,illustration3 ,a ,,sub-,,surface ,,irrigation ,,sewage-,,disposal ,,plant4 ,sewage4 ,frontispiece4 ,practical ,methods of ,sewage ,disposal ,,for ,,residences1 ,,hotels ,,and ,,institutions ,,by ,,henry ,n4 ,,ogden ,m4 ,,am4 ,,soc4 ,c4,e4 ,professor of ,sanitary ,engineering1 ,cornell ,university ,,and ,h4 ,,burdett ,,cleveland ,,assoc4 ,m4 ,,am4 ,,soc4 ,c4,e4 ,principal ,assistant ,engineer1 ,new ,york ,state ,department of ,health ,,first ,,edition ,,first ,,thousand ,,new ,,york ,,john ,,wiley ,,sons ,,london3 ,,chapman ,,hall1 ,,limited #aiab ,copyright1 #aiab1 by ,,henry ,n4 ,,ogden and ,h4 ,,burdett ,,cleveland ,,publishers ,,printing ,,co41 #dai-dba ,,lafayette ,,st1 ,,new ,,york ---------------------------------------- -------------------------------- ,,contents ,,chapter ,i4 ,,introductory ,,pages ,the problem of sewage disposal4 ,composition and character of #a-ac sewage4 ,action of bacteria4 ,soils and their value for sewage treatment4 ,three essential conditions for effective sewage purification4 ,rates of operation4 ,preliminary and final treatment4 ,,chapter ,,ii4 ,,the ,,settling ,,tank ,function and capacity of settling tanks4 ,their construction4 #ad-cf ,siphon chambers4 ,use of concrete4 ,pipe connections4 ,roof4 ,baffle boards4 ,imhoff or ,emscher tanks4 ,,chapter ,,iii4 ,,valves1 ,,siphons1 ,,and ,,siphon ,,chambers ,hand valves4 ,gate valves4 ,flap valves4 ,various types of #cg-ed siphons4 ,alternating and plural siphons4 ,air-lock siphons4 ,dosing apparatus4 ,,chapter ,,iv4 ,,sub-,,surface ,,irrigation ,advantages of sub-surface irrigation for sewage disposal4 #ee-gb ,details of system4 ,tables for use in constructing4 ,siphon chambers4 ,sub-surface tile4 ,alternate use of separate portions of area4 ,underdrainage4 ,,chapter ,v4 ,,sewage ,,filters ,relative efficiency of various types4 ,sand ,filters4 ,tables for #gc-ig use in constructing siphons4 ,dosing and distribution methods4 ,maintenance4 ,contact ,beds4 ,methods of construction4 ,alternate and timed siphons for filling and discharging4 ,table for use in constructing4 ,sprinkling ,filters4 ,their construction and operation4 ,complicated and undesirable for small installation4 ,,chapter ,,vi4 ,,broad ,,irrigation ,fertilizing elements in sewage4 ,value of sewage for irrigation4 #ih-aaa ,area required for sewage irrigation4 ,methods of applying the sewage4 ,maintenance of irrigated areas4 ,,chapter ,,vii4 ,,estimates ,,of ,,cost ,cost of material3 of laying sewers and drains2 of sand2 of #aab-abh excavating and refilling2 of rock excavation2 of concrete work2 of valves2 of dosing devices2 of filling material for beds2 of finishing and cleaning up4 ,table to show items to be considered in estimate of cost4 ,,list ,,of ,,figures ,a sub-surface irrigation sewage-disposal plant ,frontispiece ,,figure ,,page #a4 ,plan of settling tank #ae #b4 ,longitudinal section of settling tank #ag #c4 ,sketch of settling tank with longitudinal #ai partition wall #d4 ,forms used for building side walls for concrete #bc tank #e4 ,view of settling tank1 showing baffles1 sludge #bf pipe1 drain pipe1 and inlet and outlet pipes #f4 ,section showing tank with concrete roof and form #bh for constructing roof #g4 ,form for manhole opening #cj #h4 ,plan and longitudinal section of modified ,imhoff #cc tank #i4 ,vertical cross-section of modified ,imhoff tank #cd #aj4 ,sludge valve for floor of tank #ch #aa4 ,sludge valve for side wall of tank #ci #ab4 ,sluice gate valve made by ,coffin ,valve ,co #dj #ac4 ,ordinary gate valve #dj #ad4 ,english slide valve with wedge-lock handle #da #ae4 ,flap valve attached to length of sewer pipe #db #af4 ,flap valve with metallic seat attached #dc #ag4 ,flap valve with loose-link hinges #dd #ah4 ,intermittent dosing apparatus made by ,ansonia #de ,manufacturing ,co4 #ai4 ,simplest form of automatic siphon #df #bj4 ,van ,vranken automatic siphon #dg #ba4 ,miller automatic siphon #dh #bb4 ,double alternating siphons of the 8,merritt0 type #di #bc4 ,triple alternating siphons of the ,miller type #ej #bd4 ,single 8,merritt0 automatic siphon #ea #be4 ,air-lock siphon for admitting and releasing #eb sewage from each one of four beds in regular order #bf4 ,plan and section of sub-surface irrigation system #fa #bg4 ,plan and section of a portion of a sub-surface #fb irrigation system #bh4 ,y-branch of vitrified tile pipe #fd #bi4 ,eighth bend of vitrified tile pipe #fd #cj4 ,sub-surface tiling #fe #ca4 ,photograph of tile laid as if for sewage disposal #ff #cb4 ,sub-surface tiling with broken stone or gravel #fg surrounding pipe #cc4 ,sub-surface systems on irregular ground #fh #cd4 ,special casting of double ,y-branch with swinging #fi gate #ce4 ,double ,y-branch with valves on branches of main #gj carrier #cf4 ,sub-surface tiling system with underdrains #ga #cg4 ,view of sand-filter beds for village in #ge ,massachusetts #ch4 ,layout for intermittent sand filtration #gh #ci4 ,intermittent sand-filtration beds #gi #dj4 ,portion of distributing troughs for sand filters #hj #da4 ,general view of disposal plant at ,bedford #ha ,reformatory #db4 ,view of sand filter with distribution trough4 #hb ,settling tank is at the end of the bed #dc4 ,view of diverting manhole #hc #dd4 ,plan of diverting manhole #hd #de4 ,five-way diverting manhole #he #df4 ,general plans of contact-bed system near ,albany1 #hi ,n4 ,y41 opposite page #dg4 ,view of sprinkling filter at ,dansville1 ,pa41 in #ie winter #dh4 ,distribution of sewage and arrangement of check #ajf levees on a hillside #di4 ,distribution of sewage on a hillside of moderate #ajg slope #ej4 ,square beds for orchards according to some #ajh ,western practice #ea4 ,grain-field in spring in process of irrigation #aji ,,practical ,,methods ,,of ,,sewage ,,disposal ,,for ,,residences1 ,,hotels ,,and ,,institutions ,,chapter ,i ,,introductory ,the problem of sewage disposal for a single house differs from the corresponding problem for a city chiefly in two ways3 first1 because in the city it is becoming1 if it has not1 indeed1 already become1 a necessity1 and city authorities1 though somewhat reluctantly1 are willing to grant the necessary appropriation to secure engineering advice which will solve the problem in a scientific as well as economic fashion4 ,in the case of a single house1 whether a farm-house or a villa1 the necessity of employing competent engineering advice has not been generally recognized1 and no attempt has been made to solve the problem of sewage disposal in a scientific manner4 ,cesspools have been considered the only way of caring for sewage in places where a running stream was not available1 or where attempts were made to protect such a stream from pollution1 and while1 in these last few years1 crude attempts have been made to utilize the so-called septic tank1 such attempts have generally been so unintelligent that the results have been anything but satisfactory4 ,since it has been understood that insects1 such as flies and mosquitoes1 play an important part in the transmission of disease1 the danger of overflowing cesspools and of open ditches in which stagnant sewage is present1 has been appreciated2 also the higher standards of living which have made themselves felt throughout the rural community have demanded in farm-houses and country homes sanitary conveniences which have hitherto been wanting4 ,gradually every house is using more and more water for various purposes1 and living conditions1 which in the past tolerated a scanty supply drawn from a pump1 are no longer endured4 ,the increased water supply and the demands of extended plumbing mean a greater amount of sewage--so great an amount that1 in many cases1 soils which could receive and digest the waste waters from houses supplied by wells are clogged and made impervious by this greater amount4 ,further1 the danger to wells from the infiltration of cesspools is more feared1 and it is understood as never before that in order to maintain the highest degree of health in a family the drinking-water used must be above suspicion and not subject to contaminating influences in the vicinity4 ,again1 communities are being aroused to the intrinsic value of maintaining streams in a pure condition--partly because of the value of fish and ice coming from the streams themselves1 and partly on the broad ground that watercourses belong to the country as a whole1 and must be kept pure for the sake of succeeding generations1 not spoiled for them on account of the selfishness of a few at the present time4 ,thus it is that to-day the problem of sewage disposal1 while arousing general interest1 is recognized as one which requires more than the common sense of an average person1 that the force and principles involved are understood to be not those in common use1 and that1 for successful disposal of sewage1 special knowledge and judgment are required4 ,whatever the character of the sewage and whatever the kind of soil available for treatment1 the method of dealing with sewage most obvious to most people has been to discharge the sewage directly into the nearest watercourse4 ,this has been the practice of cities as well as of individual houses in the past1 and the practice is very difficult to check because of the economy of this method of disposal4 ,in many cases there is no objection to this method1 and where a large stream is available1 where no use is made further downstream of the waters for drinking purposes1 and where the volume of water in the stream is sufficient to dilute the sewage to a point where no odors or objectionable appearances result1 it would seem most uneconomical to adopt any more complicated method of disposal than by simply carrying the outfall pipe into the main bed of the stream4 ,in ,new ,york ,state1 and in a number of other ,states1 the number of which is continually increasing1 such direct discharge1 however1 is not permitted by law except under certain conditions4 ,in ,new ,york ,state it is required that any house1 butter or cheese factory1 manufacturing establishment1 or village shall obtain the permission of the ,state ,commissioner of ,health before such a method of discharge be adopted1 and in order to obtain this permission it must be definitely shown that the conditions of the stream are such that no reasonable objection to this method could be urged4 ,the policy of the various ,departments of ,health in the ,united ,states is gradually becoming more and more rigorous in the matter of prohibiting the discharge of crude sewage into watercourses1 and it is wise to make very sure that the discharge of sewage into streams is above the suspicion of a nuisance before adopting this as a suitable method4 ,rather would it seem better to provide for some method of treatment and allow only purified sewage to go into the stream than to run the risk of being forced in a few years to reconstruct the entire line of outfall pipe1 with perhaps an entire reconstruction of the plumbing within the house4 ,the problem of treatment is the question of so modifying the character of a large volume of dirty water that it shall neither injure the quality of any drinking-water into which it may be discharged1 nor cause objectionable odors1 nor present disagreeable appearances in any body of water into which it may be emptied4 ,in order to properly understand a reasonable method of treatment some consideration must be given to the composition of sewage4 ,this is chiefly water with which is mixed a small amount of animal1 vegetable1 and mineral matter4 ,roughly speaking1 the amount of mineral dirt is about one tablespoonful to a barrelful of water1 and the combined amount of animal and vegetable matter amounts to another tablespoonful4 ,it seems almost impossible that so small a quantity of organic matter as one tablespoonful in a barrel of water could cause offense in any way1 and yet engineers1 city officials1 and householders know by bitter experience that1 when spread out on the surface of the ground or when allowed to stand in pools1 water so polluted will undergo putrefaction resulting in most disagreeable odors and in complete stagnation4 ,the problem of sewage treatment1 then1 consists in removing from the barrelful of water1 the tablespoonful of organic dirt1 whether animal or vegetable1 in such a way that no odors shall be occasioned by the process and at the same time so that the cost of the process may be a reasonable one4 ,unfortunately1 the greater part of this organic matter is in solution1 dissolved1 like salt in water1 so that1 though undeniably present1 it must be removed by some process more complicated and less obvious than that of simple straining4 ,it would be comparatively simple if the polluting substances remained floating or suspended in the water4 ,then they could be strained out through a fine sieve or settled out in a tank1 either with or without the aid of chemicals4 ,but for particles in solution1 straining1 by itself1 is useless and1 while in large plants frequent use is made of sieves as a complement to the main process of purification1 in small plants it is of so little value as hardly to deserve consideration4 ,another factor enters to lessen the value of the use of screens or sieves in an installation for a single house4 ,a great deal of the organic matter found in sewers requires both agitation and time for its subdivision into particles small enough to be acted upon in any process of purification adopted4 ,if a screen is used1 large particles of putrescible matter are held on the screen since not enough time has existed to break down their mass1 and thus the screen itself becomes a most emphatic disturbance and a most objectionable feature of the purification plant4 ,for efficient purification1 therefore1 some method of reducing and modifying the character of organic solids1 particularly those in solution1 must be selected4 ,in seeking a method by which this may be accomplished1 scientific men found years ago that this very process was being carried on continually by natural forces1 although at a very slow rate of purification4 ,all organic matter1 however formed and wherever present1 is subject to the natural forces of decay4 ,fruits1 vegetables1 and meats of all kinds1 exposed to the air1 rapidly lose their original character and form and in the course of time disappear entirely4 ,except for this provision of nature1 the accumulation of organic wastes since the beginning of the earth's occupation by human beings would be so great that the earth would be uninhabitable on account of the deposits of waste matter which would have formed by this time4 ,nature1 then1 recognizes the need of disposing of organic wastes1 and her method is the one which apparently must be followed by human beings if successful treatment is to be secured4 ,only a few decades ago1 it was found that this process of decay was due to the activity of very small organisms known as bacteria1 and their agency was proved by experiments which showed that if vegetables or meat were kept free from bacteria1 no decay1 fermentation1 or putrefaction took place4 ,it was proved that the air itself was not responsible because in certain experiments air was allowed to enter through a filtering medium fine enough to strain out the bacteria and no decay took place1 although oxygen and air were both freely admitted4 ,it is well understood by the housewife that fruits can be kept indefinitely if they are cooked sufficiently to kill any bacteria present and then sealed in bacteria-free1 air-tight jars4 ,when such preserves spoil1 it is because some bacteria were left in the jar or have since been admitted through an imperfect top4 ,when decay is allowed to proceed1 the obvious result is1 first of all1 a softening of the material1 as in the case of a rotten apple1 a liquefaction1 as it is more technically known4 ,following that part of the process is a gradual breaking down of the material1 the residue being of an earthy character which is assimilated by the soil into which it falls4 ,the bacteria required for the putrefaction of organic matter are among the most widely distributed of all the micro-organisms4 ,they are always found in the air1 except on mountain tops1 in deserts1 and over the ocean4 ,they are very numerous in surface waters1 such as streams and ponds1 and their relative number everywhere increases as the amount of organic matter increases1 so that the greater the need for them the greater is their number4 ,it has been found that the great majority of these bacteria require air for their energetic development1 and this fact is most important when it comes to the practical construction of a piece of apparatus for making use of these bacteria4 ,it has also been found that1 for several reasons1 these bacteria work most effectively in the soil and can take care of a larger quantity of organic matter there than elsewhere4 ,this is partly because in the surface layers of the soil1 particularly where that soil has been cultivated1 a great number of the particular bacteria involved in decay are always to be found4 ,pure1 clean sand from the desert contains almost none of these beneficent bacteria4 ,rich garden soil is fairly teeming with them1 so that1 curiously1 the more organic matter and the more bacteria present in any soil1 the more active that soil will be in taking care of other organic matter4 ,then1 again1 the soil particles1 particularly in sandy soil1 are so separated as to allow between them a certain and appreciable amount of air1 and by means of this air the activity of the bacteria is made continuous and the products of their activity utilized4 ,without such an admission of air1 the bacteria are choked and diminish rapidly in numbers4 ,there is1 however1 a definite degree of purification and a certain quantity of organic matter which can be taken care of by the bacteria incident to any particular soil4 ,up to that quantity purification proceeds more or less satisfactorily according to the intelligence shown in feeding the bacteria in such a way as suits their convenience4 ,if1 however1 that quantity be exceeded1 all purification stops1 the bacteria are apparently discouraged1 and no further improvements can be expected4 ,a fine-grained soil will not be so useful as a coarse-grained soil because the former does not allow sufficient air in the interstices of its soil particles4 ,another practical reason for not making use of soils of fine grains is that such soils can absorb only a small amount of liquid because of the mechanical construction of the material4 ,on the other hand1 soils whose grains are too coarse are undesirable because their mechanical construction is such that the liquids containing organic matter in solution pass through so rapidly that time enough is not given for bacterial action4 ,as a result of the principles just enumerated1 it may be said that there are three distinct and essential conditions for the successful disposal of sewage through the soil4 ,these three conditions are1 first1 a rate of application suitable to the soil which it is proposed to use2 second1 an interrupted or intermittent delivery of the sewage so that the bacteria can obtain1 between consecutive doses of sewage1 the necessary amount of oxygen for their own preservation and well-being2 and1 third1 a resting period in which is carried forward that intimate association between the partly decomposed organic matter and the oxygen or air present in the pores of the soil by which the final oxidation is obtained4 ,the rate of application varies1 as already indicated1 with the size of particles found in the soil1 and it should also vary with the purification desired4 ,the larger the particles1 the higher may be the rate