frequently have greater weight than the former in determining the explosive to be used in any particular case which may arise in the practical operations of mining4 ,of the latter considerations some of the most important in deciding whether to use gunpowder or high explosives are the following1 viz43 ,gunpowder is easily obtained1 and most enlisted men are more or less familiar with its properties4 ,it explodes when ignited by fire4 ,it does not ordinarily explode when struck by a bullet4 ,it is injured by moisture and destroyed by thorough wetting4 ,it is not affected by ordinary changes of temperature4 ,it requires thorough tamping to produce good effects4 ,many high explosives are not injured by moisture1 and some are unaffected by total immersion in water4 ,they generally burn without detonation if ignited by flame4 ,some of them do not explode when struck by a bullet4 ,the more sensitive ones do4 ,the properties of some of them are materially changed by freezing4 ,on account of their greater strength1 the same effects may be produced by smaller charges1 requiring smaller chambers and cases4 ,by reason of the violence of their action they produce good results even if imperfectly tamped4 ,the last two considerations1 together with the possibility of using them in wet places without protection against moisture1 lessen greatly the time required to excavate1 charge1 and tamp a mine1 and may frequently enable the one using them to anticipate an enemy using gunpowder and thus secure success1 when the use of gunpowder would reverse the situation4 ,in mining operations and in expert hands the high explosives1 upon the whole1 seem to cause fewer accidents than gunpowder4 ,,chapter ,,ii4 ,,practical ,,operations ,,and ,,details4 #ah4 ,tools and ,appliances4--,the different operations of mining are carried on by the use of picks1 shovels1 bars1 saws1 axes1 hammers 7large and small71 chisels1 wheel and hand barrows1 windlasses1 ropes1 wooden or leather buckets1 gauge-sticks1 mason's levels 7,pl4 ,,xi1 ,fig4 #d71 plumb-lines1 candles1 closed lanterns1 tin pipes1 rubber and canvas hose1 canvas1 nails1 etc41 etc41 of the kinds in common use2 and the following special tools and appliances1 viz43 ,the ,miner's ,pick4 ,smaller and lighter than the common pick4 ,neither its head nor its handle exceeds #b feet in length4 ,the ,miner's ,shovel4 ,similar in shape to a common shovel1 but not exceeding #b feet in length4 ,the ,push ,pick 7,pl4 ,,xi1 ,fig #e71 which has a lance-shaped blade about #c in4 wide and #f in4 long attached to a handle about #b feet long4 ,the ,field ,level 7,pl4 ,,xi1 ,fig #f71 which consists of three strips of wood about #b 1 arranged as shown4 ,the strip ,a is #d' between centres of pins2 ,b and ,c are #b'1 #i-ae_/af2 the angle at a #ij4 ,a spirit-level is inserted in piece ,c1 and a plumb-line attached as shown4 ,the markings on ,a are used for gentle slopes1 those on ,b for steep ones4 ,the other sides of ,b and ,c are divided into degrees of arc1 the centre being at the middle point of the outside edge of ,a4 ,the ,slope ,block1 which is a wooden cube used in connection with a mason's level for fixing slopes4 ,angle ,templets 7,pl4 ,,xi1 ,fig4 #g71 making a definite angle1 used in laying out galleries4 ,the ,miner's ,truck or ,car4 ,a small1 four-wheeled wagon with fixed axles and very short wheel-base2 exterior dimensions about #bj wide1 #ah to #bj high1 and #cj long4 ,used for carrying earth through galleries1 and usually hoisted up the shaft and dumped outside1 replacing the buckets used in sinking the shaft4 ,the ,miner's ,bellows 7,pl4 ,,xi1 ,fig4 #h74 ,a leather bag with wooden top and bottom1 provided with inlet and outlet valves1 from the latter of which the air is led off in pipes or hose4 ,in using the bellows the miner stands upon the lower handles and works the bellows with his hands by the upper ones4 ,this is frequently replaced by a common blacksmith's bellows or the rotary blower from a portable forge2 and sometimes by an improvised air-pump1 consisting of a large open cask filled with water and another smaller one1 with one head removed and the other provided with outlet and inlet valves and an air-tube1 inverted over the large cask1 supported by a spring-pole and worked up and down by hand in the water of the lower cask4 ,the ,miner's ,candlestick 7,pl4 ,,xi1 ,fig4 #i71 which holds a candle1 and may be driven into the side or bottom of a gallery4 ,miner's ,lamps 7,pl4 ,,xi1 ,fig4 #aj71 can be used only when the ventilation is good1 as they give off more smoke than candles4 ,when an electric-light plant is available1 incandescent lamps will be used for mining4 ,earth ,augers1 similar to those used for boring post-holes1 but of different diameters1 are sometimes used for placing camouflets4 ,their shanks are made in short lengths1 which can be joined together to allow of boring a deep hole from a narrow shaft or gallery4 ,,galleries ,,and ,,shafts4 #ai4 ,the ,dimensions of ,galleries and ,shafts are determined by the use to be made of them1 the necessity of ventilation1 and the minimum space in which a man can work4 ,they are usually about as follows1 viz43 ,height1 ,width1 feet4 feet4 #a4 ,great or grand galleries #f #g #b4 ,common galleries #f #c #c4 ,half galleries #d #c #d4 ,branches #c #b #e4 ,small branches 7rameaux de combat74 #b #b ,shafts vary in size--from the smallest in which a man can work 7about #b' #d'71 to any size that may be required1 seldom exceeding #aj' #aj'4 ,great galleries are used for descent into a ditch1 and when it is wished to pass cannon through them4#ac ,common galleries are used for descent into a ditch1 and for communications4 ,troops can pass through them 8by twos40 ,half galleries answer for general purposes of attack4 ,they allow the miner to work freely in different positions without being cramped1 but are small enough to admit of rapid driving4 ,branches and small branches are driven out from the galleries to the mine-chambers1 etc4 ,they can be driven rapidly for short distances 7#aj to #bj feet72 but when of greater length the earth is removed from them with difficulty1 they are not easily ventilated1 and are too small for use as communications4 #bj4 ,shaft and ,gallery ,linings4--,in very firm soil it is sometimes practicable to drive small shafts and galleries short distances without lining them2 but if these are to stand for any length of time1 there is always danger of their falling in1 particularly if shaken by the explosion of mines in their vicinity4 ,when it is considered safe to use them1 however1 the shafts should be elliptical in plan1 and the roofs of the galleries should be pointed arches4 ,as a rule1 however1 both shafts and galleries should be lined4 ,those which are permanent in their character--as the main galleries of the countermines of a permanent work--are lined with masonry4 ,masonry linings may be of brick1 stone1 or concrete walls and arches4 ,the smaller galleries constructed during a siege1 and all the shafts and galleries of the attack1 are lined with wood4 ,wooden linings are of two general types1 known as cases1 and frames and sheeting4 #ba4 ,cases 7,pl4 ,,xi1 ,figs4 #aa and #ab7 are made of plank1 from #f to #ab wide1 each case consisting of a cap-sill1 a ground-sill1 and two stanchions4 ,the cap and ground-sills are cut to a length equal to the clear width of the shaft or gallery plus twice the thickness of the stanchions2 a rectangular notch is cut in each end to receive a corresponding tenon cut on the stanchion4 ,the length of the stanchions between shoulders is equal to the clear length of the shaft or height of the gallery4 ,the length of the tenons is generally equal to the thickness of the cap and ground sill 7usually #b71 and their width about three inches4 ,notches are cut in the sides of all the pieces of the case1 as shown in the figure1 for convenience in handling them4 ,in grand galleries the tenons at the top of the stanchions are usually shorter than the thickness of the cap-sill1 and those at the bottom1 as well as the mortises in the ground-sill1 are omitted4 ,the stanchions are kept from collapsing by blocks nailed to the ground-sills4 ,these blocks are #b thick1 and wide enough 7about #i7 to so guide the wheels of a gun-carriage as to prevent the axle striking the stanchions4 ,in cases for smaller galleries also the tenons are sometimes omitted at the bottom of the stanchions1 the mortises in the ground-sills cut an inch or two deeper1 and the stanchions kept from collapsing by keys driven in the mortises 7,pl4 ,,xi1 ,fig4 #ac74 #bb4 ,shaft and ,gallery ,frames 7,pl4 ,,xi1 ,figs4 #ad1 #ae1 and #af7 are made of scantlings1 halved together at the ends1 as shown in the figures4 ,sheeting is made of boards or planks of the necessary thickness1 sawn to proper lengths1 and bevelled at the ends4 ,when sawn lumber is not available1 the frames may be made of saplings1 and in some cases poles may be used for sheeting4 ,the middle of each cap and ground sill1 both in frames and cases1 is distinctly marked by a shallow saw cut or otherwise4 #bc4 ,the following table gives the dimensions1 in inches1 usually adopted for the pieces of cases1 frames1 and sheeting1 for galleries of different sizes1 viz43 ---------------------------------------- ---------------------------------------- ----------------- ,cases4 ,frames and ,sheeting4 ---------------------------------------- ------------------------------------ ,ground-sill4,stanchions4 ,cap-sill4 ,ground-sill4,stanchions4,cap-sill4,shee ting4 ---------------------------------------- ---------------------------------------- ------------ ,in4 ,in4 ,in4 ,in4 ,in4 ,in4 ,in4 ,great galleries #c #d #e #f #d #f #f #f #i #b ,common galleries #b #b #b #f #c #f #f #f #h #a ,half galleries #b #b #b #e #c #e #e #e #g #a ,branches #a or #b #a or #b #a or #b #d #c #d #d #d #e #a or #a ,small branches #a to #b #a to #b #a to #b #c #c #c #c #c #d #a ---------------------------------------- ---------------------------------------- ------------ ,the cases of branches and small branches are sometimes made very strong1 with a view to resist rupture by the explosion of neighboring mines4 ,for this purpose cases made of oak plank #d thick are used1 and the branch near its end is packed full of scantlings provided with rope-handles at their ends for withdrawing them after the mine is fired4 ,this packing is1 however1 of doubtful utility1 since a compression of the case sufficient to call the resistance of the packing into play is very apt to produce a permanent deformation of the cases1 which will jam the scantlings and prevent their removal4 ,for convenience in use the pieces of cases should be of uniform width4 #bd4 ,relative ,advantages of ,cases1 and ,frames and ,sheeting4--,in favorable soil1 cases1 when they can be obtained1 allow of more rapid progress and give a lining with a smooth interior4 ,in very bad soil they cannot be used for the larger galleries4 ,frames and sheeting can be used in all soils which admit of mining operations1 and can usually be improvised from materials found in the vicinity4 #be4 ,sinking a ,shaft by ,frames and ,sheeting4--,the size and position of a shaft are usually determined by the character and direction of the gallery which is to start out from it4 ,it is evident 7,pl4 ,,xi1 ,fig4 #ag7 that the clear width of the shaft must be enough greater than the outside width of the gallery to allow the side sheeting of the gallery to be freely inserted outside the frames of the gallery and inside those of the shaft2 also1 that the shaft frames must be so spaced as to leave a clear space at the bottom for the gallery4 ,this space must be equal to the clear height of the gallery1 increased by the thickness of the cap-sill1 the sheeting1 and one or two inches for easy working4 ,this and the thickness of one frame being deducted from the depth of the shaft1 the remainder may be divided up into a number of equal or unequal parts called shaft intervals4 ,in order that the sheeting may not yield under the pressure of the earth1 these intervals seldom exceed #d feet4 ,the length of the shaft must be great enough to allow the miners to work freely1 and to insert the sheeting for the first gallery interval4 ,the sheeting for both shafts and galleries is cut in lengths about #a foot greater than the interval between frame centres4 #bf4 ,the size and position of the shaft having been fixed1 the top frame 7,pl4 ,,xi1 ,fig4 #ae7 is placed in position and secured by pegs1 and the direction of its axis is accurately fixed by the score marks at the middle of the end pieces4 ,the side and end pieces of this frame are respectively about #c feet longer than those of the other frames1 and are so halved together as to make of their ends four projecting horns1 #a' long1 which keep the frame in place during the excavation of the