of application1 but less efficient will be the process4 ,with grains of sand as fine as #a_/bjj of an inch1 and with a rate of application not greater than five gallons per square yard of surface per day1 filtration through such an area has been proved to be capable of removing from the foulest sewage all the objectionable material and converting the liquid into what is an equivalent of the purest spring water4 ,if the rate appropriate to this particular soil is exceeded1 the efficiency decreases1 and the unmistakable and inevitable result is to stop all purification and convert the filter into a stagnant cesspool4 ,if1 to take the other extreme1 the soil particles are increased until they are as large as hen's eggs1 then1 if the rate of application is not greater than #bjj gallons per square yard of surface per day1 and if the method and rate of application are suitable to this large amount1 the resulting effluent is sufficiently freed from its objectionable matter so that the liquid can be turned into any body of water without danger of odors or other nuisance4 ,if this rate is exceeded1 or if the method of application is not carefully considered1 the resulting effluent is foul in the extreme and the process itself becomes a nuisance4 ,it can be seen by this brief explanation that it is not possible to assign any particular rate of application to any particular kind of treatment1 since in all the methods of purification which have been worked out considerable variation in the details of that particular method have been practised4 ,it will be possible1 therefore1 in succeeding chapters to indicate by the size of filters recommended only limiting or average values for rates of purification1 since those rates are always dependent upon other factors than the particular method being discussed4 ,it must also be remembered that soils may exist which have no porosity whatever1 and through which it is impossible for sewage to make its way4 ,such soils are not available for sewage purification1 and1 no matter how small the rate or how careful the method of application1 such areas will fail to produce any practical purification4 ,soils like clay1 peat1 and fine water-deposited silt are of this sort4 ,clay soils may sometimes become pulverized by cultivation so that they will ultimately be able to take care of a moderate amount of sewage4 ,in such a case it is possible to dispose of sewage successfully in the top six inches of soil which1 by continual cultivation1 has been made out of the stiff clay4 ,in such cases1 the difficulty is not that of oxidizing the sewage1 but that of taking care of the effluent1 which must be held between the cultivated soil and the raw clay underneath4 ,the second requirement mentioned is secured by discharging the sewage onto the soil area at intervals1 the number of doses per day depending upon the size of particles in the bed4 ,there has been a general principle established that the size of these doses ought to be smaller as the size of the particles increases1 so that1 whereas in the case of sand beds the total daily dose is usually divided into from one to three parts and each part delivered onto the bed with an appropriate interval1 in the case of coarser materials used for sprinkling filters1 the time interval between doses is much reduced and in some installations recently constructed in ,england that interval has been measured in seconds4 ,the variations in the rate of flow of sewage onto any filter1 however1 are so great that any such requirement as designing discharging apparatus to work at intervals of a few seconds is useless1 and if as small an interval as one minute is provided for the coarsest material for the maximum rate of flow at any time of the day1 the installation will probably be successful for the lesser rates occurring at other times of the day4 ,as an indication of the way in which this modification is made1 it is customary1 when the size of soil particles is that of peas1 to make the interval between successive discharges about one hour1 so that the dose applied at any one time would be equal to #a_/bd of the daily volume4 ,with gravel filling1 the particles being the size of ,english walnuts1 the interval between doses is shortened to five minutes1 and the amount of any one dose is thus made #a about #a_/bhj of the total daily volume4 ,with the coarser filling1 as when a size as large as hen's eggs is used1 the interval would be cut down to about one minute4 ,it should be added that the intervals last mentioned are characteristic only of some devices used for dosing sprinkling filters and that there is a wide divergence of practice among engineers when dealing with any particular size of sand or stone particles in all kinds of filter beds4 ,the third requirement1 namely1 the occasional resting of the bed1 is met by providing some additional area over that theoretically required1 so that the flow may be diverted from part to part of the total area 7which is usually divided into beds for this purpose71 and in this way each part is allowed1 in turn1 a period for resting4 ,for example1 if the required area be divided into two beds and a third bed added equal in area to one of the two and a regular rotation of dosing be practised1 each bed would rest not only the time between the regular twelve-hour period dosing1 but might also be given a complete rest1 occasionally1 for an extended period4 ,this third requirement is probably less imperative with the coarser particles and there are many examples of coarse-grained beds which have been continuously operated for a period of years4 ,it is found1 however1 that with such treatment clogging is inevitable1 and that such clogging is partially relieved by a period of rest somewhat proportional to the length of time the beds have been operated4 ,it is1 then1 only shortsighted policy to economize at the beginning and attempt to save money by not building an additional area1 since the clogging of the whole plant is bound to occur in the course of time1 and then another plant must be built or the material forming the bed taken out1 washed1 and replaced4 ,otherwise the sewage must go unpurified to the outfall while the bed is recovering from the long period of overwork4 ,it is convenient to divide sewage purification into two processes1 the preliminary process and the final1 or finishing process1 and1 while the preliminary process1 in itself1 never accomplishes purification1 yet it is of considerable value in facilitating and increasing the rate and efficiency of that purification4 ,the most common preliminary treatment is sedimentation1 by which the larger solids in suspension are allowed to settle in a tank or tanks so that the filter beds later used are relieved from the accumulation of those deposits4 ,under the name of septic tank such a receptacle for suspended solids has been exploited as a complete method of purification1 and many underground tanks have been constructed in various parts of the country which have1 at the time of their installation1 been considered competent to furnish all the necessary purification4 ,when it is remembered that less than one-half of the organic matter in sewage is in suspension and that the best results in any sort of a tank succeed in depositing only one-half of those suspended solids1 it can readily be seen that a tank1 whether called septic or settling1 cannot be a complete method of treatment4 ,in reality1 such a tank does little more than take out from the sewage the greasy material and a certain proportion of the suspended matter4 ,whatever part of this is organic matter may1 by a particular arrangement of the tank1 be considerably reduced in quantity1 so that the intervals of cleaning can be extended1 but in every tank the removal of the deposits is necessary1 and subsequent treatment is required if adequate purification is accomplished4 ,the final1 or finishing1 process may be carried out according to any one of several methods4 ,it may be done by discharging the tank effluent into a system of agricultural drains laid just below the surface of the ground1 called sub-surface irrigation4 ,it may be done by removing the top soil from a bed of sand placed by nature1 and needing little except suitable surface distribution to insure the most efficient purification4 ,for a small plant1 instead of a sand filter1 for which the sand is found naturally in a suitable location1 an artificial filter may be built by preparing an enclosure and carting in sand for filling4 ,where no sand is available1 or where its use would be uneconomical1 broken stone may be used to ensure final treatment4 ,with stone1 on account of its large voids1 the enclosure must either be water-tight1 and the outlet pipe must be provided with a valve or other device so that the sewage under treatment may be held in the enclosure or tank long enough to deposit the solids in suspension and to be acted on by the bacteria concerned4 ,this method is known as the contact bed treatment4 ,or1 finally1 the desired results may be obtained by spraying the sewage onto a deep layer of broken stone1 the method being called the sprinkling filter treatment4 ,the choice of the final treatment1 in any particular case1 depends on the character and slope of the ground1 on the availability and cost of sand or of broken stone1 and on the amount of sewage to be treated4 ,it is hoped that the following pages will give to the reader both an intelligent appreciation of the advantages and disadvantages of each of the several methods of sewage purification discussed1 and also sufficient insight into the necessary details of construction so that the method chosen can be put into successful operation4 ,,chapter ,,ii ,,the ,,settling ,,tank ,,and ,,its ,,construction ,as has been stated1 a most effective preliminary step in the treatment of sewage is to pass it through a properly designed settling tank in order that the grosser solids and suspended matters as far as possible may be deposited there and finally disposed of separately from the liquid sewage4 ,this partial removal of the suspended matters1 amounting to about fifty per cent4 in well-designed and carefully operated tanks1 very materially aids in the final treatment of sewage on filters or on sub-surface irrigation areas by preventing clogging of the filters or of the piping in the irrigation system4 ,in connection with the larger settling tanks for hotels or institutions1 it is sometimes advisable to pass the sewage first through a screen chamber before it is discharged into the settling tank1 in order that the grosser suspended solids may be collected more easily than from the tank2 but1 as has been pointed out1 screening of sewage is not necessary at small disposal plants1 and in fact is not generally advisable owing to the continual labor involved in removing and disposing of the screenings1 and no description of screening plants will therefore be given4 ,the old method of discharging sewage and house wastes into loose-walled cesspools on all occasions and under all sorts of conditions is rapidly changing1 as is desirable4 ,true1 in certain locations1 where ample area is available1 where the soil is dry and porous1 and where neither springs nor wells nor the soil near dwellings will be contaminated thereby1 cesspools may be safely used4 ,in other locations a small expenditure of time and money will provide the means by which nature's processes of reduction of the organic matter in sewage may be carried on much more efficiently and satisfactorily than ever can be the case in a cesspool4 ,illustration3 ,,fig4 #a4--,plan of ,settling ,tank4 ,the scheme for properly disposing of sewage at any point should therefore include its sedimentation in a settling tank of proper construction and ample capacity1 whether its final treatment is to be effected by sub-surface irrigation1 intermittent sand filtration1 contact beds1 or sprinkling filters4 ,where the sewage effluent is to be discharged into a stream or body of water of comparatively large flow or volume1 and where that stream is not subsequently used as a potable water supply1 it is sometimes permissible to subject the sewage to settling tank treatment only4 ,such partial treatment1 however1 should be arranged for only as a temporary measure1 and the tank should be so constructed with respect to the elevation of adjacent areas that works for final treatment of sewage1 when required1 may be constructed as advantageously as possible4 ,moreover1 in the more progressive ,states1 as noted in ,chapter ,i1 the purity of streams is being carefully safeguarded1 and the general tendency of public health officials is to require more complete treatment of sewage before its discharge into a watercourse than is accomplished by settling tanks4 ,the settling tank for residences and institutions1 as shown in ,fig4 #a1 should have a capacity of from five to fifteen cubic feet for each person served by the sewer in order that proper time of detention in the tank may be allowed for the sedimentation of the suspended matters in the sewage4 ,the depth of the tank should be from five to eight feet1 and its width should generally be from one-third to one-half the length4 ,fig4 #b shows a longitudinal section of the settling tank and siphon chamber4 ,illustration3 ,,fig4 #b4--,longitudinal ,section of ,settling ,tank4 ,the following table gives the dimensions of tanks which should be adopted to provide a proper time of detention of sewage1 based on the number of persons to be served3 ,,table ,i ,,dimensions ,,for ,,settling ,,tanks ,persons ,served by ,sewer4 ,mean ,mean ,depth ,inside ,inside 7,feet74#a ,width ,length 7,feet74 7,feet74 #d #c #d #e #h #c #g #e #ab #d #g4e #e #ae #d #h #e #be #d #aj #e #ce #d4e #ab #e #ej #f #ab #e #ge #f #ae #f #ajj #g #ag #f #abe #h #ag4e #f #aej #h #ah #f #age #h #bj #f #bjj #h #bb #f #bej --#b compartments in tank1 each #e4e #ah #f #cjj --#b compartments in tank1 each #e4e #ah4e #g #cej --#b compartments in tank1 each #f #ai #g #djj --#b compartments in tank1 each #f #ai #h #dej --#b compartments in tank1 each #f #bb #h #ejj --#b compartments in tank1 each #f #bd #h ,footnote #a3 #ab inches greater than depth of sewage4 ,illustration3 ,,fig4 #c4--,sketch of ,settling ,tank with ,longitudinal ,partition ,wall4 ,the dimensions of settling tanks given above provide for longer periods of detention in the case of the smaller tanks than in that of the larger1 an excess which is necessary on account of the greater fluctuation in the flow of sewage reaching the smaller tanks4 ,the larger tanks may be better and more conveniently operated if they are divided by a longitudinal partition wall as shown by ,fig4 #c1 and arranged for in the table for tanks serving #bej or more persons4 ,this provision is not so necessary in the case of the smaller tanks1 especially if they are to be installed at summer resorts or country homes occupied for only a few months in the summer4 ,if1 however1 the tanks are to be operated continuously they may have two chambers for greater convenience in removing sludge4 ,the flow through one compartment may then be stopped by closing a valve placed on the inlet pipe to that compartment1 or by inserting one of the stop-planks or sluices in a diverting chamber1 as shown in ,fig4 #c1 at the left of the tank and inserting a ten-inch board in the groove over the outlet weir wall of the compartment to be cleaned4 ,the entire flow of sewage is then passed through the other compartment while the first is being cleaned4 ,this division of the tank into two compartments is sometimes desirable in the case of the smaller tanks and may easily be accomplished4 ,for instance1 instead of a tank #f feet by #ab feet1 two compartments may be arranged for1 each #c feet #f inches by #aj feet2 and instead of a tank #h feet by #bj feet1 two compartments may be constructed1 each #e feet wide and #af feet long4 ,the settling tank should be located as far as conveniently possible from the dwelling1 and especially from any wells or springs1 in order that leakage of sewage1 which may always occur1 will not lead to the contamination of a water supply or of the soil near the residence4 ,it may not be possible in every case to locate such tanks more than fifty feet away from the house or from the well1 but the distance should never be less than this1 and when located at this minimum distance from the dwelling or from a well1 especial care should be used to make the tank water-tight4 ,the walls of the tank should preferably be constructed of concrete1 although they may be built of brick or wood4 ,the last material is often the cheapest1 and tanks constructed of lumber will last for several years without renewal4 ,the concrete tank1 however1 is more easily made water-tight1 and is a permanent structure4 ,the walls of the tank1 when the height is less than #h or #aj feet1 should be #h inches thick at the top1 and should have a batter on the inside of #a inches per foot of height4 ,if the tank is to be built with two compartments1 the partition wall should be #aj or #ab inches thick at the top and should have a batter on both sides4 ,the tank should generally be placed with its top at the level of the ground surface1 and the sewer from the house should enter the end of the tank with its flow line or invert #ab inches below the top of the walls4 ,the house sewer or drain should have a grade or fall of not less than #i inches in #ajj feet4 ,preferably1 the sewer should be laid at the above minimum grade for at least #ej feet or so before it enters the tank in order to prevent excessive velocity in the sewage flow at this point4 ,at the entrance to the tank the sewer should be provided with an elbow so that the sewage will be discharged downward below the surface4 ,similarly1 if an outlet pipe from the tank is used1 as shown in ,fig4 #e1 this pipe should pass through the wall at the outlet end of the tank1 one foot below the top of the tank1 and should also be provided with an elbow which will start from below the surface4 ,where a siphon is to be used to discharge the effluent from the tank onto a filter or into a system of sub-surface tiling1 the separate chamber in which the siphon must be placed may be built as an extension of the settling tank so that the end wall of the settling tank will serve as one of the walls of the siphon chamber4 ,the siphon chamber floor may be placed considerably above the level of the floor of the tank as shown in ,figs4 #b and #c1 since a sufficiently large quantity of effluent for dosing a filter or a sub-surface irrigation system may be collected in the chamber of reduced depth thus provided4 ,this shallower construction saves excavation and also reduces the operating head or fall1 which latter is sometimes hardly equal to the demands of the subsequent treatment4 ,the capacity needed in this chamber for different installations will be given later in the discussion of sewage filters and sub-surface irrigation systems4 ,having determined upon the dimensions of the tank and selected the site1 the construction is commenced by making the excavation about four feet wider and longer than the outside dimensions of the tank and siphon chamber combined1 in order to provide room for setting the forms for placing the concrete1 provided concrete is to be used in its construction4 ,with brick walls an additional width and length of two feet is needed4 ,fig4 #d gives an illustration of the forms to be used in constructing the walls for concrete tanks1 the cut at the left showing a view of the form to be used when the tank is constructed either partly or wholly above the natural ground surface1 or below the surface in loose