first interval4 ,this frame is usually placed with its top flush with the surface of the ground4 ,the miner proceeds to excavate the shaft with pick and shovel1 making it large enough in plan to admit the sheeting outside the frame4 ,usually the first interval can be excavated without supporting the earth at the sides1 which are vertical or slightly undercut1 so that at the bottom of the interval the shaft will be large enough to admit the second frame1 the sheeting of the first interval1 and a system of wedges which hold this sheeting out from the second frame a distance somewhat greater than the thickness of the sheeting of the second interval4 ,the verticality of the sides is determined by the plumb-line1 and the size of the shaft by two gauge-sticks cut respectively to the outside length and width of the excavation1 and distinctly marked at their centres4 ,to avoid the inconvenience of working under the top frame1 the first interval is frequently marked out and excavated before the frame is fixed in its position4 ,when the shaft is deep enough the second frame is put in place and nailed together2 the notches in the ends of the side pieces turned upward and those of the end pieces downward4 ,the top and second frame are connected by nailing to them four battens of proper length 7two on each side71 which suspend the second frame from the top frame at the established interval4 ,the second frame is placed vertically below the top frame by using the plumb-line and the scores in the frames4 ,the sheeting is inserted outside the top frame1 bevelled end first1 bevel outside1 and pushed down until its top is flush with the top frame4 ,the lower end of the sheeting is held out from the lower frame by suitable wedges1 and the excavation of the second interval is commenced4 ,in ordinary soil the sides of the shaft will now require support4 ,sheeting is therefore introduced and pushed down as the excavation proceeds1 and the wedges previously placed are removed to make room for the sheeting4 #bg4 ,if the pressure of the earth becomes great enough to spring the sheeting-planks inward1 an auxiliary frame is introduced4 ,this is a frame similar to the shaft frames1 but from #d to #f inches larger in outside dimensions4 ,the sheeting rests directly against the outside of this frame1 and is thus held out far enough to allow the third frame to be placed and the wedges to be inserted as before4 ,the auxiliary frame is then removed and used in the next interval4 #bh4 ,successive frames are placed in the same manner until the one directly over the gallery is reached4 ,great care is taken to place this frame at exactly the right height1 and the shaft is then continued to the required depth4 ,a frame is placed at the bottom with its top at the level of the floor of the gallery1 and the sheeting is allowed to rest directly against the outside of this frame4 ,when the soil will allow it1 the sheeting is omitted wholly or in part over the portion of the shaft which is to form the gallery entrance4 #bi4 ,precautions4--,in sinking shafts especial care must be taken to make the excavation no larger than is required for placing the lining1 since if a vacant space is left outside the lining the sides of the shaft may give way through its entire height1 and fall against the lining with a blow which will crush it in4 ,this is often the cause of fatal accidents both in shafts and galleries4 #cj4 ,partly-lined ,shafts1 i4e41 those in which the sheeting-planks are separated from each other by greater or less intervals1 should only be used for small depths and when they are expected to stand for a very short time4 ,they are a constant menace to the miners1 owing to the danger of their caving in1 and in a much greater degree to the probability of stones1 etc41 falling from the unprotected parts and seriously injuring or killing the men at the bottom4 #ca4 ,driving a ,gallery with ,frames and ,sheeting4--,the direction of the gallery has already been marked by the scores on the shaft frames2 but it must be verified by plumb-lines1 and two small pickets be driven on the line of its axis1 which is located exactly by small nails1 one driven in the head of each picket4 ,two gauge-rods are prepared1 giving the extreme height and breadth of the excavation1 i4e41 the height of the frame plus two thicknesses of top sheeting1 and the breadth of the frame plus four thicknesses of side sheeting4 ,the middle of each gauge-rod is also plainly marked4 ,a gallery frame is set up against the side of the shaft 7,pl4 ,,xi1 ,fig4 #ag71 its ground-sill flush with the bottom frame of the shaft2 or its stanchions may rest upon the shaft frame as a ground-sill4 ,the gallery frame is carefully located and fastened in position with battens and braces4 ,the shaft sheeting is then forced down two or three inches with a bar1 and the top sheeting of the gallery inserted and driven in until its end is supported by the earth4 ,it is given the proper upward pitch by a scantling laid across it and secured to the shaft frames4 ,the shaft sheeting is forced further down1 the earth at the top excavated1 and the top gallery sheeting advanced4 ,as this work proceeds the side sheeting-planks are successively inserted and driven forward4 ,in this way the gallery is advanced one gallery interval1 usually about #d feet1 when a second frame is placed4 ,its position is verified by the score marks2 for direction1 by a line2 for grade1 by a spirit1 mason's1 or field level2 and for verticality1 by a plumb-line4 ,it is then secured in place by nailing battens to it and the preceding frame4 ,wedges are inserted between the frame and the sheeting1 and the gallery is continued by the same methods 7,pl4 ,,xii1 ,fig4 #ai74 ,when the sheeting is advanced only by hard driving the frames are slightly inclined to the rear at first1 and are afterwards driven forward until vertical4 #cb4 ,if1 while advancing the sheeting1 the pressure upon it becomes so great as to spring it1 a false frame 7,pl4 ,,xii1 ,fig4 #ah7 must be used4 ,this consists of a cap-sill1 ground-sill1 and two stanchions1 connected by mortises and tenons4 ,the stanchions have tenons and the sills mortises at each end4 ,the cap-sill is usually rounded on top and1 for facility in setting up and removing1 its mortises are longer than the width of the tenons4 ,the latter are held in place by wedges when the frame is in position4 ,the false frame is usually made of the same height as the common frames and1 when side sheeting is used1 wider by twice the thickness of this sheeting4 ,when side sheeting is not used1 its outside width may be equal to the clear width of the gallery4 ,in using the frame 7,pl4 ,,xii1 ,fig4 #ai7 the ground-sill is first placed accurately in position at a half interval in advance1 the stanchions are set up1 and the cap-sill placed upon them and wedged4 ,the whole frame is then raised about #b inches by folding wedges placed under each end of the ground-sill1 and is secured by battens4 ,the sheeting will now rest directly upon the cap-sill and stanchions1 and have the proper inclination to clear the next frame by its own thickness1 as is required4 ,the next frame is then set up1 the wedges driven under the sheeting1 and the false frame removed2 which is easily done1 owing to its construction4 #cc4 ,when the soil is very bad a shield 7,pl4 ,,xii1 ,fig4 #bj7 is used to prevent the earth in front and above from caving into the gallery4 ,in starting out from the shaft the following method is adopted3 ,as soon as the top sheeting is sufficiently advanced and the shaft sheeting is forced down about #a foot1 the top plank of the side sheeting is inserted and driven forward about #b feet1 and the earth at the top of the gallery is excavated for from #f inches to #a foot in advance4 ,a piece of plank a foot wide and in length equal to the width of the gallery is then placed directly under the top sheeting and against the face of the excavation1 and is held in place by braces at its ends secured to the shaft lining4 ,the shaft sheeting is then lowered another foot1 the next plank of the side sheeting inserted1 the earth excavated1 and a second plank of the shield placed in the same way as before4 ,this is continued until the entire face is covered4 ,the top and side sheeting are then driven forward1 and the top plank of the shield is removed and replaced in advance2 after which each plank is removed and replaced in succession1 as above described4 #cd4 ,inclined ,galleries4--,method of fixing the slope4--,if the gallery instead of being horizontal is ascending 7,pl4 ,,xii1 ,fig4 #ba7 or descending 7,fig4 #bb71 the proper slope is obtained by using a slope-block whose edge is equal to the rise or fall of the gallery in one interval4 ,this is placed upon the lower of two consecutive ground-sills1 and the proper height of the other is determined by a mason's or spirit level 7,fig4 #ba74 ,if a field-level or a mason's level properly marked for the slope is used1 the slope-block may be dispensed with 7,fig4 #bb74 #ce4 ,position of ,frames4--,in driving descending galleries better progress will be made and less material used if the frames are set at right angles to the axis of the gallery 7,pl4 ,,xii1 ,fig4 #bb72 and this is the usual custom4 ,in driving ascending galleries this is impracticable1 and the frames are set vertically 7,fig4 #ba74 ,in all other respects inclined galleries are driven in the same manner as horizontal ones4 #cf4 ,partly-lined ,galleries4--,in very firm soil side sheeting may be omitted entirely1 and in that less firm the side planks need not be in contact4 ,when the side sheeting is omitted the width of excavation may be reduced to the clear width of the gallery1 and the stanchions be let into the side wall flush with its surface4 ,in this case the ground-sills are frequently omitted1 the stanchions resting upon wooden blocks1 stones1or directly upon the earth4 ,to save material1 the planks of the top sheeting are sometimes more or less separated also4 ,this can only be recommended when rapid and temporary work is required with limited materials2 and in these cases the earth between the planks should be supported by a packing of sticks1 brush1 etc41 etc4 #cg4 ,change of ,direction in ,galleries4--,in changing the direction of a gallery1 the new direction is laid off by using a carefully made angle-templet 7,pl4 ,,xi1 ,fig4 #g7 or slope-block1 field-level1 etc41 and it is prolonged in the new direction by the methods already described4 ,when the soil is firm enough to stand safely while excavating and lining one gallery interval1 even if somewhat short1 no difficulty exists in changing the direction of a gallery in either a vertical or horizontal plane1 since the excavation in the new direction may be made so large that the miner working in it can place the new frames and introduce the sheeting and wedges4 ,the gallery can then be carried on without diminution in size4 ,when the soil is bad1 however1 special arrangements must be made for introducing the sheeting4 #ch4 ,change of ,slope4--,to pass from a horizontal to an ascending gallery 7,pl4 ,,xii1 ,fig4 #ba7 it is only necessary to give the top sheeting the proper angle by holding down its back end with a piece of scantling placed across the gallery for that purpose2 and1 to give the side sheeting the proper inclination1 cutting trenches in the bottom of the gallery for the lower pieces1 if necessary4 ,in passing from a horizontal to a descending gallery 7,pl4 ,,xii1 ,fig4 #bb7 the roof may be carried forward horizontally1 and the floor given the desired pitch by increasing the height of the consecutive frames1 until enough head-room is obtained to allow the top sheeting for the descending gallery to be inserted at the proper height and angle4 ,the frame at this point is made with a cap-sill 7upon which the sheeting rests directly71 and a second cross-piece below it1 serving as a cap-sill for the descending gallery4 ,from this point forward the frames may be set perpendicular to the axis of the gallery1 as previously stated4 ,if the descending gallery is very steep and the horizontal pressure of the soil great1 it may be necessary to strengthen the stanchions of the last two or three vertical frames by cross-pieces near their upper ends4 #ci4 ,change of ,direction ,horizontally4--,slight changes of direction of narrow galleries1 either to right or left1 may be made in a manner entirely similar to that above described for descending galleries1 by widening the frames until the side sheeting can be inserted at the required angle1 and strengthening the cap-sills1 when necessary1 with additional stanchions4 ,when the gallery is wide or the changes of direction abrupt1 however1 it is customary to drive the gallery entirely beyond the turning-point1 and then break out a gallery in the new direction from the side of