soils1 and the cut at the right showing a view of the form to be used when excavation for the tank is made in rock1 hardpan1 or clay4 ,the top width of the walls should be #h inches1 and the bottom width should be #h inches plus #a inches for each foot of height4 ,thus1 for a wall #f feet high the bottom width should be #ag inches1--the inside face of the wall having a batter of #a inches per foot of height4 ,this batter is necessary1 when the tank is constructed below the ground surface1 to withstand the lateral earth pressure when the tank is empty4 ,if the tank is to be constructed above the ground surface1 the outside wall should be battered and the inside wall made vertical1 since the pressure which the wall must withstand is then only from the liquid within the tank4 ,the partition wall between the settling tank and siphon chamber should be #aj or #ab inches thick at the top1 depending on its height1 and should have a batter on both sides4 ,illustration3 ,,fig4 #d4--;,forms ,used for ,building ,side ,walls for ,concrete ,tank4 ,to set up the forms for the concrete walls1 stakes #b inches by #d inches and about #b feet long are first driven on each side of the bottom of the wall1 and #f inches away from the wall as laid out1 at intervals of #b feet4 ,pieces of scantling1 #b inches by #d inches and with a length equal to the height of the wall1 are then placed in upright position and securely nailed to these stakes4 ,the inner scantling are then inclined and temporarily fastened at the top by a short nailing piece to the outer row so as to leave an opening of #aj inches between each pair of scantling4 ,additional stakes are then driven from #b to #d feet from the wall on each side1 as shown in the illustration1 and braces #b inches thick and #c inches or #d inches wide are nailed to these stakes and to the upright and inclined scantling4 ,one-inch boards are then lightly nailed to the scantling1 as shown1 the boards making up the inside face of the form being placed in sections of two feet in order to afford opportunity for thorough tamping of the concrete as the form is being filled4 ,the concrete is then placed between the boarded sides of the form in #f-;inch layers and well rammed4 ,the concrete should be composed of one part by measure of ,portland cement to two and a half parts of clean1 sharp building sand and five parts of broken stone or clean gravel4 ,the cement and sand should first be thoroughly mixed1 while dry1 to an even color and then wet and tempered to a soft mortar4 ,the broken stone or gravel1 after having first been thoroughly wet1 should be spread evenly over the batch of mortar and the mass shoveled over at least three times to insure a thorough coating of the stones with mortar4 ,the concrete thus made may then be placed in the forms in six-inch depths and thoroughly rammed until water covers the surface4 ,when it is essential that the tank be water-tight1 and1 in fact1 in constructing all tanks1 each layer of concrete should be placed between the forms1 when possible1 before the concrete in the layer previously placed has set4 ,if the work of placing the concrete is of necessity interrupted1 before placing another layer the surface of the older concrete should first be sprinkled and swept with a stiff broom and a thin coating of neat cement mortar 7containing no sand7 should then be washed over the surface of the concrete4 ,it may be noted that a barrel of ,portland cement 7equal to four bags7 contains #c4h cubic feet1 so for concrete with the proportions of cement1 sand1 and stone as specified above1 for each barrel of cement used there should be used #i4e cubic feet of loose sand and #ai cubic feet of loose stone2 and for each cubic yard of concrete required there will be needed #a4cj barrels 7or #e4b bags7 of cement1 #j4df cubic yards of sand1 and #j4ib cubic yards of stone if the stone is fairly uniform in size and contains forty-five per cent4 of voids4 ,with stone or gravel less uniform in size1 less cement and sand is required4 ,the cement and sand1 made into mortar1 will fill the voids or open spaces in the mass of broken stone4 7,for further details see ,chapter ,,vii47 ,as shown in the illustration 7,fig4 #d71 the foot of each upright and inclined scantling should be placed at the proposed elevation of the floor of the tank1 and the boarding should not be carried below this level4 ,then1 if the excavation for the wall has been carried to a level #f or #h inches lower than the floor of the tank1 the concrete when being placed between the forms will spread under the bottom of the forms1 making a footing for the wall on the outside and better insuring a water-tight joint when the floor is laid against the inside foot of the walls4 ,in making the excavation for the tank1 after reaching the proposed level for the floor a trench should be cut around the floor space to a depth of #f to #h inches below the floor level4 ,the width of this trench should be such as to extend from #f to #h inches inside and an equal distance outside the wall at the floor level4 ,after the walls have been constructed as described1 the forms should be left in place for at least #bd hours1 to allow the concrete to set1 and then removed4 ,the excavation inside the walls should then be carried #f inches below the floor level1 the soil well tamped1 and a #f-;inch layer of concrete placed to form the floor of the tank4 ,it is well to sprinkle all concrete daily until it has thoroughly set4 ,if the type of siphon selected has a ,u-shaped pipe extending below the floor of the siphon chamber1 it will be necessary to set the siphon in position while the floor is being laid and the discharge pipe in position while the wall is being laid4 ,the siphon should be so placed that the bottom of the bell over the longer leg is #c inches above the floor of the siphon chamber or of the sump in the siphon chamber if such a depression is made in the construction of the floor4 ,illustration3 ,,fig4 #e4--,view of ,settling ,tank1 ,showing ,baffles1 ,sludge ,pipe1 ,drain ,pipe1 and ,inlet and ,outlet ,pipes4 ,the floor of the tank should slope toward the inlet end at a rate of one-half inch per foot of length in order to facilitate the removal of sludge when the tank is being cleaned4 ,this will result in providing a somewhat greater depth at the inlet end of the tank than is shown by the tables1 and a lesser depth at the outlet end1 leaving the depth at the centre of the tank as shown4 ,the inlet and outlet pipes to the tank1 which should be of cast iron1 should be placed in position through the forms while the walls are being laid4 ,when it is desired to have an outlet pipe from the tank near the bottom 7see pipe ,a1 ,fig4 #e71 for the purpose of drawing off the supernatant liquid1 and so saving the labor of removing the liquid by pail when the tank is being cleaned1 this pipe should be of cast iron1 #d inches in diameter and fitted with a valve and valve rod placed outside the tank1 and should also be placed in position during the construction of the tank4 ,the valve rod1 or stem1 should reach to the surface of the ground through a #c-;inch pipe casing4 ,the lower outlet pipe should be extended around the siphon chamber to discharge into the effluent pipe leading away from this chamber1 when possible4 ,this lower outlet pipe should leave the tank at least one foot above the floor and sometimes at a higher elevation1 in order to discharge into the sewer leading to the irrigation field or to the filter4 ,pipe ,b in ,fig4 #e shows a sludge pipe which may be laid to a suitable site for disposing of sludge from the tank when the slope of the land will permit the draining of the sludge by gravity into trenches or onto a sludge bed4 ,this sludge pipe should be fitted with a valve and valve stem1 and the valve may be inside the tank1 as shown in the illustration1 or outside the tank1 as shown on pipe ,a4 ,if such an arrangement for disposing of sludge is possible1 it is manifestly unnecessary to provide pipe ,a as shown in ,fig4 #e1 since the supernatant liquid as well as the sludge may then be piped to a sludge bed or pit4 ,this bed should be shallow1 but of ample capacity to hold the entire contents of the settling tank4 ,the sludge may then be drawn off about every six weeks1 thereby operating the tank as a settling tank rather than as a septic tank4 ,it will be found after scum of a certain thickness has formed on the surface of the sewage in the tank that the thickness will not materially increase4 ,the roof of the tank should preferably be of concrete renforced with iron rods1 although it may be of brick arches or of two-inch planking4 ,the use of brick for the roof is not advisable1 however1 since the forms for the construction of the arches are rather difficult to make1 and brick roofs are apt to be broken down sooner or later through the action of frost4 ,a wooden roof1 also1 must be renewed at intervals and is not as satisfactory as a concrete roof4 ,illustration3 ,,fig4 #f4--,section ,showing ,tank with ,concrete ,roof and with ,form for ,constructing ,roof4 ,a section of a tank with a concrete roof is shown by ,fig4 #f1 together with the temporary form built up inside the tank on which to lay the roof4 ,the form is built by setting #b-;inch by #d-;inch scantling on wedges along the walls of the tank in pairs #ah inches apart and bracing these at the foot4 ,boards #a inches thick and #aj inches wide are then nailed across the tank to the tops of the scantling1 the top edges of the boards being #a inch below the top of the walls4 ,a false roof is then made of boards nailed lengthwise of the tank to the #aj-;inch boards1 and a layer of concrete #b inches thick is then placed on the floor thus made1 reaching over the top of the walls to the outside edges4 ,iron rods1 of an inch thick and spaced #a foot apart1 are then placed on the concrete across the tank and reaching to within #a inch of the outside edges of the walls4 ,more concrete is then placed over the first layer to a total depth of #f inches or #h inches1 depending on the width of the tank1 the concrete being well rammed as it is placed4 ,after the concrete has set1 the wedges may be knocked from under the upright scantling and the form taken down and removed through the manhole4 ,the manhole covers and frames1 as shown in the illustrations in ,chapter ,,iii1 may be cast at local foundries or purchased through sewer-pipe dealers4 ,to provide manholes or openings through the roof into the tank and into the siphon chamber1 round openings #b feet in diameter should be cut in the false roof while it is being laid1 the distance between the pairs of scantling at this point being made #b feet4 ,the manhole frames should then be so placed that the flange or base of the frame will be imbedded to a depth of #b inches in the roof when completed4 ,the manhole at the entrance end of the tank should be located at one side of the entrance pipe and over the valve on the sludge pipe4 ,to provide the necessary opening through the concrete roof below the manhole frame1 an eight-sided wooden form1 as shown in ,fig4 #g1 with an inner diameter of #b feet and a height equal to #b inches less than the thickness of the roof1 is placed over the opening in the false roof4 ,on this wooden form the manhole frame is placed and the concrete laid around the form and over the flanges of the manhole frame4 ,two of the -inch iron rods should be placed across the tank close to each side of the wooden form after the first #b-;inch layer of the concrete roof has been placed4 ,illustration3 ,,fig4 #g4--;,form for ,manhole ,opening4 ,when it is desired to carry the manhole some distance above the level of the top of the roof to provide for a rather deep earth covering for the tank1 the eight-sided wooden form may be made deeper as desired1 and another larger1 similar form built for the outside form of the necessary concrete manhole well4 ,the space between the two forms may then be filled with concrete and the manhole frame set on the octagonal-shaped wall thus formed4 ,in order to insure a more uniform flow of sewage through the tank and thus reduce the velocity of flow in all portions to a minimum1 baffle boards of #b-;inch planks should be placed across the tank near the inlet pipe and near the outlet pipe1 as shown in ,fig4 #e4 ,these boards are set in grooves formed in the concrete by nailing #a-;inch by #c-;inch strips to the inside form when the tank wall is constructed4 ,these baffles also serve a useful purpose by reducing the disturbance of the scum as the sewage enters the tank and by preventing the escape of scum from the tank4 ,the boards should extend to a depth of one foot below the inlet and outlet pipes1 and should usually be placed #ab to #ah inches from the ends of the tank4 ,where the effluent from the tank is to be collected in a siphon chamber adjoining the tank1 it is preferable to provide a weir or wall between the tank and the siphon chamber4 ,the top of this wall should be one foot below the roof to allow the effluent to flow over this wall from the tank into the siphon chamber4 ,in this case no outlet pipe from the tank is used1 and the baffle boards should extend downward #ab inches below the level of the sewage in the tank4 ,these baffle boards should be carried up to a level with the top of the tank walls4 ,it is advisable to provide an overflow pipe from the siphon chamber which should leave this chamber at an elevation of #c or #d inches above that of the inlet pipe to the tank1 and which should1 by means of an elbow1 be extended down outside the chamber to connect with the sewer into which the siphon discharges4 ,this is desirable in order to provide an overflow in case the siphon becomes clogged or fails to operate4 ,where a tank must of necessity be located near a residence1 any nuisance due to odors may be prevented by inserting a #d-;inch galvanized-iron conductor-pipe through the roof of the tank1 and carrying this pipe up into the air #bj or #cj feet along a tree trunk or the side of a building4 ,if a sub-surface irrigation field is to be laid out1 the tank should preferably be near the proposed location of the sub-surface irrigation area 7see ,fig4 #bf1 ,chapter ,,iv71 although the effluent may be carried to the sub-surface irrigation field from a settling tank located at some distance from such field4 ,since the sewage enters the tank near the top of the tank and the effluent discharges from the siphon chamber at a considerable distance below the top of the tank1 it is of advantage to place the settling tank on sloping ground1 if possible1 so that one end will be wholly in excavation and the other will be partly above the natural ground surface4 ,this reduces the depth of trenching and provides for more readily distributing the effluent by gravity from the tank through the sub-surface tiling which is laid just below the surface of the ground4 ,the tank must always be higher than the distributing field to allow for the flow of sewage1 and it is desirable to have the tank buried in the ground if possible in order to keep the temperature of the sewage as high as possible in winter4 ,these ideal conditions are not always to be attained4 ,the one important point to be kept in mind if the settling tank is to be properly operated and not allowed to develop into a nuisance is that the sludge or sediment must be removed from the bottom of the tank at intervals before the effective capacity of the tank is so reduced that the proper sedimentation of the sewage is impossible4 ,the frequency of cleaning necessary varies in different cases1 but usually the tank should be emptied and cleaned at intervals of from three months to one year1 and where the contour of the ground allows the sludge to be readily drawn off into trenches or to a sludge bed1 cleaning should be practised every five or six weeks4 ,there is1 perhaps1 little need for cleaning the tank as often as once in six weeks1 but it is generally found and has been affirmed in court testimony that the removing of the sludge from a settling tank once every six weeks will prevent septic action from taking place1 and the tank will then be operated as a settling tank and not as a septic tank4 ,this is desirable in view of the fact that royalties have been claimed under certain patents on septic tanks4 ,as explained on p4 #aa1 the important function of the tank is to settle out suspended solids1 while the processes that take place in the septic tank but not in the settling tank are of minor importance1 and it is advisable therefore to operate these tanks as settling tanks when possible4 ,in no case should the sludge be allowed to accumulate until it fills more than one-quarter of the tank4 ,the sludge may be disposed of by burying in trenches or ploughing under1 or it may be spread on the surface at points remote from highways and dwellings or sources of water supply4 ,the depth of accumulated matter in the tank should frequently be tested at the inlet end by using a pole or stick4 ,illustration3 ,,fig4 #h4--,plan and ,longitudinal ,section of ,modified ,imhoff ,tank4 ,illustration3 ,,fig4 #i4--,vertical ,cross-,section of ,modified ,imhoff ,tank4 ,in reference to the preliminary treatment of sewage in tanks1 it should be noted that the most recent development in the design of sewage-disposal plants has been the improved method of sedimentation of sewage represented by the ,imhoff or ,emscher tank4 ,a modified design of this tank is shown in plan and longitudinal section in ,fig4 #h1 and a cross-section of the tank is shown in ,fig4 #i4 ,the principle employed is to provide a separate chamber for storing the sludge which results from the sedimentation of the suspended matters in the sewage1 this chamber being almost entirely separated from the portion of the tank in which the sedimentation takes place4 ,this separation of the sludge from the flowing sewage is accomplished in the tank shown by inserting in the tank1 parallel with the side walls1 two inner partitions ,,aa1 which are vertical for a few feet below the surface of the sewage and then slope toward the centre line of the tank1 but1 as shown by ,fig4 #i1 do not meet at the centre line1 the one passing a few inches under the other4 ,the opening or slot thus formed between the two inner partitions allows the suspended matters which settle out of the sewage flowing through the upper compartment to pass into the lower or sludge compartment and there remain in a quiescent state until removed from the tank4 ,the object of this separation of the sludge from the flowing sewage is to prevent the gas bubbles which emanate from the sludge during its decomposition from rising through the flowing sewage and interfering with the process of sedimentation going on in the upper compartment1 and to provide for a more complete decomposition or 8digestion0 of the sludge4 ,the gas bubbles on rising from the deposited sludge strike the sloping lower sections of the inner partitions and are deflected to the portions of the tank next to the outside walls4 ,a sludge pipe leads away from the bottom of the hopper-shaped sludge compartment1 and at intervals of from one to four weeks the valve on this sludge pipe is opened for a short time and a small portion of the accumulated sludge is allowed to be forced out onto a sludge-drying bed by the weight of the sewage in the tank4 ,the portion of the sludge thus removed has1 of course1 remained in the tank the longest time1 generally five or six months1 and has had the fullest opportunity to be reduced and rendered inodorous and easy to dispose of4 ,this method of sedimentation was first experimented with about twelve years ago by ,mr4 ,h4 ,w4 ,clark at the ,lawrence ,experiment ,station of the ,massachusetts ,state ,board of ,health1 then partially developed by ,dr4 ,w4 ,owen ,travis1 of ,hampton1 ,england1 and finally worked out by ,dr4 ,ing4 ,carl ,imhoff in connection with the disposal of sewage in the ,emscher ,river district in ,germany4 ,the method has been extensively and successfully used in ,germany1 and similar tanks are now being installed in this country4 ,while these tanks are probably more effective than septic tanks and the usual type of settling tanks in the removal of suspended matters in sewage1 their chief value will undoubtedly be found in the rendering of the sludge less odorous and more easily handled4 ,this form of settling tank is covered by patents1 and a moderate royalty is charged on tanks of this type4 ,a description of the ,imhoff tank has been here included since it represents an important development in sewage disposal and helps to solve what has heretofore been one of the main difficulties of sewage disposal1 especially for cities and villages1 namely1 the satisfactory and convenient disposition of sludge2 but it is not considered that their construction is advisable or warranted where only a small quantity of sewage is to be treated1 and settling tanks to treat sewage contributed by less than1 say1 two hundred persons would generally be constructed as previously described4 ,,chapter ,,iii ,,valves1 ,,siphons1 ,,and ,,siphon ,,chambers ,it was explained in ,chapter ,i that one of the essentials of successful sewage purification is an intermittent application of the sewage to the beds in which bacteria are to act4 ,this intermittent action is secured by providing a small additional tank or by setting aside a part of the settling tank and by installing therein some kind of mechanism for the purpose of changing the more or less regular flow into an intermittent or periodical flow4 ,the proper capacity of this tank will be considered later in the chapters dealing with the several methods of final purification4 ,now it may be said only that the size depends on the amount of sewage to be cared for per day and on the size of the dose demanded by the purification method4 ,the size of dose depends directly upon the method of treatment and on the size of the particles in the beds intended to receive the sewage4 ,on sand beds1 for example1 it is customary to discharge the sewage from the dosing tank three times a day1 although many plants operate with a daily discharge4 ,the size of the dosing tank1 however1 in the latter case has to be three times as large as in the former1 and it is usually worth while to take the additional trouble of having more frequent operation in order to save the cost of the larger tank4 ,the simplest method of construction of the dosing tank is to make it a part of the sedimentation tank by means of a cross wall1 which latter must be strong enough to withstand the pressure of the water on one side when the dosing tank is empty4 7,see ,figs4 #b and #c47 ,there is no objection to this tank being separate and some distance away from the sedimentation tank1 and sometimes1 for convenience in distributing the sewage from the dosing tank onto several beds in turn1 the dosing tank is placed at the centre of a group of beds with the settling tank outside4 ,if the dosing tank is a part of the main tank1 the sewage flows into it over a dividing wall between the two tanks or through a pipe laid through this wall1 while if the tank is separate from the other1 then a longer pipe connection is required4 ,illustration3 ,,fig4 #aj4--,sludge ,valve for ,floor of ,tank4 ,it is economical to arrange that the level of the sewage in the dosing tank1 at the time when that tank discharges1 shall be at the level of the sewage in the settling tank1 since then no head is lost4 ,it is better still to arrange the mechanism in the dosing tank so that the level of the sewage there at the time of its discharge will be from four to eight inches higher than the normal level in the settling tank4 ,the effect of this is to back up the sewage and raise the general level in the settling tank1 and when the dosing tank discharges there is drawn off not only the sewage in that tank1 but also an amount in the large settling tank equivalent to that which is above the normal level of the sewage there4 ,the advantage of this is plain in that it reduces the necessary volume of the dosing tank by that of the back water in the settling tank1 and1 while it was thought at one time that such a frequent variation in the level of the main tank might affect injuriously the scum which forms there1 and perhaps also the bacterial action going on in the tank1 there seems to be no real reason why this method may not be used with considerable advantage in economy of construction4 ,the bottom of the dosing tank1 which is preferably made of concrete1 should have a slope toward the point from which the outlet pipe leads1 thus enabling the outward rush of sewage to carry off any material which would otherwise settle in the bottom and perhaps decompose there4 ,illustration3 ,,fig4 #aa4--,sludge ,valve for ,side ,wall of ,tank4 ,the simplest method of operating the dosing tank is by means of a hand valve fastened either to the floor of the chamber or to the bottom of the outside wall4 ,fig4 #aj shows a simple form of a valve suitable for the floor and intended to be operated by a rod extending up through the sewage to the outside air4 ,such a valve can be made at any local foundry1 the bearing surfaces turned up in any machine shop1 and a piece of leather for packing purchased at any hardware store4 ,such a design1 however1 is not suitable for a large valve or for a great depth of water1 since the pressure on the valve is dependent on the weight of the column of water acting on its area4 ,if the outlet pipe is six inches in diameter1 the diameter of the upper surface of this valve would be about ten inches1 and the area of the top of the valve would be about half a square foot1 so that1 with six feet of water above1 weighing #fb pounds per square foot1 the weight on the valve to be lifted would be #ahf pounds1 rather more than could be lifted by one man4 ,under such conditions it would be necessary1 using such a valve1 to rig a lever1 the fulcrum being fastened to the edge of the tank1 the short end of the lever to the rod1 and the long end so arranged as to reduce the load in the ratio of about one to four4 ,fig4 #aa shows another type of valve intended to be set into the side of the tank with the floor sloping rapidly toward the low point at which this valve is set4 ,these valves require better workmanship and are preferably purchased from one of the dealers in valves who make this type as one of their regular stock forms4 ,fig4 #ab shows the design made by the ,coffin ,valve ,company1 of ,troy1 ,n4 ,y41 and a similar form of valve is made by the ,caldwell-,wilcox ,company1 ,newburg1 ,n4 ,y4 ,for a six-inch pipe1 these valves are so made that the danger of the moving parts rusting together is avoided by having one surface bronze or some similar noncorrosive metal4 ,fig4 #ac shows an ordinary gate valve generally used for water works1 but applicable to sewerage works4 ,such a valve is shown in ,fig4 #e4 ,illustration3 ,,fig4 #ab4--,sluice-,gate ,valve made by ,coffin ,valve ,co4 ,illustration3 ,,fig4 #ac4--,ordinary ,gate ,valve4 ,fig4 #ad shows a form made in ,england and largely used as a cheap valve for the purpose of emptying a tank rapidly4 ,the peculiarity of the valve is that a sidewise motion of the long handle locks the valve into position so that the moving part of the valve may be readily set at any height4 ,the one shown in the figure is taken from the catalogue of the ,adams ,hydraulic ,company1 ,westminster1 ,london1 and is listed in their catalogue at #f4ej for a six-inch pipe4 ,illustration3 ,,fig4 #ad4--;,english ,slide ,valve with ,wedge-lock ,handle4 ,fig4 #ae shows another type of valve which is supplied by some firms making sewer pipe and consists1 as may be seen1 of a light moving valve which is attached to a projection cast on the top of the vitrified tile pipe in such a way that the valve comes to an even seat on the bevelled end of the pipe4 ,it is found that with pressure acting against the valve the thin metal of which it is composed is pressed against the pipe so that little1 if any1 water or sewage will escape4 ,the valve can easily be opened by attaching a cord or chain to the ring at the lower edge of the valve1 and when released the valve shuts automatically4 ,this is a very cheap and convenient design1 and answers every purpose for emptying tanks by hand4 ,more elaborate structures of the same general type have been made1 using cast iron as the metal1 the stationary collar with the bevelled end being built into the masonry wall of the tank4 ,this type of flap valve is faced with bronze1 and the bearings or joints have bronze bushings4 ,a satisfactory valve of this sort can be made at a local foundry and machine shop1 but there is danger that the valve will not be water-tight4 ,fig4 #af shows such a valve with the metal seat which is intended to be bolted into the masonry of the tank wall4 ,illustration3 ,,fig4 #ae4--;,flap ,valve ,attached to ,length of ,sewer ,pipe4 ,fig4 #ag shows another form of this same sort of valve1 taken from the catalogue of the ,adams ,hydraulic ,company1 and noteworthy because of the loose-link connection at the upper part of the valve1 the object of this being to prevent the valve closing at the upper part without1 at the same time1 closing at the bottom4 ,if the dosing tank is to work automatically and independently of human agency1 an arrangement which is always preferable1 there must be installed some mechanism which takes the place of the valve operated by hand4 ,this mechanism is in almost every case a siphon which is put into action when the water level reaches a certain height1 and which discharges rapidly until the water falls to a point when air is admitted to the inside of the siphon pipe1 thereby interrupting the flow4 ,illustration3 ,,fig4 #af4--;,flap ,valve with ,metallic ,seat ,attached4 ,there is on the market a dosing apparatus which does not involve a siphon1 and which is shown in ,fig4 #ah4 ,this is made by the ,ansonia ,manufacturing ,company1 #cj ,church ,street1 ,new ,york ,city1 and its operation may be described as follows3 ,it consists of two floats connected by means of a chain which passes over a wheel supported in the upper part of the chamber4 ,as the water in the chamber rises1 the left-hand float shown in the drawing rises and the right-hand float falls1 thereby communicating a rotary motion to the wheel4 ,a projection on this wheel at a certain point when the left-hand valve has reached the desired height communicates with an inside portion of the wheel1 to which a chain connected with the valve is attached4 ,thus the valve is opened at the right height1 and remains open until the water has fallen to the bottom of the chamber4 ,then the left-hand float falls1 and the apparatus is ready to repeat the operation4 ,this apparatus1 for a small installation1 will probably cost1 set up in place1 about #ae4 ,illustration3 ,,fig4 #ag4--;,flap ,valve with ,loose-link ,hinges4 ,fig4 #ai shows the simplest form of siphon arranged to discharge water from a tank4 ,it will be noticed that it consists of an inverted bent pipe1 one leg being longer than the other1 and extending into a pool of water formed in the end of the discharge pipe4 ,when the water level in the tank reaches the bent portion of the siphon pipe1 the water begins to flow out1 and will continue to flow until air is drawn in at the lower end of the short leg4 ,this stops the flow and the tank begins to fill again4 ,fig4 #bj shows another method of working the siphon and insuring its rapid initial action4 ,this is known as the ,van ,vranken flush tank1 and the feature of this arrangement is the movable bucket1 which in one position seals the lower end of the longer leg4 ,then1 however1 the siphon begins to act1 and the bucket1 which is hung on trunnions1 is disturbed and its contained water is dumped out4 ,this allows the escape of the water in the longer leg and insures a vigorous starting up of the siphon into action4 ,illustration3 ,,fig4 #ah4--;,intermittent ,dosing ,apparatus made by ,ansonia ,m'f'g ,co4 ,a more simple type1 however1 is the inverted siphon arrangement1 developed perhaps most completely by the ,pacific ,flush ,tank ,company under the ,miller patents4 ,fig4 #ba shows their ordinary design1 the upper part of the siphon being replaced by a bell and the discharge starting when the level of the water in the long leg of the siphon has been depressed sufficiently to reach the curved part of the pipe4 ,the principle on which this siphon works is as follows3 ,illustration3 ,,fig4 #ai4--,simplest form of ,automatic ,siphon4 ,when the water rises in the tank above the lower edge of the bell1 the air which remained between the water in the siphon pipe and in the bottom of the tank is confined1 and1 as the water rises1 is gradually compressed4 ,the effect of this compression is to force down the water in the long leg of the siphon and to hold down the level of the water inside the bell lower than the level outside4 ,when sufficient head of water in the tank is secured1 the water inside the pipe will be forced down to the curved part of the pipe1 and1 the siphon being so designed1 the water level inside the bell will be just at the top of the same pipe1 but on the outside4 ,any slight additional height then allows the contained and compressed air to escape around the bend in the pipe1 suddenly relieving the pressure and allowing the water to enter the pipe from under the bell readily4 ,thus the siphon starts and continues to flow until the water level falls so that the air is drawn in under the bell4 ,that stops the action of the siphon and the tank fills again4 ,these siphons are generally sold in two pieces1 the cast iron bell and the curved pipe being the factory product4 ,at the plant they have to be set in place1 generally bedded in concrete and properly connected with the outlet pipe4 ,for a small installation a three-inch or four-inch siphon is ample1 and will cost1 delivered1 from #aj to #ae1 depending on the freight4 ,illustration3 ,,fig4 #bj4--,van ,vranken ,automatic ,siphon4 ,fig4 #bb shows two siphons with auxiliary air-pressure chambers installed in the same chamber for the purpose of automatically diverting the flow from one bed to another4 ,this may be done more simply by installing two ordinary siphons of the ,miller or similar type4 ,if one of these siphons is filled half full when the tank is empty1 that siphon will discharge first because of the amount of water already present in the ,u-shaped tube4 ,during the filling of the tank previous to its discharge1 the other siphon will partially fill1 so that when the tank begins to fill for the second time the second siphon is half full and the first nearly empty4 ,in this way alternate action is secured and the discharge takes place as often as the tanks fill4 ,illustration3 ,,fig4 #ba4--,miller ,automatic ,siphon4 ,illustration3 ,,fig4 #bb4--;,double ,alternating ,siphons of the ,miller ,type4 ,fig4 #bc shows three similar siphons installed with some auxiliary piping attached for the purpose of making the periodic discharge more positive4 ,these small auxiliary pipes are so put together that there is an auxiliary siphon passing under the edge of the bells4 ,when one siphon discharges1 the auxiliary siphon of the corresponding large siphon is filled with water1 and at the same time part of the water in the auxiliary siphon of the other is discharged1 so that it will be the first to operate at the next filling4 ,when the water is forced to the bottom of the small siphon1 it is blown out through the vent pipe1 and1 the air following1 the large siphon is started4 ,illustration3 ,,fig4 #bc4--,triple ,alternating ,siphons of the ,miller ,type4 ,illustration3 ,,fig4 #bd4--,single 8,merritt0 ,automatic ,siphon4 ,fig4 #bd shows an automatic discharging siphon made by the ,merritt ,company1 of ,camden1 ,n4 ,j41 and embodying a different principle4 ,the main discharge pipe is built in the form of a 8,u0 tube1 the longer leg containing an auxiliary small air pipe1 with a return bend at its lower end4 ,when the chamber starts to fill1 this small pipe bend or seal is filled with water1 so that the rising water confines and compresses air in both the large and small 8,u0 pipes4 ,in time1 and at any desired height1 determined by changing the relative lengths of the parts of the small pipe siphon1 the seal is broken and the air escaping draws air enough from the large pipe to start it in action4 ,the method has an advantage in that it requires no deep excavation1 and the mechanism can be set after the siphon chamber is built4 ,illustration3 ,,fig4 #be4--;,air-lock ,siphon for ,admitting and ,releasing ,sewage from each one of ,four ,beds in ,regular ,order4 ,fig4 #be shows a method of securing the alternate discharge of sewage by siphons whose action depends upon an air trap1 each siphon being of the type shown in ,fig4 #bd4 ,the installation of the figure is further complicated by the fact that it is arranged to discharge sewage from the four contact beds as well as to discharge sewage onto the beds4 ,the compartments1 and the piping connected therewith1 at the four corners operate to admit the sewage from the central channel onto the four beds in rotation4 ,the four square wells between the corner wells operate to empty those beds in turn into the pipe shown at the centre of the drawing1 the pipe leading to the nearest stream4 ,the operation may be described as follows3 ,sewage enters at the top of the drawing1 and from the inlet channel flows into the siphon channels marked ,a4 ,a#a is ready to discharge if bed ,no4 #d was the last one to fill1 since1 when that bed filled1 the small bell ,d#d forced the siphon ,a#a open4 ,sewage therefore flows through siphon ,a#a into bed ,no4 #a4 ,as the sewage level rises in bed ,no4 #a1 the outlet siphon from bed ,no4 #b1 ,g#b1 is locked by the air pipe from ,b#a so that bed ,no4 #b will be ready for the next dose4 ,also the air pipe from the bell ,h#a opens the siphon ,g#d1 and allows bed ,no4 #d to drain into the outlet drain4 ,also bell ,d#a1 when bed ,no4 #a is full1 opens the siphon ,a#b through the connecting air pipe so that bed ,no4 #b begins to fill as soon as bed ,no4 #a is full4 ,and finally bell ,c#a locks the siphon ,a#a1 and stops further flow into bed ,no4 #a4 ,the other beds operate in the same way in turn4 ,the manufacturers of siphons are always glad to advise prospective buyers of the proper arrangement of siphons and the details of placing1 with dimension sketches4 ,as a summary1 it may be pointed out that in any installation1 one of the three methods above described may be adopted4 #a4 ,a simple valve worked by hand may be adopted and the alternate distribution of the sewage regulated by choice of the several valves placed at the head of the several discharge pipes4 #b4 ,an automatic discharge mechanism may be installed which will operate regularly and intermittently1 but lacking any automatic selection of the bed onto which the discharge is to be made4 ,these siphons will discharge as often as the tank fills1 but the particular valve must be opened in order that the discharge may take place onto any one of the several beds4 #c4 ,an apparatus may be installed which will both discharge intermittently and will also automatically select different beds in turn onto which the discharge