the original gallery4 #dj4 ,returns4--,a gallery starting out from the side of another is called a return1 and is rectangular or oblique according to the angle made by its axis with that of the original gallery1 which is called the gallery of departure4 ,that the return may be broken out1 the interval between the frames of the gallery of departure at this point must be such as to admit between the stanchions a frame and the side sheeting of the return 7,pl4 ,,xii1 ,fig4 #bc74 ,this part of the gallery of departure is called a landing1 and its floor is made horizontal4 ,if the return is oblique 7,fig4 #bd71 its width measured along the gallery of departure will be determined by an oblique section1 and may be so great that the strength of the lining of the gallery of departure will not allow the necessary length of landing4 ,in this case a short rectangular return is first broken out from the side of the gallery of departure1 and the new gallery is broken out from the side of this return 7,fig4 #be74 ,the latter method diminishes the length of the landing when the change of direction is less than #de4 #da4 ,the floor of a return is started at the level of the floor of its landing4 ,in firm soils which will stand for a short time without support the first frame may be set up entirely outside the gallery of departure 7,pl4 ,,xii1 ,figs4 #bd and #be7 and may be of the same height in clear as this gallery4 ,when the soil is bad1 however1 and side sheeting is required in the gallery of departure1 the first frame of the return must be set up against this sheeting in the interval between the stanchions of the landing 7,fig4 #bc74 ,this makes the clear height of the return at this frame less than that of the gallery of departure by a little more than the thickness of the sheeting4 ,the first frame of an oblique return should be so made that the sides of the stanchions will be parallel to the side walls of the return1 thus giving a good bearing to the side sheeting4 ,in very bad soil1 the first few frames of a return must be firmly braced to resist the backward thrust of the earth1 by battens connecting them together and by struts across the gallery of departure4 ,the latter are removed when the return is sufficiently advanced4 #db4 ,a ,complete ,map must be made of every system of mines1 showing the centres of shafts1 and the axes and slopes of all galleries2 giving also the references and lengths of all landings1 and the locations1 references1 and dimensions of all mine chambers4 #dc4 ,working ,drawings must also be made from which sheeting can be cut to proper lengths and angle-templets1 etc41 cut and framed4 ,these can be easily and accurately drawn by remembering that1 to allow the miners to insert the sheeting1 every return must have such dimensions outside its sheeting that1 if it were free to move1 its lining could be slid back across its landing as a drawer slides in a table4 ,the size of the landings and dimensions of frames having thus been determined1 the parts of the galleries between them may be divided into intervals1 which1 for convenience1 should be equal1 since this will allow the sheeting to be cut to a uniform length4 #dd4 ,sinking a ,shaft with ,cases4--7,pl4 ,,xii1 ,figs4 #bf and #bg47--;,a case of the required size is put together and accurately placed upon the site of the shaft1 whose dimensions are marked upon the ground outside it4 ,the case is then removed and the earth excavated to the depth of the case1 which is placed in the excavation with its top flush with the surface of the ground4 ,its position is carefully verified1 and it is secured in position by packing earth around it4 ,the excavation is then continued for the depth of another case1 which is put in place as follows1 viz43 ,one end piece is placed in position1 the tenons of the two side pieces are inserted in the mortises at its ends1 and the side pieces are pushed back into position2 a pocket-shaped excavation is made with a push-pick beyond the end of one of the side pieces and running back three or four inches into the side wall2 the remaining end piece is inserted in this far enough to allow the mortise at its other end to slip over its corresponding tenon2 it is then drawn back1 and the tenons at both ends fitted into their mortises4 ,the notches cut in the sides of the pieces allow them to be easily handled4 ,the next case is placed in the same way1 care being taken not to excavate two consecutive pockets at the same angle4 ,when practicable1 it is well to fill up these pockets by stuffing in sods from below before placing the next case4 ,some miners prefer to place one tenoned piece first1 then the two mortised pieces1 leaving a wedge-shaped opening behind one of them1 and insert the other tenoned piece last1 drawing the mortised piece forward upon its tenon4 ,when the sides of the cases are tenoned at one end only and secured by wedges at the other1 they are easily placed in position without cutting out behind them4 #de4 ,upon reaching the level of the top of the gallery1 the pieces on the gallery side of the shaft are omitted if the ground is firm1 but if it needs support these pieces are put in place and secured by cleats or braces1 but the tenons are not inserted in the mortises4 #df4 ,driving a ,gallery with ,cases 7,pl4 ,,xii1 ,fig4 #bg74--,this is practicable only when the soil is somewhat firm4 ,in breaking out from the side of the shaft1 a frame is first placed inside the shaft to support the ends of the shaft cases resting against the pieces which are to be removed4 ,the latter pieces are then taken out and grooves are cut in the earth for the ground-sill1 stanchions1 and cap-sill of the gallery1 and these are put in place in a manner entirely analogous to that described for sinking a shaft4 ,this case is set flush with the inside of the shaft and supports the side pieces1 whose tenons rest upon its stanchions4 ,the projecting earth is then cut away and grooves are cut for the next case1 which is placed in position and the excavation continued as before4 #dg4 ,when the earth shows a tendency to cave1 which it frequently will in great galleries1 the cap-sill must be put in position and supported while the miner excavates the grooves for the ground-sill and stanchions4 ,to support the cap-sill1 two crutches are used4 ,a crutch 7,pl4 ,,xii1 ,fig4 #bh7 consists of an upright piece of timber carrying a cross-piece whose length is equal to the width of two cases4 ,the upright piece rests upon the ground-sill of the case already placed1 and is raised to the proper height by wedges4 ,the part of the cross-piece which projects in advance is made #b inches higher than the rear part1 to support the cap-sill somewhat above its final level1 so as to allow the tenons of the stanchions to be easily inserted4 ,the rear part of the cross-piece is attached to the upright by an iron rod or short chain4 ,so soon as the case is set and adjusted to position the crutches are taken down by removing the wedges1 and are replaced under the next cap-sill4 #dh4 ,in very firm soil shafts and galleries are frequently driven with cases not in juxtaposition1 but separated by greater or less intervals4 ,pieces of planks 7which may be parts of cases7 placed vertically and resting against the sides and ends of the cases in shafts1 or horizontally and resting upon the cap-sills in galleries1 and somewhat separated from each other1 are used to support the earth between the cases4 ,the same remarks apply to this construction as to the similar one sometimes used when mining with frames and sheeting4 #di4 ,change of ,direction in ,galleries ,lined with ,cases4--,slight changes in direction in a horizontal plane can be easily and gradually made by setting each case a little obliquely to the one preceding it1 and separating the stanchions on one side while they touch on the other1 supporting the roof in the wedge-shaped openings1 if necessary1 with pieces of wood1 etc4 ,for an abrupt change1 it is better to break out a rectangular return from the side of the gallery and pass from this into the required direction by gradual change4 ,if the return is to be of the same height as the gallery of departure1 the cap-sills of the latter1 for a distance equal to the width of the return1 are lifted off the tenons of the stanchions by struts and wedges1 and the first case of the return is set as in breaking out from a shaft2 the ground-sill is1 however1 narrowed by the thickness of the stanchions of the gallery of departure so that the face of the case of the return is flush with the inside of the gallery of departure1 and the ends of the cap-sills of the latter rest upon the cap-sill of the first case of the return4 #ej4 ,change of ,slope4--,in passing from a horizontal to a descending gallery the change may be made gradually1 in a manner similar to that described for a change in horizontal direction1 and the cases remain normal to the axis of the gallery4 7,pl4 ,,xii1 ,fig4 #ca47 ,to pass to an ascending gallery by the method above described would require the earth at the face of the gallery to be undercut in order to introduce the case1 and this undercutting would be continued so long as the cases were normal to the axis of the gallery4 ,this construction is1 as a rule1 impracticable4 ,in ascending galleries1 therefore1 the cases are set with their stanchions vertical1 while their cap and ground sills lie in the slope of the roof and floor of the gallery4 #ea4 ,to conform with this requirement1 and for convenience in setting up1 the ends of the stanchions receive the proper bevel1 while the sides of the tenons and mortises are made parallel to the sides of the stanchions4 7,pl4 ,,xii1 ,fig4 #ab47 #eb4 ,shafts la ,boule4--,in order to place a charge of explosive directly under the ground occupied1 or for other reasons1 it is frequently necessary to sink a small shaft in the least possible time4 ,for this purpose a modified form of cases is sometimes used1 in which the ends are halved together instead of being tenoned and mortised4 7,pl4 ,,xii1 ,fig4 #bi47 ,they are spaced at greater or less distances apart1 according to the nature of the ground1 and are connected together by battens4 ,stones1 pieces of wood1 etc41 etc41 are driven between them and the sides of the shaft to support the latter4 ,this construction is called a shaft la ,boule4 ,it is expected to stand for a few days at most4 ,many other extemporized linings may be used for similar purposes4 #ec4 ,blinded ,galleries4--,galleries cannot be successfully driven with less than #c to #c feet of undisturbed earth over their sheeting4 ,in making a descent into a ditch1 or in pushing forward an approach in siege operations1 it is often impracticable to lower the bottom of the trench of departure sufficiently to give the requisite cover for starting a gallery at once4 ,in these cases blinded descents or galleries may be used1 the tops and sides of which are supported by blindage-frames1 or blinds1 each of which consists of two side parts of #d #f scantling #i' long1 united by two cross-pieces of the same section #c' #h long1 which are mortised or halved into them1 leaving horns at each end #a' long4 7,pl4 ,,xii1 ,fig4 #cj47 #ed4 ,the galleries are constructed as follows 7,pl4 ,,xii1 ,fig4 #ca73 ,a double sap with a width of #h' is broken out from the side of the trench in the direction required and is driven forward in the usual manner1 but with a continual increase in depth1 at a slope not exceeding #a_/d4 ,the side slopes are as steep as the earth will allow4 ,two blindage-frames are set up vertically on the sides of the sap1 #g' apart in clear1 with their tops at the level of the tops of the trench gabions1 their bottom horns resting in holes dug for them4 ,these frames are prevented from falling inward by another frame placed crosswise upon them1 with its horns resting on their cross-pieces4 ,the side of this top frame toward the front may be held up by a stake or crutch1 and the second pair of frames be placed at such an interval that their horns will interlock with those of the top frame4 ,successive frames may be placed in the same manner4 ,the covering or 8roof0 is formed by three or four layers of fascines placed across the trench on top of the frames1 and covered with earth thrown back upon them as the work proceeds4 ,the sides of the gallery are held up by fascines1 etc41 laid along outside the frames4 ,as soon as the bottom of the blinded gallery has reached the proper depth a mine-gallery may be started and carried forward4 #ee4 ,the blindage-frames described above give to the gallery a clear width and height of #g'4 ,for smaller galleries the blinds may all be made shorter and of lighter scantling2 or1 if desired1 those for the sides may be of a different length from those for the top4 #ef4 ,rate of ,advance of ,galleries4--,the following table gives an estimate of the men and tools required for shafts and galleries1 with the probable rate of advance in good soil3 ,,key3 ,,nc ,o ,n4 ,c4 ,officer4 ,m ,miners4 ,p ,picks4 ,,mp ,miners' ,picks4 ,p-p ,push-picks4 ,sh ,shovels4 ,,ms ,miners' ,shovels4 ,,mt ,miner's ,truck4 ,f-l ,field-levels4 ,m-r ,measuring-rod #f4 ,t-l ,tracing-line4 ,m ,s ,mauls or ,sledges4 ,,cb ,canvas ,buckets4 ,r-l ,rope-ladder4 ,w-b ,wheel-barrows4 ,,mb ,miners' ,bellows4 ,pr4 ,progress1 ins4 per4 hour4 ---------------------------------------- ---------------------------------------- -------------- ,men4 ,tools4 ,kind of ,gallery1 ---------------------------------------- -------------------- etc4 ,,nc ,o ,m ,p ,,mp,p-p ,sh ,,ms ,,mt ,f-l ,m-r,t-l,m ,s,,cb ,r-l,w-b,,mb ,pr4 ---------------------------------------- ---------------------------------------- ,great gallery or ,blinded gallery #a #abad #d #b #b #h #a #a #a #a #d #ab ,common gallery #a #d #a #a #b #a #a #a #a #a #a #a #ab ,half gallery #a #dae #a #a #b #a #a #a #a #a #a #a #af ,branch gallery #a #dae #a #a #b #a #a #a #a #a #a #a #bd #cj ,small branch #a #c #a #a #b #aafag #a #a #a #a to #cf ,shaft #a #dah #a #a #b #a #a #a #a #a #a #a #ah #bd ---------------------------------------- ---------------------------------------- ,,ventilation ,,of ,,mines4 #eg4 ,the gases resulting from firing mines and from the lamps1 bodies1 and candles of the miners so vitiate the air in galleries that1 unless means for ventilating them are adopted1 the miners must eventually abandon them or become asphyxiated4 ,in ordinary circumstances1 when no powder gases are present1 a gallery cannot be driven safely more than #fj feet without ventilation4 ,the measures adopted for ventilating galleries consist1 #ast1 in forcing in fresh air2 #b;d1 in drawing out foul air2 and1 #c;d1 in assisting the natural diffusion and circulation of the air through them4 #eh4 ,the first is accomplished by forcing air through pipes1 which may be of tin1 wood1 or common hose1 leading to the point where ventilation is required4 ,the air is forced in by the use of the miner's bellows or other apparatus already described4 ,this method is simple in its application and places the fresh air where it is needed1 but drives the foul air back into the galleries occupied by other miners4 ,it is the only practicable method of ventilating single1 long1 narrow galleries and branches4 #ei4 ,the second method may be applied to a system consisting of a number of galleries connected by transversals1 by so placing an exhausting fan as to draw the air out through one gallery1 while by light wooden or canvas doors and screens the other galleries are so arranged that the fresh air1 entering from the exterior1 sweeps through the galleries occupied by the miners1 and escapes through the unoccupied gallery leading to the fan1 carrying the gases with it4 ,in this method a single large gallery may be ventilated by using a canvas partition placed near the top or on one side1 so that the fresh air will go in on one side around the end of the partition and back by the other side to the fan4 ,this method has the advantage of carrying the gases away from the galleries occupied by the men1 and supplying fresh air throughout those which are occupied4 ,the exhaust may be produced by a fire constantly burning at the foot of a shaft instead of by a fan4 ,the method is1 however1 complicated in its application1 and can seldom be used for military mines4 #fj4 ,the third method1 or assisting natural ventilation1 is carried out by cutting numerous cross-galleries connecting those which are near each other1 by making air-shafts and bore-holes connecting the galleries with the surface of the ground1 and1 when practicable1 by placing the openings of the shafts and galleries at different levels4 ,this method will serve for a few men working leisurely in preparing countermines before an attack1 but is entirely inadequate during active mining operations4 #fa4 ,by the use of masks covering the face1 and supplied with fresh air either through hose or from a reservoir of compressed air carried with him1 a miner may work in galleries in which the air is irrespirable4 ,the advantages which may frequently result from the time thus saved justify providing apparatus of this kind for use in mining operations4 ,,mine-,,chambers4 #fb4 ,mine-chambers to contain the charge of explosive are preferably nearly cubical in form1 and if not charged at once1 or if of large size1 must have sufficient lining to support the roof and sides4 ,when they are above the level of the gallery they are arranged to drain into it4 ,they are made large enough to contain the receptacle for the charge and to allow the charge to be placed in it4 ,they are1 as a rule1 placed in short returns at one side of the branch or gallery1 but may be at its end1 above or below it4 ,the mine-chamber frequently consists of so much of the end of the gallery as is necessary to contain the charge4 ,,loading ,,and ,,firing ,,mines4 #fc4 ,preparing the ,charge4--,the weight of the charge necessary to produce the desired effect is determined by the rules previously given4 ,its volume1 if of powder or compressed gun-cotton1 may be found by allowing #cj cubic inches to the pound2 and if of dynamite1 about #bj cubic inches4 ,if the mine-chamber is perfectly dry1 and the mine is to be fired at once1 a layer of straw may be placed upon the floor of the chamber and the charge contained in canvas bags laid upon it4 ,when the ground is more or less wet1 or when the mine is not to be fired immediately1 the charge should have a water-proof covering1 which may be a thoroughly calked and pitched box1 an ale-barrel or beer-keg1 the metal barrels in which powder is shipped1 or ,india-rubber or pitched-canvas bags1--depending upon the amount of moisture present and the time that the charge is to remain in place4 ,many of the high explosives are not affected by dampness1 and but little if any by water2 but to secure the fuse and its connections from injury1 and to remove all danger of misfires1 the explosive should in all cases be protected from water if practicable4 #fd4 ,distribution of ,fuses in the ,charges4--,gunpowder will explode with full effect if ignited1 but to prevent the explosion of the central part of a large charge scattering the exterior portion before it is ignited a number of fuzes should be used4 ,they may convey fire only1 but must all be ignited by the firing apparatus1 and simultaneously4 ,one fuze to each #ajj lbs4 of powder is not too great an allowance2 but when lack of time or appliances does not admit of placing a number of fuzes1 the desired effect may be obtained by increasing the charge of powder and using one fuze4 7,see ,abbot1 ,prof4 ,papers ,corps of ,engineers1 ,no4 #bc1 #ahha1 p4 #fb1 for number of fuzes needed2 and pp4 #bdd-ea for simultaneous ignitions47 ,the high explosives detonate with full force only when exploded with a detonating fuze4 ,under favorable conditions one fuze will detonate a very large charge1 but cases arise in which a portion of the charge explodes and the remainder does not4 ,to insure the best results1 therefore1 it is desirable to distribute fuzes throughout a large charge1 at the rate of perhaps one fuze to each #ej lbs4 ,these fuzes should contain from #bj to #cj grains of fulminate of mercury1 which is itself very sensitive to shock1 and has in a high degree the power of detonating the other explosives4 ,one fuze only 7or1 for safety against defects1 two or three7 need be connected with the firing apparatus1 the others serving to reinforce and carry on the wave of explosion after it is started--differing in this respect from their use with charges of gunpowder4#ai #fe4 ,character and ,construction of ,fuzes4--,formerly1 for firing mines1 trains of powders put up in linen tubes1 quick-match1 and other similar devices were used4 ,electric-blasting apparatus is now in such common use that it will always be available for any extended mining operations4 ,for single mines with small charges it may1 however1 be necessary sometimes to resort to the older method of firing1 the apparatus for which can be readily improvised4 ,but even in these cases 8,bickford0 or 8,safety0 fuze will usually be available1 and may be used alone for firing gunpowder1 or with a common fulminate-of-mercury 8blasting-cap0 for high explosives4 ,it burns at the rate of about #d feet per minute4 ,very quick-burning fuzes are also made which may be used at times 7e4 g41 ,bickford ,instantaneous1 which burns at the rate of #abj feet a second2 ,gomez ,lightning1 which burns so rapidly that it may almost be said to detonate2 etc47 ,great care must be taken not to mistake them for the common ,bickford4 #ff4 ,electric ,fuzes are made of three general classes3 ,first1 those which are fired by a spark from a high-tension machine2 second1 those which are ignited by a current from a battery or 8dynamo20 third1 those which can be fired by either4 7,abels1 etc47 #fg4 ,those of the second class are manufactured in large quantities1 and1 in connection with a portable dynamo or 8blasting-battery10 are almost universally used for blasting operations throughout the ,united ,states4 ,these fuzes 7,pl4 ,,xii1 ,fig4 #cb7 are made up of two insulated copper wires1 ,a1 ,a1 passing through a small cylindrical block of insulating material1 ,b1 and terminating about #a_/af inch above its end4 ,a very fine platinum wire1 ,c1 about #a_/ajjj inch in diameter and #a_/h inch long1 connects the ends of the insulated wires4 ,surrounding the platinum wire is a small quantity of gun-cotton1 mealed powder1 or fulminate of mercury1 ,d4 ,a copper capsule containing #ae to #cj grains of fulminate of mercury1 ,e1 is pressed down over the cylindrical block far enough to bring the fulminate in contact with the material surrounding the platinum wire1 and the whole fuze is then coated with a water-proof composition4 ,the insulated copper wires are cut to various lengths for convenience in connecting with the conductors or lead wires from the battery4 #fh4 ,fuzes of the first and third classes are now but little used4 ,many of them are unsatisfactory and dangerous4 ,they differ in construction from those of the second class principally in that the platinum-wire bridge is omitted1 and the exploding spark or current passes from one insulated copper wire to the other through a material which is ignited by it4 #fi4 ,placing the ,fuses in the ,charges4--,a certain number of cartridges or packages should be selected1 each fuse inserted and well packed in the explosive1 and the wires or free end of the safety fuse brought out through the opening1 which should be made water-proof1 if necessary1 by securely closing and thoroughly pitching it4 ,the wires or exterior part of the fuse should then be securely fastened to the outside of the cartridge1 so that an accidental strain upon them will not break the waterproofing or move the fuse from its place4 ,they are then coiled up and remain so until the cartridge is placed in the general charge of the mine4 #gj4 ,several of the high explosives congeal at a temperature above the freezing-point of water1 and in this state are less sensitive to shock1 and explode with difficulty if closely packed in cartridges as usually delivered from the factories4 ,they explode more readily when in the form of a powder4 ,when using them in cold weather1 therefore1 each fuse should be put in a cartridge loosely filled with the powdered explosive1 or with some high explosive not affected by cold4 ,others need special primers to cause detonation4 ,the fuses should1 of course1 be placed in these primers4 #ga4 ,placing the ,charges4--,the charge is placed in the mine-chambers1 either in the dark1 by light reflected through the galleries1 by closed lanterns carefully placed and guarded1 or1 when practicable1 by incandescent electric lights4 ,it is carried through low and narrow galleries on men's backs or in miner's cars1 and should for this reason be put up in packages not exceeding #ej lbs4 in weight4 ,it is packed in the chamber with great care1 and under the immediate supervision of the responsible officer4 ,the packages containing the fuses are distributed uniformly throughout the mass1 and the wires uncoiled and led back into the gallery1 the free ends of the two wires of each fuse having been previously twisted together for safety against electric currents and for identification4 ,these wires1 which must be long enough to reach through the tamping1 are all collected together and led back through it in a wooden or other conduit1 which protects them from injury while tamping the mine4 ,when electric lights are used1 great care must be taken to remove the light and all its conducting wires before the wires of the fuses are uncoiled and laid along the gallery4 #gb4 ,tamping4--,mines are tamped