shall take place4 ,it may even discharge onto contact beds and also empty those beds1 entirely automatically4 ,which of these mechanisms shall be selected depends upon the amount of money available and on the value to be placed on the freedom from constant care which an automatic installation gives4 ,not that a sewage-disposal plant may be ignored because an automatic mechanism has been installed4 ,no machine is infallible1 and sewerage machinery may give out or stop working just as that for any other purpose4 ,but instead of a daily routine of duties which may not be interrupted1 by means of automatic apparatus one may avoid everything except casual inspections and periodic cleaning4 ,,chapter ,,iv ,,sub-,,surface ,,irrigation ,the disposal of sewage by the method of sub-surface irrigation1 sometimes known as the ,waring system1 consists in its distribution by means of open jointed tiling over a comparatively large area of soil and at a depth of a few inches beneath the ground surface4 ,the sewage should first be passed through settling tanks to remove as much as practicable of the suspended matters contained in it1 as explained in the chapter on settling tanks4 ,the partially clarified effluent from the settling tank should then be collected in a dosing chamber1 or separate compartment of the settling tank1 and discharged intermittently1 preferably by means of a siphon1 into the sub-surface irrigation system4 ,this intermittency of discharge of accumulated quantities of effluent is necessary for an even distribution of the effluent throughout the entire system of sub-surface tiling1 and for a continuous and successful operation of the system as a whole4 ,it has been found necessary1 also1 to alternate the discharge of effluent from the dosing or siphon chamber over different portions of the irrigation area4 ,one siphon is all that is necessary to install in the siphon chamber for sub-surface irrigation systems1 and if the settling tank has two compartments1 as shown in ,fig4 #c1 ,chapter ,,ii1 the single siphon would be placed in the centre of the chamber4 ,the principle involved in this method of sewage purification is that of any general method of sewage reduction in whatever form carried on1 namely1 its oxidation or nitrification4 ,this oxidation1 or breaking down of the organic matter in the sewage1 is accomplished in this case1 as in the case of intermittent sand filters1 contact beds1 and sprinkling filters1 through the agency of bacterial action4 ,householders have long been familiar with the fact that although solids contained in sewage may have been discharged for long periods of time into a cesspool1 the latter1 if located in dry1 porous soil1 did not seem to become filled with the solid residue4 ,this is due to the liquefaction of the solid matter in the sewage after its discharge into the cesspool1 and to the seepage and bacterial reduction of the liquid matter in the surrounding soil4 ,to replace the cesspool and eliminate the insanitary conditions which1 in most instances1 result from its use1 other methods have been devised which utilize the agencies of nature to the best advantage4 ,thus the sedimentation and1 in some cases1 the liquefaction of the solid matters in sewage are carried on in specially designed settling tanks which are easily cleaned and which provide for greater efficiency in settling out suspended matters than the cesspool4 ,similarly1 the filtration of liquids from cesspools through the soil is replaced by the scientific method of sub-surface irrigation1 which is much more efficient in three distinct ways3 7#a7 the limited seepage area represented by the walls of the cesspool is increased many times by distributing the effluent from the settling tank over a large area of soil in a system of sub-surface tiling2 7#b7 the bacterial reduction is more effective1 since it has been found that the bacterial action necessary to purify sewage takes place in the upper layers of the soil and is almost absent at depths of five feet or more2 7#c7 the soil is given an opportunity to rest and to dry out by alternately using different portions of the sub-surface irrigation system4 ,in the cesspool the seepage of the effluent and whatever bacterial action takes place in the surrounding soil must go on continuously1 which often results in clogging of the soil and overflowing of the cesspool4 ,the purification and final disposition of sewage by means of sub-surface irrigation is the method best adapted to the single residence1 and oftentimes to the hotel or institution1 if soil conditions are favorable and proper area is available4 ,this system requires less oversight in its operation than the various forms of artificial filters4 ,furthermore1 the sewage is entirely hidden from sight after it leaves the settling tank1 and this is usually desirable near private residences and on the grounds of country homes1 country clubs1 and summer hotels4 ,also1 where the sewage must be treated in close proximity to a residence or hotel or at a point on the windward side of a residence1 this method1 more effectually than any other1 precludes the possibility of a nuisance resulting from the operation carried on1 since the settling-tank effluent is at no point exposed directly to the air4 ,furthermore1 its cost is less than that of other works for final treatment of sewage1 and1 finally1 the system is more easily installed4 ,the method is in reality modified broad irrigation1 but the sub-surface irrigation field can be utilized much more effectively and with considerably less attention than a broad irrigation area1 and1 as noted above1 is less liable to be the cause of a nuisance or to be the means of spreading infectious disease through the agencies of flies and other insects4 ,if an area of sandy soil is available on which to locate the sub-surface irrigation field1 if the settling tank and siphon chamber have been correctly built1 and if the sub-surface tiling system has been properly laid1 the success of the system is well assured4 ,on the other hand1 failure is certain if either broad irrigation or sub-surface irrigation methods of sewage disposal are attempted on stiff1 impervious clay soils4 ,between the ranges of porosity of soil represented by these limits there are many soils in which sewage may be successfully disposed of by sub-surface irrigation4 ,a sandy or gravelly loam will1 without question1 successfully care for sewage effluent when such effluent is properly distributed by sub-surface tiling1 and even in a rather heavy soil the effluent from a settling tank may often be disposed of satisfactorily by providing for a greater length of sub-surface tiling per person served by the settling tank than that which would suffice in the more porous soils4 ,however1 if the soil is very heavy so that surface water does not readily seep away1 or if the ground-water level is within two or three feet of the surface1 this method is not suitable and some form of filter1 described in the succeeding chapter1 should be used for final treatment of sewage4 ,when soil conditions and the area available are favorable to this method and such a system is to be installed1 the irrigation area selected should be at the point where the ground-water level is lowest1 and this will generally be on a plateau or bench at the head of a slope of ground4 ,the relative elevation of the ground surface should1 of course1 be low enough to insure operating head or fall to operate the siphon in the chamber adjoining the settling tank and to distribute the effluent by gravity to the sub-surface tiling4 ,if the soil is composed of loose gravel1 or lies over a limestone or shale formation1 the location of the irrigation area should be selected with a view to preventing the contamination of any wells or springs which may exist on the premises1--that is1 the area should be on lower ground1 and as far removed from wells as is convenient4 ,as will be explained later1 the length of sub-surface tiling necessary to receive a given quantity of sewage effluent should vary1 within certain limits1 with the character and porosity of the soil1 thus requiring larger quantities of effluent to be delivered from the siphon or dosing chamber in the case of the more compact soils4 ,also the size of this chamber should be determined with reference to the number of sections into which the sub-surface tiling system is divided4 ,,table ,,ii ,,for ,,use ,,in ,,the ,,construction ,,of ,,sub-,,surface ,,irrigation ,,systems ,,in ,,sandy ,,or ,,very ,,porous ,,soils ,dimensions given are for inside measurement4 ,number ,total ,no4 of ,mean ,mean ,depth ,diameter ,dis- ,distance of ,length ,sect- ,width ,length of of charging from ,per- of ions in of of ,siphon ,siphon ,depth or,roof to sons #c-;inch ,sub- ,siphon ,siphon ,chamber 7,inch- ,maximum ,top of ,served ,sub- surface,chamber,chamber from es74 ,depth of ,wall by surface,system47,feet747,feet74,roof of ,effluentbetween ,sewer4,tiling4 ,tank above ,settling 7,feet74 ,lower ,tank and ,edge of ,siphon ,siphon ,chamber ,bell 7,inch- 7,inch- es74 es74 #d #adj #bb #b #b #d #c #ac #ab #h #bhj #bb #f #b #f #b #d #c #ac #ab #ab #dbj #bb #f #d #b #d #c #ac #ab #ae #ebe #bc #f #d #b #d #c #ac #ab #be #hge #bc #d #c #b #e #bc #ab #ce #abbe #bc #h #d #f #c #b #e #bc #ab #ej #agej #bd #f #c #b #e #bc #ab #ge #bfbe #bc #f #c #b #e #bc #af #ajj #cejj #bd #g #c #b #e #bc #af #abe #dcge #ce #f #h #c #b #e #bc #af #aej #ebej #cg #h #c #b #e #bc #af #age #fabe #cg #f #h #c #i #f #cj #af #bjj #gjjj #ch #h #c #i #f #cj #ah ,,table ,,iii ,,for ,,use ,,in ,,the ,,construction ,,of ,,sub-,,surface ,,irrigation ,,systems ,,in ,,the ,,heavier ,,loams 7,,not ,,clay ,,or ,,hardpan7 ,dimensions given are for inside measurements4 ,number ,total ,no4 of ,mean ,mean ,depth ,diameter ,dis- ,distance of ,length ,sect- ,width ,length of of charging from ,per- of ions in of of ,siphon ,siphon ,depth or,roof to sons #c-;inch ,sub- ,siphon ,siphon ,chamber 7,inch- ,maximum ,top of ,served ,sub- surface,chamber,chamber from es74 ,depth of ,wall by surface,system47,feet747,feet74,roof of ,effluentbetween ,sewer4,tiling4 ,tank above ,settling 7,feet74 ,lower ,tank and ,edge of ,siphon ,siphon ,chamber ,bell 7,inch- 7,inch- es74 es74 #d #cjj #b #b #e #c #b #d #c #ac #ab #h #fjj #b #c #e #b #d #c #ac #ab #ab #ijj #b #d #e #b #d #c #ac #ab #ae #aabe #b #d #f #f #b #d #c #ac #ab #be #ahge #b #d #f #c #b #e #bc #ab #ce #bfbe #b #d #d #f #c #b #e #bc #af #ej #cgej #b #d #f #f #c #b #e #bc #af #ge #efbe #b #f #g #c #b #e #bc #af #ajj #gejj #b #g #h #c #b #e #bc #af #abe #icge #c #h #aj #c #i #f #cj #bj #aej #aabej #c #i #ab #c #i #f #cj #bj #age #acabe #caj #ab #d #b #h #ce #bj #bjj #aejjj #caa #ab #d #b #h #ce #bj ,the dimensions of siphon chambers to effectively deliver the effluent in proper volumes to the sub-surface irrigation system are given in the following tables1 which indicate widths of siphon chambers to agree in general with the widths of the settling tanks to serve a given number of persons1 as shown in ,chapter ,,ii4 ,these tables of dimensions for siphon chambers provide for two different capacities where the same number of persons are served by the sewer1 depending on the total lengths of sub-surface tiling required1 which in turn depend on the character of the soil in which the sub-surface system is laid4 ,the tables provide for a division of the sub-surface tiling system into two parts up to a system for #ajj persons1 and into three parts for a greater number of persons4 ,these tables also show the total length of lateral distributing tiling in the sub-surface irrigation system necessary to distribute over a sufficient area at the irrigation field1 in both sandy soils and in the heavier loams1 the various quantities of sewage to be treated in the different-sized tanks and discharged from the siphon chambers4 ,the tables also indicate the diameter of the siphon and the discharging depth of each siphon4 ,as discussed in ,chapter ,,iii1 the siphon1 in discharging1 may draw upon the upper #d to #h inches of sewage in the settling tank without interfering with the efficiency of the tank4 ,the dimensions of siphon chambers for #ge or more persons in ,table ,,ii1 and for #ce or more persons in ,table ,,iii 7see page #ei71 provide for such a draught upon the settling-tank contents of from #d to #h inches when the siphon discharges4 ,this will decrease the cost of the plant somewhat and provide for a more efficient form of siphon chamber4 ,the last column in each table provides for the proper height of dividing-wall between the settling tank and siphon chamber to allow the drawing down of the settling-tank contents as noted above4 ,illustration3 ,,fig4 #bf4--,plan and ,section of ,sub-surface ,irrigation ,system4 ,illustration3 ,,fig4 #bg4--,plan and ,section of a ,portion of a ,sub-surface ,irrigation ,system4 ,the sub-surface irrigation or distributing system consists of a main carrier or effluent sewer leading away from the siphon chamber to the irrigation field1 of two or more branches of this main carrier1 and of parallel lines of lateral distributing tiling extending at intervals of #d to #f feet from the branch carriers1 or1 in some locations1 from each side of the branch carriers4 ,the frontispiece shows the relation between the several portions of a sub-surface irrigation system4 ,the house sewer is shown leading to the settling tank1 and from the siphon chamber adjoining the settling tank the main carrier or effluent sewer is shown leading to a diverting manhole from which the effluent is carried at each discharge of the siphon to the lateral lines of sub-surface tiling by the two branch carriers4 ,fig4 #bf shows in plan and section a sub-surface irrigation system4 ,the section1 which is drawn to a larger scale than the plan1 shows the settling tank and the adjoining siphon chamber4 ,from this siphon chamber the effluent sewer carries the discharge from the siphon to the diverting manhole1 at which point the effluent is diverted to the different portions of the sub-surface tiling4 ,in ,fig4 #bg is shown in plan the diverting manhole and a small portion of the sub-surface tiling system together with a section through the diverting manhole and one of the lines of distributing tiling4 ,the main carrier should be of vitrified tile sewer pipe with cemented joints1 and should always have two or more branches at the irrigation field in order to allow the use of different portions of the field in turn for three days or a week at a time1 thus allowing one of the portions of the field to be resting for corresponding periods4 ,the branch carriers should be of vitrified tile also1 and should have cemented joints4 ,if the diameter of the siphon is #e inches1 the main carrier should be of #h-;inch vitrified tile with a fall of at least #f inches per #ajj feet in order to quickly carry the dose from the siphon chamber to the several lines of sub-surface tiling forming the distributing system4 ,with #c-;inch siphons1 a #f-;inch main carrier may be used1 but the gradient or fall of the main carrier should then be at least #ab inches per #ajj feet1 owing to the smaller capacity of the #f-;inch pipe4 ,in placing the siphon in position1 when the siphon chamber is being built1 care should be taken to see that the trap or ,u-shaped pipe is set plumb or in a vertical position4 ,concrete should then be placed around the siphon to hold it in proper position and at the proper height1 and the trap should be filled with water before the bell is placed in position4 ,the bell should then be placed in position over the long leg of the trap to prevent the materials used in construction from being dropped into the siphon4 ,the siphon should be set so that the lower edge of the bell1 or of that portion of the bell under which the effluent is to flow1 is three inches above the floor of the siphon chamber4 ,illustration3 ,,fig4 #bh4--,y-,branch of ,vitrified ,tile ,pipe4 ,in laying the distributing system1 every second or third length of the branch carriers1 according to the porosity of the soil and the spacing of the lines of distributing tiling1 should consist of a ,y-branch 7see ,fig4 #bh71 to which a one-eighth bend 7see ,fig4 #bi7 should be fitted if the lines of lateral tiling are to be laid at right angles to the main carriers1 as shown in ,fig4 #bg2 or the lateral tiling may be fitted directly to the ,y-branch if the lateral lines are to be led away from the carrier at an angle of #de1 as shown in ,fig4 #cj4 ,the ,y should branch from the lower portion of the pipe1 as shown in ,fig4 #bh4 ,illustration3 ,,fig4 #bi--;,eighth ,bend of ,vitrified ,tile ,pipe4 ,illustration3 ,,fig4 #cj4--,sub-surface ,tiling4 ,the lateral tiling should be of three-inch agricultural tile 7see ,fig4 #ca71 laid with a space of one-quarter inch between each length and with a piece of tar paper or a half-collar of larger diameter pipe1 as shown in ,fig4 #cb1 placed over the joints to prevent clogging of the pipe with earth4 ,in the heavier soils the lateral lines of sub-surface tiling are sometimes set in trenches eight to fourteen inches deep and about twelve inches wide1 filled with broken stone or gravel placed around the tiling to within two or three inches of the ground surface1 as shown in ,fig4 #cb4 ,this allows the effluent to seep away more readily1 but while of advantage in those soils the provision is not necessary in the more porous soils4 ,illustration3 ,,fig4 #ca4--,photograph of ,tile laid as if for ,sewage ,disposal4 ,it is generally found that a sufficient length of sub-surface tiling should be laid to provide for not more than one to three gallons of effluent per day for each linear foot of tiling4 ,in sandy soils there should be at least thirty to forty feet of tiling for each person served by the sewer1 with six feet of space between the lines of tiling4 ,this length per person should be increased up to seventy or eighty feet for the more compact sandy or gravelly loams1 or the lighter clay loams1 with the lateral tiling spaced four feet apart4 ,it is not considered feasible to attempt to dispose of sewage by sub-surface irrigation in soils which will not care for effluent when the greater lengths of tiling per person1 as stated above1 will not prevent the appearance of effluent on the surface4 ,if1 however1 after the installation of a sub-surface system in a rather heavy soil1 it is found that proper seepage of the effluent does not occur1 the lateral branches may sometimes be lengthened and the system then found to operate satisfactorily4 ,illustration3 ,,fig4 #cb4--,sub-surface ,tiling with ,broken ,stone or ,gravel ,surrounding ,pipe4 ,the lines of lateral tiling should be laid with the invert1 or bottom of the pipe1 inside1 from six inches to one foot below the surface1 as shown in ,fig4 #bg4 ,they should be parallel with the contours or at right angles with the slope of the field1 and should have a gradient or fall of one-sixteenth of an inch to the foot when laid in sandy soil or sandy loam1 and of not more than one thirty-second of an inch to the foot when laid in the heavier loams4 ,to obtain such gradients for the sub-surface tiling it is sometimes necessary to lay out the trenches along irregular or curved lines1 as shown in ,fig4 #cc4 ,the tiling should be laid near the surface1 as stated1 and never deeper than twelve inches4 ,the temperature of the sewage will prevent its freezing even in very severe winter weather1 especially when the ground is covered with snow4 ,illustration3 ,,fig4 #cc4--,sub-surface ,system on ,irregular ,ground4 ,to provide for diverting the flow from the siphon chamber first into one of the two portions into which the