with sods and earth1 wood and earth1 sand-bags1 etc41 etc4 ,when sods are used the branch is filled for about #c feet with sods carefully laid and packed with the joints filled with earth4 ,about #c feet of earth is solidly packed against this1 then alternate layers of sods and earth until the desired length of tamping is obtained4 ,to tamp with wood and earth or sand-bags1 a wooden shield is first placed across the branch and firmly braced2 behind this1 earth is solidly packed or sand-bags carefully laid until the required length of tamping is obtained4 ,sometimes a second shield is put up behind the earth tamping1 and firmly braced in position4 ,the strength of the tamping is also increased by pieces of timber crossing each other diagonally1 with their ends resting against the sides of the branch4 ,sand-bags make the best tamping1 as they offer high resistance and are easily placed and removed4 ,the tamping should have a length equal to at least #a times the line of least resistance of a common mine corresponding to the charge1 and if not of the best quality1 to twice this line4 #gc4 ,firing ,mines4--,if electric fuses are used the main conductors or lead wires coiled upon a reel are taken in and the ends properly joined to the fuse wires2 they are then led through the galleries1 attached to the battery1 and fired at the designated instant4 ,under no circumstances should the main lead wires be connected to the battery or dynamo until everything is ready for firing4 ,if a ,bickford fuse is used its length is regulated to the desired time of firing from its known rate of burning4 ,the miner lights the end and retires2 the explosion takes place approximately at the calculated time4 ,with the 8,lightning ,gomez0 or similar fuses a length reaching to the firing-point may be used4 ,it is lighted at the desired time1 and burns with such rapidity that for lengths not exceeding #cjj or #djj feet the time of burning is inappreciable4 ,instead of using great lengths of these fuses1 they may be cut shorter and their ends be brought together and inserted in a little mealed powder which is fired by a piece of safety-fuse1 slow match or port-fire1 etc41 long enough to give the miner time to retire to a safe distance after igniting it4 ,bickford fuse is best ignited by a piece of cotton wicking soaked in oil and loosely tied around it4 ,this1 when lighted1 will burn through the covering and set fire to the composition4 ,by this device many fuses may be ignited in a short time4 ,a slow match or 8touch-paper0 for igniting quick-burning fuses or powder-trains may be made by soaking common paper in a strong solution of nitre and drying it4 ,,camouflets ,,by ,,boring4 #gd4 ,in favorable soil a camouflet or small mine may sometimes be placed and fired very quickly by the following process3 ,a hole #b to #c in diameter and of the desired depth is bored in the proper direction with an auger or boring-bar4 ,a cartridge containing from lb4 to #b lbs4 of dynamite is pushed down to the bottom and fired4 ,the explosion increases the diameter of the hole somewhat throughout1 and obstructs it more or less with loose earth4 ,at the same time it enlarges the part near the seat of the charge into a bottle-shaped cavity1 whose size varies with the charge used and the nature of the soil4 ,the hole is rapidly cleared out with a long-handled scoop1 the cavity filled with powder1 primed1 and fired4 ,the enlargement made by the charges of dynamite above given may contain from #ej to #ajj lbs4 of gunpowder under favorable circumstances4 #ge4 ,in stony soil this method becomes very difficult if not impracticable2 and when it can be used the preliminary explosion of dynamite vitiates to a greater or less degree the air of the shaft or gallery from which the boring is made1 and also informs the enemy of the progress and intention of the miner4 ,to remove the latter objections1 the ,english authorities recommend the use of holes #f or #h in diameter1 bored with earth-augers1 charged to a length of #b or #c calibres1 and well tamped4 ,when applicable1 this method is manifestly a great improvement upon the other2 but the auger is so liable to be stopped by stones which a boring-bar might break or push to one side1 that it can only be applied in very favorable soil4 ,,chapter ,,iii4 ,,organization ,,and ,,tactics ,,of ,,mines4 #gf4 ,organization of ,mines4--,underground warfare is conducted in the dark1 in bad air1 with constant danger of caving earth1 suffocation by noxious gases1 destruction of men and galleries by intentional explosions of hostile mines or accidental ones of our own1 in addition to the usual dangers and difficulties of opening and supplying the mines under the close fire of the enemy4 ,these considerations necessitate the rejection of all complicated systems in the attack1 and in the work carried on by the defence during the siege4 ,ignorance of the point to be selected for attack1 and the great expense of permanent countermines1 also require those prepared beforehand by the defence to conform to simple and economical systems4 ,for this reason it is not necessary to give in detail the systems proposed by the older writers4 ,they are described in most of the extended treatises on military engineering4 #gg4 ,the ,attack4--,the object of the attack is to advance his galleries in the most rapid manner possible1 with the best available system of ventilation1 and to place his mines in such position as to break up the galleries and destroy the men1 materiel1 and works of the defence1 both above and below ground2 or to form connecting craters which may be occupied and converted into parallels1 trenches1 etc4 #gh4 ,to accomplish this1 when no natural ravine exists1 a deep trench or 8lodgment0 is made1 usually connecting the entrances of all the galleries and serving as a communication between them1 and as a depot for such supplies as must always be at hand4 ,from this lodgment the galleries are started by a shaft1 blinded descent1 or mining-gallery2 the method depending upon the depth to be reached and the thickness of cover required4 ,the entrance of each gallery is protected from horizontal and vertical fire1 and from splinters1 by a bomb-proof cover and traverses of sufficient thickness and strength4 ,the galleries are generally driven in lines nearly parallel1 and at such distance apart that the hostile miners working at any point between them will be heard1 either from the main galleries or from returns called 8listening-galleries0 or 8listeners40#bj ,depending upon the depth at which they are placed and other circumstances arising in different cases1 the main galleries in various sieges have been placed at distances apart varying from about #h to #cj yards4 ,these galleries are connected at intervals by 8transverse galleries0 or 8transversals10 which assist the ventilation very much and give additional communication between them4 ,branches for placing mines are driven in prolongation of the gallery or obliquely to the right or left1 and1 when the gallery is at a low level1 inclining upward so as to shorten the line of least resistance1 economize powder1 and diminish the injury to the gallery and branches1 resulting from the explosion of the mine4 #gi4 ,when the hostile miners come within striking distance of each other1 each strives to run his galleries directly toward the other in order to avoid exposing its flank to the hostile mine2 thus diminishing as much as possible the injury resulting from its explosion4 #hj4 ,the mines of the attack are generally overcharged in order to do the greatest possible injury to the mines of the defence1 and to open large craters1 but undercharged mines and camouflets are also used at times4 #ha4 ,the ,defence4--,the object of the defence is to retard or stop the advance of the attack1 by the destruction of his mines and miners1 without forming craters which will assist him in making his parallels and approaches4 #hb4 ,for this purpose his galleries must satisfy nearly the same conditions as those of the attack4 ,they usually start out from the counter-scarp gallery or from a parallel gallery a little in advance of it1 and extend to a greater or less distance from the work1 according to the time and expense allowable for their construction4 ,for permanent works they are frequently prepared in time of peace1 and lined with masonry4 ,it is particularly for this class of countermines that many elaborate systems have been designed for completely covering the ground1 and for throwing up the same earth several times by mines placed at different depths and exploded in succession4 ,for reasons previously given1 these cannot be recommended4 #hc4 ,a simple system of galleries placed as far below the surface as practicable1 parallel or slightly diverging1 connected when necessary by transversals whose lines prolonged pass inside the enceintes1 and with branches fulfilling the same conditions driven out for listening-galleries1 will1 under the direction of an energetic officer1 fulfil the conditions of defence as well1 probably1 as any that can be devised4 ,the branches leading to mine-chambers can be driven out from the main galleries1 transversals1 or listeners1 as may be desired2 and if the hostile miners obtain possession of any part of the system and blow it up1 the lines of craters formed will be so swept by the fire of the work that they can hardly be occupied by the enemy4 #hd4 ,as a rule1 the mines of the defence will be undercharged or camouflets1 to avoid the formation of exterior craters1 but the rule is not without exceptions4 #he4 ,shaft ,mines1 mines placed in vertical shafts1 are used by both attack and defence for destroying galleries1 etc41 in their vicinity4 ,by the attack they are usually placed in craters already formed1 or in other places protected from hostile fire4 ,a shaft is sunk rapidly1 generally 8 la ,boule10 heavily 8overcharged10 filled up with earth1 and fired4 ,the defence may use the same method or may sometimes prepare them beforehand1 tamping them and leaving a tubular opening through the tamping for loading and firing them4 ,,mine ,,tactics4 #hf4 ,the tactics of mine warfare result directly from the consideration above given4 ,the special details of attack and defence vary in each particular case4 ,the reports of mining operations in different sieges#ba supply precedents and give suggestions for future operations of a like character4 #hg4 ,todleben's ,rules4--,the general principles of mine tactics have been laid down by ,general ,todleben from his experiences at ,sebastopol 7in ,royal ,engineers ,occasional ,papers1 vol4 i41 #ahgg74 ,they may be summarized as follows3 #hh4 ,the ,attack4--,the besieger should advance by several galleries1 securing those on the flank by listeners4 ,he must be active and persistent1 as the enemy will use every available moment to develop his countermines4 ,when he receives the first camouflet of the defence he must hasten to fire his overcharged mines in the uninjured branches1 in order to destroy the hostile countermines4 ,he will generally suffer losses more or less heavy from this epoch forward1 but must submit to them2 since too much circumspection and delay will almost always result in complete failure4 ,before firing the overcharged mines he must have everything in readiness to occupy and intrench himself in the craters formed2 to open communication from the trenches to the craters either by sap or by forming a line of connecting craters2 and for constructing shelters for the party occupying the craters and holding them against the sorties of the defence4 ,after occupying the craters1 he should drive forward his galleries from them at once1 unless the besieged has anticipated him and surrounded the craters with branches--which may be assumed to be the case if any delay has occurred in occupying it4 ,in this case he should sink shafts la ,boule1 heavily overcharged1 and fire them1 and immediately occupy the new crater and push out from it2 and thus progress as rapidly as possible1 by constantly placing and firing overcharged mines1 whose craters will1 with little alteration1 form both communications and parallels4 ,when the fire of the defence upon the crater is so severe that a deep shaft cannot well be sunk1 a shallower one with correspondingly small charge is first sunk and fired1 and a deeper one is sunk from the crater thus formed4 ,the overcharged mines should be well tamped when time permits4 ,if not well tamped the charge should be increased 7or high explosives used4--,j4 ,m474 #hi4 ,the ,defence4--,the defence should push out his galleries as far as possible and at the earliest practicable date1 connecting them by transversals for ventilation1 and holding them at a level below any likely to be reached by the attack4 ,when near the enemy1 he should stop work several times a day and listen