sub-surface system is divided1 and then1 after an interval of three days or a week1 into the other portion of the system1 at the point where the main carrier is to branch1 a ten-inch iron pipe casting 7see ,fig4 #cd71 with its lower portion forming the body of a double ,y-branch of six-inch or eight-inch pipe1 may be placed1 having a swinging blade or gate attached inside in a vertical position4 ,when1 for example1 the effluent has been passed for a week into section ,b of the sub-surface system1 the gate ,c1 shown in ,fig4 #cd1 may be swung to the dotted position and the effluent1 at each discharge of the siphon chamber1 will then pass through the branch carrier ,a to section ,a of the sub-surface system2 or a double ,y-branch of iron pipe 7see ,fig4 #ce7 or a cross may be placed at this point on the main carrier when there are to be three sections of the sub-surface system1 and valves may be placed on the three branches of the main carrier thus formed to permit of alternately shutting off the flow to the various sections of the sub-surface tiling system 7see also ,fig4 #cj74 ,perhaps the simplest and most serviceable device1 however1 for alternately resting different portions of the irrigation field is a diverting manhole with stop planks or wooden sluices sliding in grooves in the concrete walls or in a wooden frame1 as shown in ,fig4 #bg4 7,see also ,fig4 #dc1 ,chapter ,v47 ,where the ground-water level is not very deep below the surface1 or a clay or hardpan stratum occurs at a depth of a few feet1 it is advisable to underdrain the irrigation field by lines of open-jointed tiling laid at right angles to the lateral distributing tiling and spaced about fifteen feet apart4 7,see ,fig4 #cf47 ,illustration3 ,,fig4 #cd4--,special ,casting of ,double ,y-,branch with ,swinging ,gate4 ,illustration3 ,,fig4 #ce4--;,double ,y-,branch with ,valves on ,branches of ,main ,carrier4 ,these underdrains should be placed at least four feet below the surface1 and inspection pipes should be placed over the outlets of the underdrains or at the points where they discharge into a main underdrain1 in order to afford opportunity to determine if all portions of the irrigation field are properly caring for the effluent4 ,to provide for the placing of the inspection pipes1 a length of vitrified tile with a ,tee may be placed on each line of underdrain tiling near its junction with the main underdrain4 ,on this ,tee1 two or three lengths of vitrified tile may be set1 reaching to the ground surface and provided with a removable wooden cover or a vitrified tile cap4 ,this provision for inspection is necessary where underdrains must be laid and where the pollution of a stream is to be prevented1 since it is often found that through the activities of burrowing animals direct outlets from the distributing tiling to the underdrains are formed and the final effluent is therefore not sufficiently purified by seepage through the soil4 ,it is desirable for this reason to omit the underdrains when possible1 and in some instances a blind ditch may be constructed around two or three sides of the field in order to intercept the ground-water flow and to lower the ground-water level at the field1 thus better insuring proper seepage of the effluent distributed by the sub-surface tiling4 ,illustration3 ,,fig4 #cf4--,sub-surface ,tiling ,system with ,underdrains4 ,the essential features of the sub-surface irrigation system of sewage disposal have been outlined above1 and it may be said that this method is especially adapted to the residence or single house4 ,the method may be employed with success to dispose of sewage from country clubs and summer hotels1 provided the soil conditions are favorable and proper areas may be utilized4 ,in these cases the comparatively short period during each year in which the system is in use and the resulting long periods of rest give opportunity for a recuperation of the soil and permit the use of this system in comparatively large installations where1 under continuous operation1 a different method of disposal would be indicated4 ,it should be borne in mind1 however1 that when any doubt arises as to the suitability of the soil to care for sewage by this method1 and especially where considerable expense would be involved in the installation of the system1 competent engineering advice should be sought by property owners before the installation is undertaken4 ,in fact1 it is advisable in the case of all large plants of this type to employ the services of a sanitary engineer to lay out the system1 since the matter of accurate gradients and proper operating arrangements then becomes very essential to the success of the undertaking4 ,while it is not generally advisable to arrange for the disposal of sewage by sub-surface irrigation when the number of persons served by the sewer exceeds two hundred1 this method will be found a most satisfactory one if the general conditions at any point are favorable to its use as heretofore described1 and in such cases the adoption of this system is strongly recommended to the owners of residences1 summer camps1 summer hotels and boarding-houses1 and to the managers of moderate-sized institutions and of country clubs who must meet the problem of properly disposing of sewage on their own premises4 ,,chapter ,v ,,sewage ,,filters ,it has been shown that the selection of the type of plant best suited to solve the sewage-disposal problem at any given place depends on several factors and can be safely made only after a consideration and study of such local conditions as the character of the soil1 the area available1 the presence and nearness to the surface of ground water1 and the local topographical conditions4 ,if sub-surface irrigation is not feasible1 when1 for instance1 the soil is nearly impervious to water or when1 in the case of a wet soil1 adequate underdrainage is not possible1 some form of artificial filter must be constructed to complete the reduction of the sewage where the effluent from the settling tank may not properly be discharged directly into a stream4 ,if such a filter is to be constructed1 the kind most suitable depends1 in turn1 upon several factors1 such as the degree of purification to be attained1 the suitability of the available areas or locations for the different types of filters1 the operating head or fall available1 and the relative cost of the sand1 gravel1 broken stone1 or furnace slag which may be used as material for the filter bed4 ,with respect to the degree of purification of sewage that is desired it may be said that1 of the three general methods of sewage purification1 namely1 intermittent sand filtration1 treatment in contact beds1 and filtration through sprinkling or trickling filters1 the first method produces the most highly purified effluent4 ,such an effluent1 if from a properly constructed and operated sand filter1 may generally be considered sufficiently purified to allow its discharge into a stream1 even if the stream is subsequently used as a source of potable water supply4 ,in some instances1 however1 subsequent sterilization or disinfection of the effluent may be required1 particularly if the waterworks intake is relatively near the point of discharge from the sewage filter1 or if the flow of the stream is small in comparison with the sewage flow4 ,however1 if a stream used as a source of potable water supply receives the effluent from a properly operated sand filter1 the further safeguarding of the quality of the water should generally be accomplished by filtration or sterilization of the water supply1 or both4 ,in many cases the local conditions are such that contact beds or sprinkling filters may be constructed more easily or more economically than sand filters and1 at the same time1 the lesser efficiency of the contact bed or the sprinkling filter1 owing to the fact that the stream is not used for water supply1 may not preclude the adoption of these latter types of plants4 ,however1 where natural deposits of sand of not too finely divided particles occur or where such sand may be readily procured1 intermittent sand filters are most satisfactory for the final treatment of sewage4 ,,intermittent ,,sand ,,filters ,the agencies employed in purifying sewage by intermittent sand filtration involve its oxidation1 or nitrification by bacterial action1 while the mechanical straining effected by its passage through the sand plays a very small part in its reduction4 ,where natural deposits of sand of suitable quality occur1 sand filters are constructed by levelling off definite areas of sand and making embankments eighteen inches high to enclose these areas1 the embankments being generally formed of the surface loam and subsoil which must usually be removed in order to expose the sand layer4 ,there should be from three to five beds prepared in order to provide for alternating the discharge of the effluent from the settling tank over different portions of the filtration area and thus to provide resting periods for each bed while in operation4 ,also1 the preparation of several equal areas permits discontinuing the use of any single area for several days or a week at a time in order to allow it to dry out and permanently retain its filtering capacity4 ,in ,fig4 #cg is shown a view of a set of sand-filter beds arranged in terraces on sloping ground1 the embankments being formed by the material excavated to uncover the natural sand layer4 ,illustration3 ,,fig4 #cg4--,view of ,sand-filter ,beds for ,village in ,massachusetts4 ,the proper number of beds and the area of each bed corresponding to the number of persons to be served by the sewer are given in ,table ,,iv4 ,this table also gives the required dimensions of siphon chambers 7assuming that this chamber forms a separate compartment of the settling tank7 for the capacities necessary in order that the effluent may be distributed in proper quantities over each bed or over each pair of beds1 as in the case of plants serving two hundred or more persons4 ,the widths of siphon chambers given correspond in general with the widths of settling tanks given in ,table ,i4 ,as in ,table ,,iii1 the dimensions of siphon chambers given are based on a drawing down of the effluent in the tank when the siphons discharge1 amounting to from four to eight inches4 ,the last column in the table gives the space which should be left between the roof of the tank and the top of the dividing wall between the settling tank and the siphon chamber to provide for this draught upon the settling-tank contents4 ,it will be seen that no draught upon the contents of the settling tank when the siphons discharge is arranged for in the case of tanks serving from four to twenty-five persons4 ,,table ,,iv ,,for ,,use ,,in ,,constructing ,,intermittent ,,sand ,,filters ,persons ,no4 of ,area of ,mean ,width ,diameter ,distance ,served by ,beds4 ,each ,bed and ,length of ,siphonfrom ,roof ,sewer4 7,square of ,siphon 7,inches74 of ,feet74 ,chamber ,settling 7,feet74 ,tank to ,top of ,wall between ,settling ,tank and ,siphon ,chamber 7,inches74 #d #c #fj #c #c #c #ab #h #c #abj #c #e #c #ab #ab #c #ahj #d #e #c #ab #ae #c #bbd #d #f4e #c #ab #be #c #cej #d #f #e #ab #ce #c #dhj #d4e #e #e #af #ej #c #ffj #e #f #e #af #ge #c #ajjj #f #g #e #ah #ajj #c #acbj #g #h #e #ah #abe #c #affj #e4e #h #f #bj #aej #c #bjjj #h #h #f #bj #age #c #bccj #h #i #f #bj #bjj #e #afjj #h #ab #h #bj #bej #e #bjjj #aj4e #ab #h #bj #cjj #e #bdjj #ab #ac #h #bj #cej #e #bhjj #ac #ad #h #bj #djj #e #cbjj #ac #ag #h #bj #dej #e #cfjj #ac #ai #h #bj #ejj #e #djjj #ac #ba #h #bj ,the siphons in each instance should be so placed that the lower edge of the bell of the siphon will be at a distance below the roof of the tank equal to twelve inches plus the drawing depth or discharging depth of a siphon of the diameter indicated4 ,there should be three inches of space between the siphon bell and the floor of the chamber4 ,the discharging depths of siphons as used in forming ,tables #b1 #c1 #d1 and #e are as follows3 ,diameter of ,siphon4 ,discharging ,depth4 #c inches #ac inches #e inches #bc inches #f inches #cj inches #h inches #ce inches #aj inches #fj inches #ab inches #gb inches ,if the siphons installed are larger or smaller than those shown in these tables1 or if the particular make of siphon purchased has the same diameter but a different discharging depth1 proper allowance must be made in proportioning the size of the dosing chamber4 ,in order to quickly convey the dose from the siphon chamber to the filter beds at the rate at which the siphon discharges1 the sewer from the siphon chamber should be of proper size and should have a sufficient gradient4 ,for instance1 with a #c-;inch siphon the sewer should be #f inches in diameter1 with a gradient or fall of at least #ab inches per #ajj feet2 with a #e-;inch siphon1 the sewer should be #h inches in diameter1 with a gradient of at least #f inches in #ajj feet2 with a #f-;inch siphon1 the diameter of the sewer should be #h inches1 and should have a gradient of at least #ab inches per #ajj feet1 or #aj inches with a gradient of at least #c inches per #ajj feet2 with an #h-;inch siphon1 #ab inches1 with a gradient of at least #ab inches per #ajj feet4 ,sewage is sometimes applied directly to the beds without treatment in settling tanks1 generally1 in such cases1 after having been screened to remove the larger suspended matters1 but it is decidedly preferable in the case of the smaller plants under discussion to pass the sewage first through settling tanks1 as in the method of sub-surface irrigation4 ,therefore1 the areas of beds given in the table are for sewage which has been passed through settling tanks4 ,it is even necessary1 in the case of sand filters for institutions where considerable grease and soaps are contained in the sewage1 to provide grease traps through which the sewage must pass before it reaches the settling tank4 ,the effluent from the tank should be discharged intermittently by means of a dosing chamber and siphon and should be distributed quickly over the surface of the bed as uniformly as possible4 ,this is generally accomplished in the case of the larger beds by laying on the surface of the bed1 wooden troughs1 with short branches1 as shown in ,figs4 #ch and #ci4 ,a detail of a portion of these distributing troughs is given in ,fig4 #dj4 ,this view shows the hinged gates which are used to effect a proportionate division of the flow of the various branches of the main trough4 ,the view also shows the slots in the sides of the troughs which allow the sewage to flow out onto the bed4 ,illustration3 ,,fig4 #ch4--,layout for ,intermittent ,sand ,filtration4 ,if the ground-water level is within three feet of the surface at any time1 or if the sand is very fine and contains a slight proportion of clay1 underdrains should be laid at depths of four feet to prevent the beds from becoming waterlogged4 ,illustration3 ,,fig4 #ci4--;,intermittent ,sand-filtration ,beds4 ,where sand deposits do not occur at a point suitable for the location of the disposal plant1 but where sand may be procured at a reasonable cost1 the beds may be formed artificially similar to the natural sand beds heretofore described1 but should not be less than three feet deep4 ,it is generally necessary in the case of artificially constructed sand filters to provide underdrains as described below4 ,two views of such an artificial sand filter are shown by ,figs4 #da and #db4 ,in ,fig4 #da the settling tank and siphon chamber may be seen1 situated between two of the four beds composing the filter4 ,in ,fig4 #db is shown a nearer view of one of the beds with the distributing trough and its branches on the surface of the bed4 ,this bed1 of the four composing the filter1 was not in operation at the time the photograph was taken4 ,illustration3 ,,fig4 #dj4--,portion of ,distributing ,troughs for ,sand ,filters4 ,in ,fig4 #ch is shown a sand filter layout with three beds4 ,in this drawing are shown the sewer leading from the house1 the settling tank1 the siphon chamber1 in which are placed two siphons1 the effluent sewers1 and the diverting manhole1 from which three pipe lines convey the sewage to the filter beds4 ,in ,fig4 #ci is shown also a view of the three filter beds1 one of the beds being shown in section4 ,figs4 #dc and #dd show a plan and view of the diverting manhole4 ,where sand must be carted in to form the filters1 the embankments to retain the sand should generally be formed by excavating for a depth of two feet the whole area upon which the beds are to be placed4 ,the material thus excavated will usually be sufficient to form the embankments4 ,the embankments should usually be at least two feet wide on top and should have side slopes of one and a half to one2 that is1 the bottom width of the embankment should be two feet plus three times the height4 ,in clay soils the pits for the filter beds may be excavated with the sides vertical1 or nearly so4 ,the bottom of each bed1 as it is prepared for the placing of the sand which is to compose the filter1 should slope slightly from the sides toward the centre line of the bed4 ,illustration3 ,,fig4 #da4 ,where the character of the underlying strata of soil or the presence of ground water requires that sand filters1 whether natural or artificial1 should be underdrained1 this may be accomplished by laying a longitudinal main drain through the centre of the bed at a depth of at least three or four feet below the surface1 with branches each way at intervals of about fifteen feet4 ,the main underdrain should be six inches in diameter1 of agricultural tile or of vitrified sewer pipe1 laid with open joints1 and should have a fall of at least six inches per hundred feet4 ,the branches may be of three-inch agricultural tile4 ,illustration3 ,,fig4 #db4 ,illustration3 ,,fig4 #dc4--,view of ,diverting ,manhole4 ,in large installations for cities and villages it is usual to install either plural alternating siphons or apparatus known as sewage feeds1 by means of which the contents of the dosing chamber are discharged upon the different beds in rotation1 there generally being four or five beds constructed in each unit4 ,this requires a separate siphon or sewage feed for each bed1 and entails considerable expense4 ,however1 for smaller plants such as are now being considered1 two ordinary siphons may be placed in the same dosing chamber as described in ,chapter ,,iii1 and so primed as to discharge alternately4 ,then1 by means of a diverting manhole or chamber through which the dose must pass1 the effluent may be diverted onto two beds in rotation1 allowing a third bed to rest1 or1 if there are five beds1 it may be diverted onto two pairs of beds in rotation1 allowing a fifth bed to rest4 ,for instance1 in the case of five beds1 a diverting manhole may be constructed as shown in ,fig4 #de1 and arrangements may be made to couple bed ,no4 #c with ,no4 #b or ,no4 #d1 allowing bed ,no4 #a or ,no4 #e to rest by means of the stop-plank to cut off the flow to either of these beds1 as shown in the illustration4 ,then1 when bed ,no4 #c is to be rested1 stop-planks ,a and ,b are both closed1 and the stop-planks against all pipe outlets are raised4 ,if it is desired to throw bed ,no4 #a out of use1 the stop-plank is placed against the end of the pipe leading to this bed1 stop-plank ,a is raised1 and stop-plank ,b is lowered4 ,one siphon will then discharge onto beds ,nos4 #d and #e1 and with the next filling of the siphon chamber the second siphon will discharge onto beds ,nos4 #b and #c4 ,by a proper combination of the stop-plank positions1 any two sets of two beds each may receive alternately the discharge from the