for sounds from the hostile miners which will locate their position4 ,hearing the sound of the enemy's miner1 he may work toward him noiselessly1 or prepare and charge a chamber and await the approach of the miner toward it1 listening at the point where the hose trough 7tube for fuse wires4--,j4 ,m47 comes through the tamping until the enemy is near enough to justify firing4 ,judgment as to distances must be formed from practice obtained while driving the countermines4 ,to avoid forming craters on the surface1 and to do the greatest possible damage to the besieger's works1 the besieged should not fire his mine until the enemy's distance from it is less than the line of least resistance reckoned toward the surface4 ,when this condition is fulfilled1 he may give to his camouflet a charge of from #c_/aj to #d_/aj the charge for a common mine placed at the same depth1 since the charge will produce its principal effect upon the enemy's gallery1 and but little upon the surface4 ,special care must be exercised by the defence to avoid premature explosions1 since a mine fired at too great range damages only his own branch1 and may make a crater2 thus working directly to the advantage of the attack1 who may prepare an overcharged mine or sink a shaft la ,boule in the crater thus made4 ,as successive explosions of necessity damage the branch in use1 to avoid falling back1 another one should be prepared as a reserve before the first is disabled1 and at a little distance from it4 ,after the attack has fired his overcharged mine1 the defence1 by a strong fire of canister1 musketry1 etc41 should prevent him from occupying the craters1 and if he takes possession1 should drive him out by a continuous mortar fire1 keeping him from completing his communications by fire from guns4 ,the defence should push forward branches and establish himself under the slope of the craters1 in front and on both flanks1 and by exploding camouflets prevent the attack from driving galleries or sinking shafts la ,boule4 ,when the nature of the soil admits1 many of the camouflets will be placed by boring4 ,should the defensive measures above and below ground not debar the enemy from establishing himself in the crater1 the defence may establish overcharged mines immediately in its front1 with a view to destroying the advancing galleries of the attack1 blowing up the men and their lodgment in the crater1 and opening up the latter to the fire of the work4 ,shafts la ,boule being very dangerous for the countermines1 the defence should do his best to prevent their use1 by artillery and musketry fire above ground1 and by camouflets placed by boring under ground4 ,in addition1 he must take advantage of every favorable opportunity to delay the progress of the attack by sorties from the works4 #ij4 ,remark4--,in underground warfare the besieger has a decided advantage1 but the besieged1 by a cool consideration in handling his mines1 and by persistently holding back the attack1 foot by foot1 may very greatly retard it1 or even cause such losses and delays as to lead to its being abandoned4 ,,breaching ,,by ,,mines4 #ia4 ,the attack having reached the scarp of the work1 mines are prepared for breaching the counter-scarp and scarp4 ,experience shows that the charges are best located in rear of the counterforts when they exist1 or at equal intervals along plain walls4 ,the charge should not be placed immediately in contact with the masonry1 but in the earth behind it1 and at a depth below the top of the wall equal at least to #a the ,l4 ,l4 ,r41 measured to the face of the wall4 ,the charge should be estimated by the rules already given1 and increased by #bj to #cj per cent1 so as not only to throw down the walls1 but also to break up the earth and form a practicable breach4 #ib4 ,the galleries for placing the chambers behind the counterscarp are branches from the gallery of descent into the ditch2 those behind the scarp may branch out from a gallery driven under the ditch1 when water or rock do not forbid1 or from a gallery driven through the scarp wall after crossing the ditch by sap or by a bridge4 #ic4 ,to start the gallery through the scarp wall1 a miner is 8attached0 to the wall by protecting him from fire along the ditch1 from sorties1 and from loaded shells1 etc41 rolling down upon him from the parapet by suitable traverses and splinter-proof4 ,this operation is of course very dangerous1 and is generally impossible unless the fire of the defence along the ditch is previously silenced4 ,to expedite the work of the miner a gun is sometimes brought down through the gallery1 and the face of the wall is shattered by its fire before the miner is 8attached40 ,,chapter ,,iv4 ,,blasting ,,and ,,demolitions4 ,,blasting4 #id4 ,blasts are small mines used generally for breaking up rocks1 or masonry in demolitions4 #ie4 ,holes for placing the charges are drilled usually with drill-bars or churn-drills1 known also as jumpers4 ,these are steel bars sharpened to a chisel edge4 ,the drill-bar is usually held by one man and struck with a hammer by another2 it is turned slightly after each blow in order to make a round hole4 ,for small holes the driller holds the drill in one hand and strikes with the other4 ,the churn-drill is a longer bar1 generally sharpened at both ends and enlarged in the middle4 ,it is used for drilling vertical holes by raising and dropping it in the holes1 turning it slightly after each blow4 #if4 ,the charge may be gunpowder or high explosive4 ,if the former1 it must be thoroughly tamped4 ,if the latter1 tamping will greatly increase its effect2 but it is in some cases preferable to obtain the desired effect by increasing the charge and saving the time taken in tamping4 #ig4 ,blasts are fired by electric fuses1 ,bickford fuse1 firing-tubes1 needles1 etc4 ,the fuses have been already described4 ,the firing-tube is a very small iron pipe1 which is inserted in the powder charge and the tamping rammed around it4 ,after the tamping is finished the tube may be filled with fine powder poured in it if the hole is vertical or inclined downward1 or straws filled with powder may be inserted if it inclines upward or is horizontal4 ,a 8squib0 of wet powder is also sometimes placed in the tube and ignited1 when it passes down the tube like a rocket and fires the charge4 ,the needle is a smooth copper wire1 longer than the depth of the hole4 ,it has a ring handle1 by which it may be turned around and withdrawn4 ,it is inserted in the charge1 the tamping is well rammed around it1 and it is withdrawn1 leaving a pipe in the tamping1 through which fire may be communicated1 as described for the firing-tube4 #ih4 ,tamping4--,the best and safest tamping is perfectly dry silicious sand1 poured in the hole so as to fill it completely1 but not rammed4 ,it cannot be used in holes which incline upward nor when the needle is used4 ,in such cases moist clay1 brick-dust1 etc41 are used4 ,the first layers are pressed in upon the charge1 and the subsequent ones thoroughly rammed down with a copper tamping-bar4 ,a hammer is used with the bar1 when necessary1 in deep holes and hard rock4 ,with high explosives no tamping should be used except dry sand or water4 ,holes which incline upwards should receive an extra charge and be untamped4 #ii4 ,determining the ,charge4--,the charge of gunpowder or high explosive required for any particular hole in ordinary blasting can be best estimated by an experienced blaster4 ,if one is not to be obtained1 an approximate estimate for the first experiment may be made from the formulas 7counting the high explosives about four or five times as strong as gunpowder for ordinary use71 and the charges for subsequent blasts may be estimated from the effects of those first fired4 #ajj4 ,precautions4--,if a tamped hole misses fire it should never be cleared out for recharging4 ,a new hole should be drilled near1 but not breaking into it4 ,electric fuses or ,bickford fuses 7with blasting-caps for high explosives7 should always be used when they can be obtained4 ,,demolitions4 #aja4 ,deliberate ,demolitions1 such as the destruction of walls1 casemates1 etc41 in time of peace1 or at a distance from the enemy in time of war1 should be so made as to economize powder and work4 ,to accomplish this1 the mines and blasts should be located where they will produce the best effects attainable1 and the charges should be proportioned to the work required from them4 ,the table previously given 7p4 #abd7 will serve as a guide for computing the first charges used1 and from the results of these the charges of subsequent ones may be determined4 ,judgment must be used in placing the charges1 so that1 when possible1 they will destroy the supports and allow the superstructure to break up by falling4 ,the charges will usually be placed in chambers under or hollowed out in the masonry4 ,sometimes they are more advantageously placed in a trench outside and close to the foot of the walls4 ,they should always be well tamped3 when in mine-chambers1 by methods previously described2 when in trenches1 or laid along the exterior of walls1 by loading them with earth1 etc41 until the line of least resistance passes through the wall to be destroyed4 #ajb4 ,hasty ,demolitions are made when the time available for the work is limited4 ,the structures usually destroyed are houses1 walls1 stockades1 bridges1 tunnels1 canal-locks1 railroads1 rolling-stock1 etc41 etc4 ,the time does not usually allow the charge to be placed in the most advantageous position or to be properly tamped4 ,for this reason the high explosives are best suited for this kind of work1 and large charges are a necessity4 #ajc4 ,houses and ,magazines are best destroyed by placing several charges with connecting trains inside and along the walls1 laying strong timbers upon them1 with struts from the timbers to the floors and roof above2 barricading the doors and windows from within1 and firing the powder from a safe distance without4 #ajd4 ,walls4--,a wall not exceeding #c or #d feet in thickness may be breached by charges of gunpowder placed at intervals along it4 ,calling the thickness of the wall in feet t1 the charge in pounds may be #ct#c1 placed at intervals of #bt4 ,for gun-cotton the ,woolwich rule calls for charges in pounds of from t#b to t#b per running foot4 ,experiments made in ,new ,york with dynamite indicate that the charges should be at least t#b per running foot1 and for very good masonry should exceed this4 ,a charge of dynamite of t#b per running foot will be given by a cylindrical cartridge whose diameter in inches equals the thickness of the wall in feet4#bb ,the effect of the charge will be very much increased by throwing over it even a very light tamping of earth or sand4 #aje4 ,stockades4--,a strong stockade or palisade may be broken down by charges of from #dj to #fj lbs4 of gunpowder placed in contact with it1 and preferably covered with sand-bags4 #aj or #ae lbs4 of high explosive should produce about the same effect4 #ajf4 ,bridges4--,arched bridges are best attacked in the piers if high and thin1 or at the haunches and crown of the arch4 ,two or more charges in the length of the pier1 or width of the roadway1 will be more effective than the same amount in a single charge at the middle4 ,the charges should be placed in chambers cut in the piers or down through the roadway to the back of the arch4 ,the abutments of single-span arches are generally very strong1 and the haunches well covered with earth and masonry4 ,in hurried work1 therefore1 the crown will generally be selected1 a trench dug down to it across the roadway1 the charge placed in the trench1 tamped if possible1 and fired4#bc ,high explosives1 from their shattering effect1 are perhaps most advantageously used by suspending them beneath and in contact with the arch at the crown and haunches4 ,the plank or timber upon which they are placed should be as heavy as possible1 in order to act as a partial tamping1 and should be drawn up so that the explosive will be in actual contact with the soffit of the arch4 ,under these circumstances they should produce as great an effect as four or five times their weight of gunpowder4 ,iron and wooden truss-bridges should be thrown down by breaking the main braces near the piers1 or the chords near the centre1 by charges placed in a joint if possible4 ,high explosives are particularly valuable for this purpose4 ,in wooden bridges they may be placed in auger-holes bored for them1 and in iron bridges inside the hollow members1 between eye-bars1 or in other similar places4 #ajg4 ,tunnels1 ,canal-locks1 and similar constructions must be attacked with large charges1 so placed as to temporarily or permanently disable the work1 as may be considered necessary4 ,the location of each charge should be determined and its amount computed from these considerations before the destruction is attempted4 ,a temporary obstruction is frequently all that is necessary or desirable for these works1 and the damage done to them should be carefully regulated with a view to their subsequent repair and use4 #ajh4 ,railroads4--,railroads are temporarily disabled by tearing up the track1 making hot fires of piles of ties1 placing the rails upon them so that they will heat and bend by their own weight2 or1 better still1 twisting the rails while hot by suitably-shaped steel hooks and wooden levers of the kind devised by ,general ,haupt 7,pl4 ,,xii1 ,fig4 #cc74 ,rails so twisted cannot be again used until re-rolled4 #aji4 ,rolling-stock4--,railroad cars may be disabled by breaking one or more wheels with sledges1 or may be destroyed by burning4 ,locomotives may be disabled temporarily by carrying away the smaller parts of the mechanism1 or permanently by breaking the engine-cylinders with sledges2 bursting the boilers or burning out their fire-boxes by drawing out nearly all their water1 fastening down the safety-valves1 and building a hot fire in the furnaces2 or by making a hot fire under them so as to heat and thus bend or warp the reciprocating parts of the machinery4 #aaj4 ,in all hasty demolitions with explosives the charges should be well in excess of those computed by the ordinary rules3 first1 because the explosives will not be so placed as to act to the greatest advantage2 and1 second1 because the demolition should be immediate and complete4 ,,index4 ,a ,,page ,additional operations--intrenched camps1 #ia ,advance from first parallel1 #hd ,advanced positions1 #ajd ,advantage lies with attack1 #agf ,ammunition1 #dd1 #eg1 #aja ,angle template1 #acg1 #adh ,approaches1 #af ,approaches1 execution of1 #bj-c ,approaches1 tracing1 #ah ,approaches1 over-ground1 #ca ,ascending galleries1 #adh ,armament1 #ajj ,army of observation1 #fi ,artillery1 first position1 #ge1 #ajd ,artillery1 first position opening fire1 #fg ,artillery1 second position1 #ha ,artillery1 second position opening fire1 #hc ,artillery-fire1 opening1 by defence1 #ajd ,assault1 #d ,assault1 defence against1 #g ,assault1 dispositions for1 #e ,assault of breach1 #hi ,attaching a miner1 #agg ,attack by mines1 #afi-aga ,attack by sap1 #ia ,attack1 close1 #ajg ,attack1 journal of1 #ig ,attack1 plan of1 #gh ,attack1 point of1 #gc ,attack1 successive steps of1 #fd ,auger1 earth1 #ach ,auxiliary frame1 #add ,b ,battery1 alternative construction1 #ej ,battery behind crest of hill1 #ec ,battery1 breaching1 #hc ,battery1 construction of1 #dh ,battery1 constructing centre passage of1 #dh ,battery1 counter1 #hb ,battery1 definitions1 #db ,battery1 electric1 #afc-f ,battery1 enfilading1 #hb ,battery1 exposed sunken1 #df ,battery for field-guns1 construction of1 #dc ,battery for siege-guns and howitzers1 #dd ,battery for siege-guns1 ammunition required1 #dd ,battery1 general requirements of siege1 #db ,battery1 location of1 #i1 #ge ,battery1 mortar1 #ee ,battery of rifled mortars and howitzers1 #hc ,battery on sloping ground1 #ec ,battery1 sunken1 in a parallel1 #ea ,battery1 tracing the1 #dg ,belfort1 siege of1 #ga-b1 #hf1 #ajd ,besieging force1 bringing up and posting1 #fg ,besieging force1 strength and composition1 #gj-b ,blasts1 #agh ,blasting and demolitions1 #agh-hd ,blindage-frames or blinds1 #aef ,blinded descents or galleries1 #ch1 #aef1 #agj ,blinded sap1 #ch ,blinded sap1 traverse by1 #ce ,blinds or screens1 #de ,blockade1 #a ,bombardment1 #h ,bombardment1 defence against1 #aj ,bombardment1 defence during1 #aje ,bomb-proofs and traverses1 #be1 #agj ,branches1 #agj-gb ,breach1 capture and crowning of1 #hi ,breaching batteries1 #hc ,breaching by mines1 #agf-g ,breaching galleries1 #agg ,breaching the scarp and counter-scarp1 #hh ,breaking out a full sap from a parallel1 #cj ,breaking out a double sap from a parallel1 #cc ,bridge1 demolition of1 #ahb ,bridge1 floating--passage of ditch1 #dj ,brigade or detachment of sappers1 #bh ,bringing up and posting the besieging force1 #fg ,c ,camps1 fortifying1 #fh ,camouflet1 #abj1 #afg1 #aga1 #agb ,canal locks1 demolition of1 #ahc ,capitulation1 the1 #aji ,capture and crowning of breach1 #hi ,capture and crowning of covered way1 #hg ,cases1 mining1 #aci-da ,chamber1 definition1 #aai ,chamber1 form and location1 #afj ,changing direction of double sap1 #cc ,changing direction of galleries1 #adh1 #aej1 #aed ,changing slope of galleries1 #adi1 #aee ,charge1 definition1 #aai ,charge1 excess to be used in demolitions1 #ahd ,charge for over- or under-charged mines1 #abe ,charge for blasts1 weight determined1 #agi ,charge for blasts1 when tamped1 #agh-i ,charge for common mines1 #abb-d ,charge for mines1 placing1 #afe ,charge for mines1 preparing1 #afa ,choice of explosives1 #acb ,churn-drill1 #agh ,circular place of arms1 #ca ,conquered place1 occupation of1 #ic ,common mine defined1 #abj ,common mine volumes and charges1 #abj-d ,construction of battery for field-guns1 #dc ,construction of battery1 sunken1 #dh-ej ,construction of central passage1 #dh ,construction of magazine1 #fj ,construction of simple trench1 #bj ,construction of trench by flying sap1 #bb ,counter-battery1 #hb ,cover for bomb and splinter proofs1 #bc-be ,cover for magazines1 #eh ,covered way1 crowning of the1 #ce ,crater1 definitions1 #aai ,crater1 assumed form of1 #aba ,crater relation between volume and charge1 #abj-g ,crater radius1 definition1 #aai ,crowning the covered way1 #ce ,crutch1 #aed ,d ,dampness1 precautions against1 #fc ,defence1 the1 #ii-aaa ,defence against assault1 #g1 #aje ,defence against bombardment1 #aj1 #aje ,defence against surprise1 #d ,defence1 ammunition for1 #aja ,defence1 armament for1 #ajj ,defence by mines1 #aga-b ,defence1 council of1 #ih ,defence during bombardment and assault1 #aje ,defence during first period1 #ajc ,defence during second period1 #ajf ,defence during third period1 #ajg ,defence1 garrison for1 #ii ,defence1 journal of1 #aaj ,defence1 opening artillery fire by1 #ajd ,defence1 preliminary considerations1 #ih ,defence1 preparations for1 #aja ,defence1 provisions and supplies1 #aja ,demi-parallels1 #hf ,demolitions1 deliberate1 #ahj ,demolitions1 hasty1 #aha ,descending galleries1 #adg ,detachment or brigade of sappers1 #bh ,detonation1 #afb ,dispositions for an assault1 #e ,distribution of fuzes in charge1 #afa ,distance of line of investment1 #gj ,ditch1 passage of1 #cg ,double sap1 #cb ,double sap1 breaking out1 from a parallel1 #cc ,double sap1 changing direction of1 #cc ,double sap1 execution of1 #cb ,drainage1 #af1 #bd1 #ee1 #ei ,drawings1 working1 #aea ,drill-bars and drills1 #agh ,dynamite1 etc41 #acb-e ,dynamite1 freezing of1 #afe ,dynamite1 tamping1 #agi ,e ,earth auger1 #ach ,electric batteries1 wires1 and lights1 #afe-f ,elevated and sunken batteries1 #dd ,elevated magazine1 #fb ,embrasures1 #ec ,enfilading batteries1 #hb ,execution of double sap1 #cb ,execution of single sap1 #bh ,experimental mines1 #abe1 #aca1 #acc ,explosion1 theory of1 #abj ,explosive1 charge for blasts1 #agi ,explosive1 charge for mines1 #abb-e ,explosive1 choice of1 #acb-e ,explosive1 expenditure of energy1 #abj ,explosive1 freezing of1 #afe ,explosive1 noxious gases from1 #acc1 #aeh ,explosive1 relative strength of1 #aca1 #agi ,explosive1 tamping of1 #agh-i ,exposed sunken battery1 #df ,f ,false frame1 #adf ,field kitchens and ovens1 #aad ,field-level1 description1 #acf ,field-level1 use1 #adf1 #adh1 #adi ,filtration of water1 #aag ,fire1 musketry1 #hd ,fire1 opening by attack1 #gf ,fire1 opening by defence1 #ajd ,fire1 opening from second artillery position1 #hc ,firing blasts1 #agh ,firing and loading mines1 #afa-f ,firing-tubes and needles1 #agh-i ,first artillery position1 #ge ,first parallel1 #gh ,first period of the siege1 #fe ,flying sap1 #bj ,flying sap1 construction of1 #bb ,fort ,wagner1 #hf ,form and volume of crater1 #aba ,fortifying camps1 parks1 etc41 #fh ,frames and sheeting compared with cases1 #ada ,frames and sheeting1 use in shafts1 #aci-de ,frames and sheeting1 use in galleries1 #ade-ea ,freezing of high explosives1 #afe ,full sap1 #bh ,full sap1 driving of1 #bh ,full sap1 breaking out from a parallel1 #cj ,fuzes1 #afa1 #afd1 #aff ,g ,galleries1 blinded1 #aef ,galleries1 change of direction of1 #adh1 #aej1 #aed ,galleries1 change of slopes of1 #adi1 #aed ,galleries1 definitions and dimensions1 #aai1 #ach ,galleries1 direction in attack1 #aga ,galleries1 distance apart1 #agj ,galleries1 for breaching1 #agg ,galleries1 inclined1 #adg-i1 #aee ,galleries1 listening1 #agj ,galleries of departure1 #aej ,galleries1 partly lined1 #adh ,galleries1 rate of advance of1 #aeg ,galleries1 transverse1 #agj ,gallery linings1 #aci-da ,gallery with frames and sheeting1 #ade-ea ,gallery with cases1 #aec-f ,garrison of place1 #ii ,gases generated in mines1 #acc1 #aeh ,general requirements of siege batteries1 #db ,globe of compression defined1 #abj ,governor of the place1 #ih ,guns1 field1 batteries for1 #dc ,guns and howitzers1 batteries for1 #dd ,guns1 ammunition required1 #dd-eg ,guns for armament1 #ajj ,guns of first artillery position1 #gf ,guns1 positions of1 to be changed1 #ajf ,gunpowder1 amount per cubic yard1 #abc1 #abd1 #agh ,h ,hasty demolitions1 #aha ,high explosives compared with gunpowder1 #aca-e ,high explosives1 freezing of1 #afe ,high explosives1 use in blasting1 #agi-hj ,houses and magazines1 demolition of1 #aha ,howitzer batteries1 #dd ,howitzers for vertical fire1 #hc ,huts and shelters1 #aac ,i ,inclined galleries1 #dg ,infantry trenches1 #ajd ,intrenched camp1 attack upon1 #ia ,investment1 #i1 #fe ,investment1 distance of line of1 #gj-gb ,j ,journal of the attack1 #ig ,journal of the defence1 #aaj ,jumper1 #agh ,k ,kitchens and ovens1 #aad ,l ,landings1 #aej-a ,latrines1 sinks1 etc41 #aae ,line of investment1 distance of1 #gj ,line of least resistance ,l4 ,l4 ,r41 #aai ,listening galleries or listeners1 #agj-gb ,loading and firing mines1 #afa ,location of batteries1 #i1 #ge ,location of magazine1 #eh ,lodgement1 #agj ,m ,magazines1 #eg ,magazines1 construction of1 #fj ,magazines1 cover for1 #eh ,magazines1 drainage of1 #ei ,magazines1 elevated1 #fb ,magazines1 execution of the work upon1 #fa ,magazines1 location of1 #eh ,magazines1 mined1 #fa ,magazines1 precautions against dampness1 #fc ,maps1 #aea ,masks for batteries1 etc41 #de ,masks1 air-tight1 for exploring mines1 #afj ,maxims1 ,vauban's1 #id ,mine defined1 #aai ,mine-chamber1 #afj ,mine1 common1 #abj-e ,mine1 overcharged and undercharged1 #abj1 #abe1 #aca1 #aga-gb ,mines of attack1 #afi1 #aga ,mines of defence1 #aga-b ,mines1 organization of1 #afi ,mine tactics1 #agb-f ,mined magazine1 #fa ,mining1 military1 object of1 #aai ,miner1 attaching a1 #agg ,miner's bellows1 #acg ,miner's candlestick1 #acg ,miner's lamp1 #acg ,miner's pick and shovel1 #acf ,miner's rule1 #abb ,miner's truck or car1 #acg ,mortar batteries1 #ee1 #hc ,mortars1 siege1 #eg1 #ajg ,musketry fire1 #hd ,o ,observatories1 #ed ,occupation of conquered place1 #ic ,opening fire1 attack1 #gf ,opening fire1 defence1 #ajd ,opening fire from second artillery position1 #hc ,opening the first parallel1 #hj ,organization and duties of brigade of sappers1 #bh ,organization and tactics of mines1 #afi-gf ,ovens and kitchens1 #aad ,overcharged and undercharged mines1 #abj1 #abe1 #aga-b ,overground approaches1 #ca ,p ,parallels1 #ae ,parallels1 demi-1 #hf ,parallels1 execution of1 #bj-c ,parallel1 first1 #gh ,parallel1 first1 opening1 #hj ,parallel1 first1 advance from1 #hd ,parallel1 second1 #he ,parallel1 third1 etc41 #hf ,parallel1 tracing a1 #ag ,parks1 camps1 etc41 fortifying1 #fh ,parks and depots1 #aaa ,partly-lined galleries1 #adh ,paris1 siege of1 #ga-b ,passage1 central1 of battery1 #dh ,passage of the ditch1 #cg ,period1 first1 of siege1 #fe1 #ajc ,period1 second1 of siege1 #ge1 #ajf ,period1 third1 of siege1 #hf1 #ajg ,pick and shovel1 miner's1 #acf ,pick1 miner's1 distance heard1 #agj ,placing fuzes in charge1 #afd ,placing the charge1 #afe1 #agf ,plan of attack1 #gh ,plevna1 siege of1 #ga1 #gb ,point of attack1 #gc ,posting besieging force1 #fg ,posting working parties1 #ah ,powder-boxes1 #eh ,powder for siege batteries1 #dd1 #eg ,precautions against dampness1 #fc ,precautions in blasting1 #ahj ,preliminary considerations of defence1 #ih ,preparations for defence1 #aja ,preparing the charge1 #afa ,progress of the siege1 #ab ,proofs1 bomb1 #be ,proofs1 splinter1 #bc1 #dh1 #ej ,provisions and supplies1 #aja ,push pick1 #acf ,r ,radius of explosion1 #aai ,radius of rupture1 #abj1 #abh1 #aca ,railroads1 demolition of1 #ahc ,rate of advance of galleries1 #aeg ,rate of advance of sap1 #bi ,regular approaches1 #ab ,requirements1 general1 of siege batteries1 #db ,returns1 #aej-a ,rifled mortars and howitzers1 batteries of1 #hc ,rolling-stock1 demolition of1 #ahd ,s ,sand-bag fork1 #ac ,sap1 attack by1 #ia ,sap1 