siphon chamber while the remaining single bed may be left resting4 ,the method for operating the beds in rotation described above may1 of course1 be easily applied when only three beds are constructed4 ,a provision for allowing one bed to be thrown out of use for a week or so at a time is very necessary for the reasons stated above4 ,illustration3 ,,fig4 #dd4--,plan of ,diverting ,manhole4 ,at intervals of several weeks it will be found necessary to break up the surface of each bed by raking or else to remove a thin coating of clogging material4 ,this should be done after the bed has been rested and dried out1 when the surface matting may be taken off without removing much sand4 ,to provide for operating the beds in winter1 in the late fall1 before the ground has frozen1 ridges and furrows should be formed on the surface of the beds1 similar to those shown in ,fig4 #ea4 ,the furrows should be two or three feet apart and eight to twelve inches deep4 ,then when effluent is discharged onto the beds in freezing weather1 as it fills the furrows1 an ice roof will gradually form1 spanning the furrows and protecting the sides and bottoms of the furrows from freezing1 especially if a snowfall occurs before severe weather sets in4 ,it will sometimes be found necessary1 especially with small beds that are well underdrained1 to provide board coverings for the furrows to take the place of the natural ice roofs4 ,illustration3 ,,fig4 #de4--;,five-way ,diverting ,manhole4 ,the effluent from the tank should be discharged in such quantities as to flood the entire bed to a depth of from one to two inches1 except that some of this effluent will immediately begin to seep into the bed4 ,respecting the quality and relative fineness of sand suitable for sewage filters1 it should be noted that certain empirical methods of measurement have been developed for use in comparing the size and uniformity of particles of various sands4 ,these measures are 7#a7 the 8effective size10 and 7#b7 the 8uniformity coefficient40 ,the 8effective size0 is the size of sand particle expressed in millimetres compared to which ten per cent by weight of the particles in the sample is finer4 ,the 8uniformity coefficient0 is the ratio of the size of grain which has sixty per cent of the sample finer than itself to the size which has ten per cent finer than itself4 ,concerning the grades of sand through which sewage may be successfully and properly treated by intermittent filtration1 it has been found that the 8effective size0 should not be less than 4#bj of a millimetre1 nor greater than 4#ej of a millimetre1 and the 8uniformity coefficient0 should generally be from #a4e to #c4j1 when sewage is applied at the usual rate4 ,if1 however1 the sand is clean and sharp1 but has an 8effective size0 somewhat smaller than the limit above stated1 it may sometimes be found suitable4 ,in the case of any sewage-disposal project of considerable magnitude1 where any doubt exists as to the suitability of the sand available for use in sand filters1 analyses of representative samples of the sand should be arranged for1 and competent engineering advice should be sought before any large outlay is incurred4 ,in general1 however1 it may be said that any clean1 sharp sand suitable for building use is suitable for sand-filter beds in any situation4 ,obviously1 the coarseness of the sand plays no part in its suitability as a filtering medium if the sand occurs in a natural bed and underdrains are not necessary1 since no question of the discharging of an unpurified effluent would ordinarily arise in such cases4 ,,contact ,,beds ,the treatment of sewage in contact beds consists in distributing the effluent from settling tanks over beds of broken stone1 furnace slag1 or other similar material contained in water-tight compartments and allowing the beds to fill so that the spaces between the filtering material will be filled with the sewage effluent4 ,these beds are so arranged that the effluent is held in contact with the filtering material for a fixed interval of time and then1 usually by means of special siphons called 8timed siphons10 or other automatic devices1 it is discharged from the beds onto sand filters for further treatment1 or into streams1 as the case may be4 ,the process involves1 as in intermittent sand filtration1 the nitrifying or oxidizing agencies of bacterial action1 and differs from intermittent filtration and from treatment of sewage on sprinkling filters principally in the fact that the flow of effluent through the beds is arrested and the liquid sewage held in contact with the filtering material1 as noted above4 ,much smaller areas of filter beds are required than in the case of sand filters1 and for this reason this form of filter will often be found preferable4 ,the conditions which result in its selection are usually either the unsuitable character of the soil or the presence of ground water1 making the installation of sub-surface irrigation systems impracticable2 or the absence of sand deposits or the high cost in any locality of sand suitable for sand-filtration beds1 making their construction difficult or expensive4 ,the walls and floor of a contact bed are generally constructed of concrete1 and the filter should be rectangular in form1 as it is easier to distribute the effluent uniformly over a bed of this shape4 ,the details given in ,chapter ,,ii for constructing the walls and floors of settling tanks will serve as a general guide in the construction of contact beds4 ,the real work of the contact filter is carried on during the period of 8resting empty10 that is1 after the effluent has been withdrawn from the bed4 ,while the effluent fills the beds1 much of the suspended solid matter1 together with a large proportion of the bacteria contained in the sewage1 adheres to a gelatinous film which has formed on the surfaces of the stones or other materials forming the beds4 ,this interval of 8resting full0 should usually be about two hours4 ,then1 when the liquid portion is withdrawn from the bed1 air is drawn in between the stones1 enabling the nitrifying or arobic bacteria to do their work of breaking down both the suspended and the partially dissolved organic matters which have been contained in the sewage and which have adhered to the filter material4 ,it is believed1 that some oxidation of that portion of the organic matter which is in true solution is also accomplished when the effluent passes over the gelatinous covering of the stones by reason of the oxygen which has been absorbed by this covering4 ,the interval when the bed is 8resting empty0 should be considerably longer than the combined intervals when the bed is filling1 8resting full10 and emptying4 ,for this reason there should be a series of from three to five beds in order that it will not be necessary to turn the effluent from the settling tank continuously onto one bed1 which would result in the clogging of this bed with suspended matters4 ,the additional third 7or fifth7 bed also gives opportunity for allowing each bed in turn to be thrown out of use for intervals of a week or so at a time1 which is also necessary to keep the beds up to their proper efficiency and obviate the necessity of cleaning or renewing the filter material oftener than once in seven or eight years4 ,illustration3 ,,plan ,,of ,,sewage ,,disposal ,,works ,,for ,,mr4 ,,charles ,l4 ,a4 ,,whitney ,,albany1 ,n4,y4 ,in ,fig4 #df is shown in plan and section a sewage-disposal plant for the residence of ,mr4 ,charles ,l4 ,a4 ,whitney1 of ,albany1 ,n4 ,y41 consisting of a settling tank1 dosing chamber1 and contact beds4 ,this plant is designed to serve twenty-five persons1 although the settling tanks have a capacity for double the amount of sewage on the usual basis of design4 ,the depth of filtering material in the beds should preferably be four or five feet1 although1 where operating head or fall is limited1 this depth may be decreased to three feet4 ,the floor of the bed should slope toward the outlet end at a rate of about one-eighth of an inch per foot4 ,various materials are used to form the body of the filter1 such as broken stone1 coke1 broken brick1 and furnace slag1 but the material used should not be such as will disintegrate readily1 and for this reason broken limestone1 from one-half inch to one and one-half inches in size1 with perhaps two-inch stones for the bottom six inches of the bed surrounding the underdrains1 is most suitable for small plants4 ,these underdrains should be constructed of horse-shoe tiling1 and in the case of beds more than eight or ten feet wide should preferably be laid with short branches reaching from a main drain laid along the centre of the floor of the bed2 or these drains may be laid in parallel lines1 as shown in ,fig4 #df4 ,in order to alternate the discharge of effluent from the settling tank onto different beds in turn and to provide for more uniformly distributing the effluent over all portions of the bed1 the settling-tank effluent should be collected as in the other methods of disposal described1 in a siphon or dosing chamber1 from which1 by means of alternating siphons1 it may be delivered to the proper bed4 ,in the case of a group of three beds or five beds1 diverting chambers with stop-planks1 similar to those described in connection with intermittent sand filters1 may be provided to allow the throwing out of use of each of the beds in turn for a week or so at a time4 ,in the smaller plants accommodating up to one hundred and fifty persons1 it is hardly necessary to provide for more than three beds1 thus allowing opportunity for each one to rest for one week in every three to six weeks1 which will result in a temporary increase of fifty per cent in the rate of application of effluent to the remaining beds4 ,in the case of the larger plants1 especially if they are to be operated continuously1 it is better to construct five beds so that two pairs of two beds each may be used alternately1 leaving one bed1 or twenty per cent of the total area1 out of use4 ,this will result in an increase of but twenty-five per cent in the rate of application of effluent to the four beds in use4 ,with the usual rates of operation for contact beds1 one filling per day of the beds will result1 and1 if the dosing of the beds is carried on as above and as described in the portion of this chapter dealing with the dosing of intermittent sand filters1 but two siphons in the dosing tank1 constituting double alternating siphons1 will be necessary4 ,such an arrangement will eliminate the necessity of installing plural alternating siphons consisting of three or more siphons1 the cost of which is not warranted in connection with small plants1 since the double alternating siphons will insure proper operation of the beds at much less cost4 ,of course1 in the larger plants where two beds are dosed at each discharge of a siphon1 a larger siphon chamber is necessary with the two siphons1 but the extra cost of a larger siphon chamber would in most cases be more than offset by the increased cost of plural alternating siphons4 ,the main effluent carrier from the siphon chamber to each contact bed should discharge into a half-tile carrier1 with branches1 laid on the surface of the contact bed1 as shown in ,fig4 #df4 ,each contact bed should be provided at the outlet end with a 8timed0 siphon set in a separate chamber of two compartments1 as shown in the drawing4 ,the diameter of the timed siphons should generally be that of the next larger size than that indicated for the dosing-chamber siphons4 ,as shown in the illustration1 where only three beds are necessary1 the third timed siphon may be dispensed with if arrangements are made to permit the use of one siphon for discharging either the middle or the outside bed on that side1 and to permit the use of the other siphon for discharging either the middle bed or the bed on the other side4 ,in such installations gates or valves must be placed on the outlets of the contact beds to prevent the filling of the bed that is out of use by back flow from the timed siphon chamber used to discharge the adjacent bed4 ,the cost of contact beds is considerably greater than the cost of intermittent sand filters1 especially when sand of proper quality is available1 but their construction is advised in many cases where sub-surface irrigation is not feasible1 where the premises are subject to overflow or the ground-water level is high1 and where it is not practicable to construct sand filters4 ,in the following table are given the proper number of units or beds for contact filters of different-sized installations1 together with the required area of each filter1 the depth of the filter medium in all beds being four feet4 ,the table also shows the dimensions of the siphon chamber adjacent to the settling tank and the diameter of the siphons necessary to discharge the effluent in proper volumes onto each contact bed1 or each pair of contact beds4 ,where it is necessary to decrease the depth of the contact beds to three and one-half or three feet1 owing to lack of operating head or fall1 a proportionate increase should be made in the area of each bed4 ,,table ,v ,,for ,,use ,,in ,,constructing ,,contact ,,beds ,persons ,no4 of ,area of ,mean ,width ,diameter ,distance from ,served by ,beds4 ,each ,bed and ,length of ,siphons ,roof of ,sewer4 7,square of ,siphon 7,inches74 ,settling ,tank ,feet74 ,chamber to ,top of ,wall 7,feet74 between ,settling ,tank and ,siphon ,chamber 7,inches74 #d #c #bjc #d4e #e #ab #h #c #djd #f4e #e #ab #ab #c #fj #f #g #e #ab #ae #c #gj #f #h #e #ab #be #c #ajj #f #h #f #af #ce #c #acj #g #i #f #af #ej #c #ahj #h4e #aj #f #af #ge #c #bhj #aj #aa #h #ah #ajj #c #cgj #ab #ab #h #ah #abe #c #dfj #ab #ad #h #bj #aej #c #eejab #af4e #h #bj #age #e #cij #ac #ad #aj #bj #bjj #e #ddj #ad #ae #aj #bj #bej #e #eej #ae #ah #aj #bj #cjj #e #ffj #ag #ai #aj #bj #cej #e #ggj #ah #ba #aj #bj #djj #e #hhj #ah #bd #aj #bj #dej #e #iij #bj #ba #ab #bj #ejj #e #aaaj #bj #bc #ab #bj ,in the above table1 as in the previous tables1 in indicating the height to which the dividing wall between the settling tank and siphon chamber should be carried1 allowance is made for a draught upon the contents of the settling tank at each discharge of a siphon of from four to eight inches4 ,in the discussion relating to siphon chambers in connection with the description of intermittent sand filters will be found the necessary details as to the discharging depths of siphons of different diameters and the necessary depths of the siphon chambers in which such siphons are to be placed4 ,the construction of contact beds will naturally be approached with hesitancy by property owners and others not familiar with such work1 and it is strongly recommended that where it is possible the services of a sanitary engineer be engaged to design and supervise the construction of a plant involving any considerable outlay1 unless it is felt that the descriptions and directions given above have afforded a clear understanding of the design and construction of this type of sewage-disposal works4 ,,sprinkling ,,filters ,one of the more recently developed methods of sewage disposal1--the sprinkling- or trickling-filter system1--has for its principal feature the thorough aration of the settling-tank effluent before its passage through the filter4 ,this filter1 like the contact filter1 is of the rapid1 coarse-grained type1 but in its operation resembles the process of intermittent sand filtration in that the sewage effluent passes through the filter continuously without being held in contact with the filtering material as in the contact bed4 ,the aration of the sewage effluent1 which very greatly aids the final process of nitrification or oxidation in the filter1 is accomplished by spraying the sewage effluent over the surface of the beds through a series of riser pipes with nozzles1 or allowing it to fall in fine streams on dash plates which cause it to sprinkle over the beds and thus to absorb oxygen from the air4 ,sprinkling filters produce an effluent with a considerably less degree of purification than sand filters1 but may in general be said to produce a more stable effluent1 that is1 one less liable to subsequent putrefaction than the effluent from contact beds4 ,furthermore1 with the usual depths of contact beds and sprinkling filters1 an area approximately four times greater is required to treat the same amount of sewage on contact beds than is necessary if sprinkling filters are constructed4 ,however1 since the effluent from sprinkling filters is much more turbid1 necessitating1 in most cases1 subsequent sedimentation before discharge2 since considerably greater operating head or fall is necessary2 and since their operation requires much more supervision1 the construction of sprinkling filters is not generally as advisable as contact beds for small installations1 especially in cold climates4 ,the construction of sprinkling filters as compared to contact filters differs principally in the size and depth of filtering material1 in the means provided for distributing the effluent over the beds1 and in the arrangements for draining the filter4 ,the depth of filtering material in a sprinkling filter is usually from five to ten feet1 preferably not less than eight feet4 ,the material for the filter is the same as that used for contact filters but the fragments should be from one to three inches in diameter4 ,instead of a system of tile underdrains on the floor of the filter1 a false floor of perforated tile1 rectangular in section1 or of half tile1 circular in section1 with drainage holes cut out along the sides1 should be laid over the entire floor of the filter4 ,as the settling-tank effluent is sprayed on the filter it passes downward between the spaces of the filtering material1 and reaching the floor of the filter is collected in a main drainage channel1 through which it passes to the outfall sewer1 and thence to the final settling tank or into the stream4 ,as with contact beds and sand filters1 intermittency of application of the effluent to the filter is essential for proper action of the filter1 and this is accomplished as in the other types of filters by means of automatic siphons placed in dosing tanks4 ,these tanks1 however1 are of special design in the case of sprinkling filters4 ,each siphon discharges into a main carrier of iron pipe which extends sometimes over the surface of the filter1 but generally along the floor of the filter4 ,the main carrier has branch pipes of smaller diameter extending at right angles nearly to the sides of the filter4 ,on these branches vertical riser pipes spaced about ten feet apart are connected1 and these riser pipes extend a few inches above the surface of the filter4 ,nozzles are fitted to the ends of the riser pipes by means of which the sewage effluent1 under pressure1 is sprinkled1 at short intervals1 in the form of a fine1 umbrella-shaped spray1 over the surface of the filter4 ,this results in a thorough aration of the effluent before it reaches the filtering material1 and makes this form of filter very effective4 ,illustration3 ,,fig4 #dg4--,view of ,sprinkling ,filter at ,danville1 ,pa41 in ,winter4 ,in ,fig4 #dg is shown a view of a sprinkling filter at ,danville1 ,pa41 operating when the temperature was #ad below zero4 ,it is generally believed1 however1 that in cold climates it is advisable to house small sprinkling filters4 ,owing to the rather complicated hydraulic features and the somewhat difficult engineering principles involved in the construction and operation of sprinkling or trickling filters1 it is not deemed advisable to attempt to describe