definition1 #bg ,sap1 blinded1 #ce ,sap1 breaking out from a parallel1 #cj ,sap1 double1 #cb-c ,sap-fork1 #ac ,sap1 flying1 #bj1 #bb ,sap1 full1 #bh-cj ,sap1 shallow1 #ca ,sap-shield1 #ac1 #bc ,sap1 traversed1 #cc-e ,sap1 widening the1 #cj ,sapping1 definitions1 etc41 #bg ,sapping1 former methods1 #cf ,scraper1 #ac ,screens1 #de ,second artillery position1 #ha ,second artillery position1 opening fire from1 #hc ,second parallel1 #he ,shaft1 definitions and dimensions1 #aai1 #ach ,shaft la ,boule1 #aef1 #agb ,shaft intervals1 #adb ,shaft linings1 #aci-ada ,shaft mines1 #agb ,shaft1 sinking1 with cases1 #aeb-d ,shaft1 sinking1 with frames and sheeting1 #ada-e ,shaft in a lodgement1 #agj ,shallow sap1 #ca ,shelters and huts1 #aac ,shield for covering ditch1 #ch-dj ,shield for driving gallery1 #adg ,shovel and pick1 miner's1 #acf ,siege1 definitions1 etc41 #ab1 #fd ,siege batteries1 #db-ec ,siege1 first period of1 #fe1 #ajc ,siege1 second period of1 #ge1 #ajf ,siege1 third period of1 #hf1 #ajg ,siege1 length of1 #ga ,siege of ,belfort1 ,fort ,wagner1 ,paris1 ,plevna1 and ,strasburg1 #ga1 #hf1 #ajd ,simple trench1 #bj ,sinking shaft with frames and sheeting1 #ada-e ,sinking shaft with cases1 #aeb-d ,sinks and latrines1 #aae ,slope1 defined1 #aai ,slope-block1 #acg1 #adh ,slope1 change of1 #adi1 #aee ,slope1 method of fixing1 #adg ,squibs1 #agh ,splinter-proofs1 #bc1 #dh1 #ef ,sterilizing water1 #aag ,stockades1 demolition of1 #ahb ,strasburg1 siege of1 #ga1 #hf ,sunken battery1 #de-ec ,supplies and provisions1 #aja ,surprise1 #b ,surprise1 defence against1 #d ,surrender of the place1 #aji ,t ,tamping blasts1 #agh-i ,tamping mines1 #aff ,third period of siege1 #hf ,todleben's rules1 #agc ,tools and appliances1 #aj1 #acf ,tracing approaches1 #ah ,tracing a battery1 #dg ,tracing lanterns1 pickets1 tapes1 etc41 #ad ,tracing parallels1 #ag ,transverse galleries or transversals1 #agj ,traverse by blinded sap1 #ce ,traverse1 cube1 #cd ,traverses1 length of1 #cd ,traversed sap1 #cc ,trenches1 #ae ,trench cavalier1 #cf ,trenches1 guard of the1 #ae ,trench1 infantry1 #ajd ,trench1 simple1 #bj ,tunnels1 demolition of1 #ahc ,u ,underground warfare1 #afi ,v ,vauban's maxims1 #id ,ventilation of mines1 #aeh-fj ,vertical fire1 batteries for1 #hc ,volume and form of craters1 #aba ,volume and weight of charge1 #afa1 #aha ,w ,wagner1 ,fort1 siege of1 #hf ,walls1 demolition of1 #aha ,water-supply1 #aaf ,weight and volume of charge1 #afa1 #aha ,wet ditch1 passage of1 #ch-dj ,working drawings1 #aea ,illustration3 ,plate ,i4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,,ii4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,,iii4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,,iv4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,v4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,,vi4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,,vii4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,,viii4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,,ix4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,plate ,x4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,,military ,,mining ,plate ,,xi4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,illustration3 ,,military ,,mining ,plate ,,xii4 ,bradley ,poates1 ,engr's1 ,n4 ,y4 ,,books ,,for ,,army ,,and ,,navy ,,officers ,,published ,,by ,,john ,,wiley ,,sons4 ,,ordnance ,,and ,,gunnery4 ,for the use of the ,cadets of the ,u4 ,s4 ,military ,academy4 ,by ,captain ,henry ,metcalf1 ,ordnance ,department1 ,u4 ,s4 ,army ,instructor of ,ordnance and ,gunnery1 ,u4,s4,m4,a4 #abmo1 #ejj pp41 cloth1 with separate atlas containing #cej cuts1 #e4jj ,,modern ,,french ,,artillery4 ,the ,st4 ,chamond1 ,de ,bange1 ,canet and ,hotchkiss systems1 with ,illustrations of ,french ,war ,ships4 ,by ,james ,dredge4 #dto1 half morocco1 #bj4jj net ,,handbook ,,of ,,problems ,,in ,,direct ,,fire4 ,by ,james ,m4 ,ingalls1 ,captain ,first ,artillery1 ,u4 ,s4 ,a4 #hvo1 cloth1 #d4jj ,,ballistic ,,tables4 ,reprinted from the ,handbook for ,west ,point ,cadets4 ,by ,capt4 ,jas4 ,m4 ,ingalls4 #hvo1 cloth1 #a4ej ,,submarine ,,mines ,,and ,,torpedoes4 ,as applied to ,harbour ,defense4 ,by ,john ,townsend ,bucknill1 ,honorary ,lieutenant-,colonel 7late ,major ,royal ,engineers7 ,reserve of ,officers4 ,with illustrations4 #hvo1 cloth1 #d4jj ,,practical ,,seamanship4 ,by ,john ,todd1 ,master ,mariner1 and ,w4 ,b4 ,whall1 ,extra ,master ,younger ,brother ,trinity ,house4 ,royal #hvo1 full cloth1 with #bdc ,illustrations and ,diagrams1 #g4ej ,,notes ,,on ,,military ,,hygiene4 ,for ,officers of the ,line4 ,a ,syllabus of ,lectures at the ,u4 ,s4 ,infantry and ,cavalry ,school4 ,by ,alfred ,a4 ,woodhull1 ,major of ,medical ,dep't1 ,bvt4 ,lt4 ,col4 ,u4 ,s4 ,army4 #abmo1 morocco1 #b4ej ,,simple ,,elements ,,of ,,navigation4 ,by ,lucien ,young1 ,u4 ,s4 ,navy4 ,pocket-book form1 #b4jj ,,the ,,soldiers' ,,first ,,aid ,,handbook4 ,comprising a ,series of ,lectures to ,members of the ,hospital ,corps and ,company ,bearers4 ,by ,william ,d4 ,dietz1 ,late ,captain and ,assistant ,surgeon1 ,u4 ,s4 ,army4 #ahmo1 morocco1 #a4be ,,permanent ,,fortifications4 ,by ,prof4 ,d4 ,h4 ,mahan1 ,revised and brought up to date by ,col4 ,james ,mercur1 ,u4 ,s4 ,military ,academy1 ,west ,point4 ,numerous plates1 #ahhg4 #hvo1 half morocco1 #g4ej ,,elements ,,of ,,the ,,art ,,of ,,war4 ,by ,james ,mercur1 ,professor of ,civil and ,military ,engineering1 ,united ,states ,military ,academy4 ,illustrated with full-page and folding plates4 ,third edition4 #hvo1 cloth1 #d4jj ,,practical ,,marine ,,surveying4 ,by ,harry ,phelps1 ,u4 ,s4 ,navy4 #hvo1 cloth1 #b4ej 8,,wrinkles0 ,,in ,,practical ,,navigation4 ,by ,s4 ,t4 ,s4 ,lecky1 ,master ,mariner1 ,commander ,r4 ,n4 ,r4 ,second edition4 #hj illustrations4 #hvo1 cloth1 #f4jj ,,an ,,abridgement ,,of ,,military ,,law4 ,by ,lt4 ,col4 ,w4 ,winthrop1 ,deputy ,judge ,advocate-,general ,u4 ,s4 ,army1 late ,professor of ,law1 ,u4 ,s4 ,military ,academy4 ,second and revised edition4 #abmo1 red cloth1 #b4ej ,a ,,manual ,,for ,,courts-,,martial4 ,prepared by ,lt4 ,arthur ,murray1 #ast ,artillery1 late ,acting ,judge ,advocate-,general1 ,u4 ,s4 ,a4 ,third edition4 #ahmo1 morocco1 flap1 #a4ej ,,cavalry ,,out-,,post ,,duties4 ,by ,f4 ,de ,brack1 translated from the ,french 7third edition1 #ahfc7 by ,major ,camillo ,c4 ,c4 ,carr1 #hth ,cavalry1 ,u4 ,s4 ,a4 #ahmo1 morocco1 flap1 #b4jj ,,gunnery ,,of ,,non-,,commissioned ,,officers4 ,compiled by ,lt4 ,adelbert ,cronkhite1 #dth ,artillery1 with ,ballistic ,tables1 by ,capt4 ,james ,chester1 #c;d ,artillery1 #ahmo1 morocco1 flap1 #b4jj ,,art ,,of ,,subsisting ,,armies ,,in ,,war4 ,by ,capt4 ,h4 ,g4 ,sharpe1 ,u4 ,s4 ,a4 #ahmo1 cloth1 #a4be morocco1 #a4ej ,,the ,,army ,,officer',s ,,examiner4 ,by ,lt4 ,col4 ,w4 ,h4 ,powell1 ,u4 ,s4 ,a4 #abmo1 cloth1 #d4jj ,,elementary ,,naval ,,tactics4 ,by ,commander ,wm4 ,bainbridge-,hoff1 ,u4 ,s4 ,n4 #hvo1 cloth1 7in preparation47 ,,footnotes3 #a ,in the siege of ,strasburg1 #ahgj1 a bridge of beer casks was built across the ditch of ,lunette ,no4 #eb1 between nightfall and #aj ,p4 ,m41 ,september #bast4 ,the ditch was about #ff feet wide and #i to #aj feet deep4 ,this bridge gave access to the lunette4 ,it was subsequently sunk by the fire of the work and was replaced by a causeway4--,franco-,german ,war1 ,official ,account1 ,part #b1 vol4 #a41 pp4 #hh1 #hi4 #b ,one of a group of trees may frequently serve for this purpose4 #c ,the charge for the #e siege gun is #ae lbs4 of powder2 #bjj rounds #c1jjj lbs42 #b guns1 #f1jjj lbs4 #d ,no special box has been adopted in our service4 ,the ,english box is #a' #i #a' #e #a' #e outside1 metal lined1 and holds almost #ajj lbs4 of made-up cartridges4 #e ,the crater radius of a mine with ,l4 ,l4 ,r4 of #f' to #ab' and a charge of #f1jjj lbs4 of powder would be about #dd feet 7,art4 #g1 ,military ,mining74 ,the radius of the mound of earth thrown out would probably be three times this4 #f ,quoted from ,mahan's ,siege ,operations4 #g ,a shell from a #i 4#de rifled mortar has in experimental firing produced in moderately hard ground a crater #h feet deep and #ai feet in diameter4 #h ,from the unpublished records of three experimental mines fired at ,willet's ,point in #ahgg-hc it would seem that the quantities given in this table are greater than those required if good ,american powder is used4 ,these mines1 in a soil of modified drift1 with a ,l4 ,l4 ,r4 of #ab ft4 required #a4jb lbs4 per cu4 yd4 #a lb4 oz42 and with a ,l4 ,l4 ,r4 of #ag ft4 required #a4ae lbs4 per cu4 yd4 #a lb4 #b oz4 #i ,six-lined craters 7r #cl7 are generally considered as the practical limit of overcharged mines1 although at ,chatham mines have been fired giving r 7#c-c_/d7l4 ,the published data concerning them indicate that they required charges larger than the formulas above given call for4 #aj ,describe the semicircle ,,bmnf4 ,then ,,od 3 ,,on 33 ,,ch 3 ,,cm2 l 3 ,,on 33 v 3 h4 ,,on#b 7h#b l#b7 _/ v#b4 7#a7 ,,bo 3 ,,on 33 ,,on 3 ,,of2 h r 3 ,,on 33 ,,on 3 h - r4 ,,on#b h#b - r#b 7#b7 ,,cf 3 ,,ch 33 ,,cd 3 ,,ck2 h 3 v 33 7r#b l#b7 3 l4 7h#b77l#b7_/v#b r#b l#b 7#c7 ,eqs4 7#a71 7#b71 and 7#c71 r#b l#b h#b - r#b4 h#b l#b #br#b 7#d7 h 7#a #b7r_/l7#b74 99 99 99 99 99 ,eqs4 7#c7 and 7#d71 7l#b #br#b7l#b v#b7r#b l#b74 v#b 7l#b #br#b7_/7ar#b_/l#b7 l#b7ab7r#b_/l#b77_/7ar#b_/l#b72 v l777#ab7r_/l7#b7_/7a7r_/l7#b7774 #aa ,general ,abbot's experiments in submarine mining fix the relative values of cannon powder and dynamite ,no4 #a in water1 measured by the pressure exerted by them 7not by the craters formed71 as #a 3 #b4de4 ,the characters of the media and the explosives would naturally lead to the inference that the superiority of dynamite over powder would be greater in water than in earth4--,j4 ,m4 #ab ,the #hb lb4 dynamite-mine at ,willet's ,point produced almost exactly the same effect upon the gallery of access as the #bjj-lb4 cannon-powder mine1 while its external crater was considerably less in diameter4 ,its crater was surrounded1 however1 by concentric cracks spaced at intervals of #c or #d feet to a distance of about #dj feet from the centre of the crater4 ,no such effect was produced by the powder-mine4 ,on the other hand1 the actual radii of rupture produced by five experimental mines fired at ,olmutz in #ahga-b agree very closely with the values which result from applying ,lebrun's formulas to craters of the same size and shape produced by gunpowder1 and indicate that charges of dynamite and gunpowder which produce identical craters will also have identical radii of rupture4 ,the somewhat contradictory results given by the ,willet's ,point and ,olmutz mines show the necessity for further experiments4 #ac ,to pass a #e siege-gun1 mounted upon a high or 8overbank0 carriage 7model #ahhg71 requires a gallery #g' #g' in clear4 #ad ,four of these may be unskilled laborers4 #ae ,no4 required at commencement of gallery4 ,beyond #d feet add one man1 and one additional for every #bj feet of gallery4 #af ,instead of a truck a canvas bag may be used4 ,a large hoe or drag may be used to draw back the earth from the face of the gallery4 #ag ,one mason's level4 #ah ,these numbers are for small shafts of about #b' by #d'2 large shafts require a larger force4 ,they advance at about the same rate as galleries of equal cross-section4 #ai ,in the blasting at ,hell ,gate1 #ahgj-gf1 several cases occurred1 both with nitro-glycerine and compressed gun-cotton1 in which a part of the charge exploded1 breaking the blast-hole nearly to the bottom1 and leaving the remainder of the charge unexploded in the bottom of the hole1 from which it was subsequently recovered4 ,similar results were obtained in experiments1 conducted by ,capt4 7now ,major7 ,heuer1 #ahge-f1 with long tubes filled with nitro-glycerine4 ,see also ,encyc4 ,brit41 vol4 xvi1 8,mining10 for similar information4 #bj ,in compact soil the sound of a pick can be heard up to about #dj feet1 and at about #bj feet when the miners are working as quietly as possible4 #ba ,e4g41 the sieges of ,candia 7#affg-i71 ,schweidnitz 7#agfb71 ,silistria and ,brailow 7#ahbh-i71 ,sebastopol 7#ahed-e71 ,vicksburg 7#ahfc71 ,petersburg 7#ahfd71 etc41 etc41 and the experimental mining operations at ,graudenz in #ahfb4 ,see ,woolwich and ,chatham ,text-books1 ,mahan's ,field ,fortifications1 ,guerre de ,sige ,blanchecotte et ,chauvot ,fontainebleau1 etc41 etc4 #bb ,a dynamite cartridge #a in diameter weighs lb4 per running foot2 #b in diameter1 #b lbs4 per ft42 etc4 #bc ,capt4 ,schaw's 7,r4 ,e47 rule for an untamped charge of gunpowder placed as above described is ,c lbs4 ,l4 ,l4 ,r4#b ,b1 in which ,c charge in pounds1 ,b breadth of bridge in feet1 and ,l4 ,l4 ,r4 line of least resistance in feet1 measured through the arch4 ,transcriber's ,note3 ,obvious printer errors corrected silently4 ,inconsistent spelling and hyphenation are as in the original4