them in sufficient detail to furnish directions for their construction4 ,the design of a sprinkling-filter system for small as well as for large installations should always be entrusted to an engineer conversant with this line of sanitary engineering4 ,it is believed1 however1 that the description of such filters given above will aid those who are about to install sewage-disposal plants in the selection of the type of plant best suited to their particular needs and conforming to the conditions peculiar to their situation4 ,summarizing the foregoing descriptions and directions with reference to sewage filters1 it may be stated that where natural facilities for disposing of sewage by simpler methods do not exist1 the construction of a sewage filter of some one of the above described types offers a solution of every problem thus encountered4 ,it is well to repeat that sub-surface irrigation1 where feasible1 should be adopted1 and this will be the method indicated in a large majority of cases where small disposal plants are to be constructed4 ,the principal point to be remembered in connection with sewage filters is that their construction is but a good beginning1 and that their proper operation is very necessary to the success of the undertaking4 ,they constitute1 with the developed bacteria in the filter1 a rather sensitive mechanism capable of efficient work if properly handled1 but each filter unit must be carefully operated and must be regularly given extended periods of rest for the restoration of the void or open-space capacity of the filter1 and to provide for the necessary aration of the filtering material4 ,the peculiar action which takes place in a filter in the reduction of sewage1 and which is not even yet fully known1 is best evidenced by the fact that sewage filters1 especially of the coarse-grained type1 do not attain their highest efficiency until after several weeks or months of operation4 ,with a knowledge of these points1 it will be seen that there should be little divergence from accepted standards in the construction and operation of sewage filters if they are to prove satisfactory when installed4 ,,chapter ,,vi ,,broad ,,irrigation ,for many years it has seemed to thoughtful persons that permitting sewage1 either from single houses or from larger communities1 to be turned into streams was a mistaken policy because of the waste of manurial elements involved4 ,it has long been understood that1 in order to maintain the fertility of the soil1 a constant application of fertilizers was necessary1 and1 while undoubtedly many farms are managed without any such repeated applications1 the more scientific and modern farmer believes to-day that the frequent and abundant use of fertilizer is the foundation of his success4 ,in ordinary sewage there exists a certain amount of fertilizing elements4 ,two prominent ,english chemists1 not many years ago1 proved by their analyses that in ordinary sewage there existed the essential elements of a good fertilizer to the value of #b per year for each person contributing to that sewage4 ,other chemists1 working at the problem in other ways1 have reached about the same result1 and there can be little doubt of their accuracy if the fertilizing elements alone are considered4 ,in applying these figures to the sewage of a city the difficulty has always been that the fertilizing elements have been so thoroughly covered up with the large volume of water present in the sewage that it has been practically impossible to separate them from the water4 ,thus1 in a city of #ajj1jjj persons1 the fertilizer in the sewage might1 indeed1 be worth #bjj1jjj1 but to realize this amount it must be separated from the #aj1jjj1jjj gallons of water--a task which is so tremendous1 if not impossible1 as to make the value of the fertilizer of no account4 ,in those parts of the country where the water itself has a value1 as in the irrigated lands of the ,west1 the fertilizing elements of the sewage would be added to the value of the water1 so that sewage used for irrigation would be worth not merely the value of the water alone1 but also the value of the fertilizer present in that water4 ,another difficulty in making use of the combined water and fertilizer is that the large amount of water involves a large area of land and suitable soil1 on which irrigation may be practised1 in the immediate vicinity of the city4 ,this combination of agricultural soil of suitable texture at a suitable price for farming operations is so seldom found that this in itself usually precludes any application of the use of sewage for irrigation4 ,in the case of the sewage from a single house1 however1 the possibility of making use both of the water and the fertilizer in sewage is not so difficult4 ,recent writers on irrigation have pointed out that1 while irrigation of late years has made most headway in the semi-arid districts of the ,west1 there are many opportunities for its successful and profitable utilization in the ,east1 and ,mr4 ,lute ,wilcox1 in a recent book on irrigation1 says3 8,the farmer who has a soil containing an abundance of all the needed elements in a proper state of fineness cannot but deem himself happy if he have always ready at hand the means of readily and cheaply supplying all the water needed by his soil and growing crops1 just when and in just such quantities as are needed4 ,happier still may he be when he realizes that he need have no #8off years'1 and he knows that the waters he admits to his fields at will are freighted with rich fertilizing elements usually far more valuable to the growing crops than any that he can purchase and apply at a costly rate--a cost that makes serious inroads upon the profits of the majority of farmers cultivating the worn-out or deteriorated soils in the older ,states year by year4 ,fertilizers are already needed for the most profitable culture on many farms in ,iowa1 ,minnesota1 ,eastern ,kansas1 and ,nebraska1 in ,missouri1 and in all ,states east of those named40 ,perhaps the greatest uncertainty in the matter of farming is the available water coming from the clouds4 ,in one year the rainfall may come at the proper time to moisten the seed and to insure a rapid germination4 ,these early rains may be followed by showers at proper intervals to supply the little rootlets with the necessary moisture so that the growth of the plant may be constant and vigorous4 ,during the ripening season the rains may be withheld so that the harvest is insured under the most favorable conditions4 ,in other years1 however1 the spring rains may be so continuous as to cause the seeds to rot1 requiring a second sowing4 ,then the rains may fail so that the seeds either fail to germinate1 or at best produce scattered and imperfect growths4 ,at the time of harvest storm may follow storm1 so that the harvesting of those plants which have developed is made almost impossible4 ,irrigation tends in part to correct these difficulties1 since it furnishes the soil with the needed water at times when the lack of rain would cause an entire failure in future growth4 ,irrigation1 of course1 cannot prevent rainfall1 and it may be that after a copious soaking of the ground with the irrigating water a heavy rain may follow1 resulting in an excess of moisture as bad for the ground as none at all4 ,the possibility of irrigation cannot prevent excessive rains at the time of harvest1 but the advantages of being able to control the soil moisture during the period of growth are more than enough to counterbalance any possible disadvantages4 ,during the summer months evaporation is very high1 the dryness of the air and the high temperature combining to draw moisture from the soil in considerable quantity4 ,then1 too1 the plants themselves1 while absorbing moisture from their roots1 evaporate moisture through their leaves1 and agricultural stations have made extensive studies on the amount of this evaporation from different plants4 ,the teaching of it all is that the amount of water which can be utilized by the soil1 not merely for the sake of the growth of the plants themselves1 but to make up for the demands of evaporation1 is very high4 ,mr4 ,newell1 of the ,united ,states ,geological ,survey1 points out that while the amount of water required for raising crops varies according to soil and other conditions1 yet a large quantity is required to maintain the soil in such a degree of saturation as to best promote the vitality of the plant life4 ,he shows that for each ton of hay raised upon an acre1 from three hundred to five hundred tons of water must be furnished either by rainfall or by artificial means4 ,in other words1 since water covering an acre to a depth of one inch weighs about one hundred and thirteen tons1 it would be necessary to cover an acre to a depth of from three to five inches if that acre produced one ton of hay4 ,from actual conditions1 he shows that it has been necessary1 in order to produce five tons of barley hay per acre1 to provide an amount of water which would cover the acre to a depth of twenty inches4 ,although his figures have special reference to the semi-arid regions of the ,west they furnish a guide for the amount of water which may profitably be used in addition to the rainfall1 which1 in the summer months1 may be practically nothing even in the ,east4 ,from three to six inches in depth each month is his estimate of the needed water for successful crop growing1 the difference depending upon the character of the soil1 more being required in sandy soils and less where the texture is finer4 ,the sewage from an ordinary household1 on the basis of #cj gallons per head per day1 amounts to #ahj gallons per day1 or about #e1djj gallons per month1 or #gbj cubic feet4 ,this amount of water would cover an acre of ground to a depth of a little less than one-fourth of an inch1 and it is plain that in order to have the sewage of a single house furnish the necessary amount of water for successful crop growing1 the area required is only about one-twelfth of an acre1 or an area about #fj feet square4 ,in the early days of the ,english experiments with the disposal of sewage1 great stress was laid on the value of the manurial elements in sewage1 and many tests were made as to the capacity of various soils for absorbing the moisture present in sewage4 ,one of the most enthusiastic advocates of this method of disposing of sewage was ,mr4 ,j4 ,bailey ,denton1 who was able to act as engineer for many installations of various sorts4 ,as a result of his experience he came to the conclusion that while the area depended upon the character of the soil1 and while with the most suitable soil a very large amount of water might be taken care of1 under ordinary conditions it was safest to so design the works that no possibility of overloading the soil with water could exist4 ,he places the limits of population1 the sewage from whom would be cared for on an acre1 between #a1jjj persons per acre and #ajj persons per acre4 ,more recent experience1 together with constant observation of farms established in the early period of the practice1 indicates that the higher value is too great1 and that where agricultural processes alone are considered1 #ajj persons per acre is a suitable maximum value for irrigation on sandy loam1 and that #dj persons per acre is a suitable number where the soil is inclined toward density and fine texture4 ,six persons in a household would1 according to ,mr4 ,denton1 require from one-seventh to one-seventeenth of an acre4 ,the amount1 indicated by the computations made earlier1 indicated one-twelfth of an acre for the same number of persons4 ,the practical agreement of the two methods of computing the area necessary thus makes it possible to determine in either way the amount of land needed on a given farm for disposing of the household sewage4 ,the effect of sewage irrigation has been found to be most astonishing so far as the increased yield of the soil goes4 ,some years ago1 in order to determine just the effect of the addition of sewage to ordinary farm land1 a certain field of five acres was divided into four equal parts4 ,the four fields were treated as follows3 ,field ,no4 #a received no sewage4 ,field ,no4 #b received six inches of sewage over its entire area on each of five successive months4 ,field ,no4 #c received twelve inches of sewage on each of five successive months4 ,field ,no4 #d received eighteen inches of sewage on each of five successive months4 ,the following table shows the results of three successive years' experiments at the sewage farm referred to at ,rugby1 ,england1 the figures being the number of pounds of green grass cut from the fields4 ,,five-,,acre ,,field ,,without ,,sewage4 ,,with ,,sewage4 ,lot #a4 ,lot #b4 ,lot #c4 ,lot #d4 #bj1had #cc1bdd #fj1fjb #gc1efd #ah1bid #fb1ead #gg1bii #ga1gff #aa1jfi #di1hea #gh1bca #hj1ida ,aver4 #af1gbe #dh1ecf #gb1jdd #gf1dcd ,it will be noticed that1 whereas without sewage the amount of green grass was about eight tons on an acre and a quarter in the field1 from lot ,no4 #b twenty-four tons were cut1 from lot ,no4 #c thirty-six tons1 and from lot ,no4 #d thirty-eight tons4 ,evidently the amount of sewage applied did not proportionately increase the yield in lots #c and #d1 and it may be said that a depth of sewage or water of more than twelve inches per acre has1 in general1 been found to be not merely unnecessary1 but undesirable4 ,the table does not show the number of cuttings made during the season1 but the custom on the farm is to cut frequently1 at intervals of perhaps two or three weeks1 no time being given for curing the hay4 ,the crops suitable for growth on irrigated fields have been found by experience to be grass and root crops1 such as beets1 turnips1 and the like4 ,mr4 ,wilcox1 in writing of the requirements of different plants1 suggests celery as a garden crop that needs a great deal of water4 ,beets1 carrots1 parsnips1 and turnips are favorite plants for irrigated fields4 ,cabbage and cauliflower are benefited by abundant irrigation during the first part of their growth1 but after the heads of the cabbage plants are half-formed1 further excessive use of water is undesirable4 ,the use of irrigating water in orchards has been practised with great success not only in the recent irrigation areas of the ,west1 but along the ,hudson ,river and in ,new ,england4 ,the size of the fruit is increased by irrigation1 and it is said that the bloom is much improved4 ,,methods ,,of ,,applying ,,the ,,water ,in distributing the water or sewage over the soil in the case of a single house1 no elaborate methods are required4 ,in the case of large farms supplied with sewage from a considerable population1 elaborate systems of piping or open-channel conduits are required1 and the problem of working out and adjusting the necessary sizes and grades becomes a complicated matter for which engineering knowledge and experience are required4 ,but for the small flow which comes from individual houses and from the small area involved1 no such elaborate preparations are required4 ,the essence of the distribution consists in carrying the water onto the field to be irrigated at such a low velocity that no surface soil or valuable manures are washed away2 and in adjusting the volume of the flow and the requirements of the soil1 there are three characteristic conditions which require different treatments4 ,in the first place1 the area may be practically level and the crop raised may be either grass or grain4 ,in such a case the sewage should be led onto the field which may properly be enclosed on four sides with a low1 that is1 six to twelve inches1 earth-dike1 and at each irrigation the field may be flooded about two inches deep4 ,the next irrigation would probably not be required for a week1 so that this method requires a number of beds to be worked one after another and1 except where the soil is very dense1 so much so that percolation is very slow1 this method is not suitable because of the slow rate at which the sewage is delivered4 ,the second method of distribution1 and one more suitable for the conditions under discussion1 is to lay out the field in parallel beds from three to six feet wide and from forty to one hundred feet long4 ,these beds are separated by furrows into which the sewage is discharged4 ,if the grade of these furrows is properly adjusted to the porosity of the soil1 that is1 made about six inches in one hundred feet for open1 sandy loam1 and about two inches in one hundred feet for fine1 clay loam1 the soil will absorb the needed moisture as the sewage flows over it and there should be no ponding or excess of water at any point of the field4 ,by dividing the field into three parts1 or in arranging the flow of sewage so that it enters only two or three furrows at a time1 the flow can be so changed from day to day as to furnish all parts of the area with the irrigating water1 and at the same time not overload and choke the soil particles4 ,on the beds may be planted and grown whatever vegetables are desired4 ,a good basis for determining the area and length of furrows required is to provide a length of thirty feet of furrow for each person of the household4 ,the total length thus obtained should not1 however1 be made continuous1 but should be arranged in three parts1 or in multiples of three1 so that one-third of the total length only may be used on any one day1 the other parts serving for other days1 so that a rotation is practised4 ,illustration3 ,,fig4 #dh4--;,distribution of ,sewage and ,arrangement of ,check ,levees on a ,hillside4 ,the third condition involves the application of the sewage to a steep slope1 and this may be treated in either one of two ways4 ,the sewage may be led to the top of the hill and allowed to flow1 for a short distance only1 over the surface on which1 presumably1 grass is to be grown4 ,if the length of the furrow is more than about a dozen feet1 the flowing stream acquires enough velocity to wash the surface and to form gullies4 ,to prevent this1 a secondary ditch or small bank is thrown up to arrest the flow4 ,the water is led out again from behind this ditch or bank at intervals1 to repeat the process further down the hill 7see ,fig4 #dh74 ,if the slope of the ground is moderate1 so that there is no tendency of the water to form gullies1 the water may be let out of the ditch at intervals and allowed to distribute itself over the field1 as shown in ,fig4 #di4 ,the water thus overflowing should be collected in a drain at the lower end of the slope1 and will be found suitably purified for discharge into any running stream not used for drinking purposes4 ,the occasional use of a shovel or hoe may be needed to change the flow of the water over the field if it is found that any tendency exists for definite channels to be formed4 ,illustration3 ,,fig4 #di4--;,distribution of ,sewage on a ,hillside of ,moderate ,slope4 ,in order to plant vegetables on such a hill1 small furrows may be made along the hill and laid out with great care so that the flow of sewage in the furrows shall be only at a slow velocity1 so slow that the soil can absorb the moisture as the water passes along4 ,by zigzagging this furrow back and forth down the hillside1 vegetation on the hill will receive the benefit of the water1 and if any of the sewage succeeds in reaching the bottom of the hill1 it will be so purified that it may be safely discharged into any depression or watercourse there found4 ,in the case of orchards1 irrigation is practised by flooding the ground around the tree1 being careful1 however1 to throw up a mound of earth around the tree so that no water comes within two feet of the tree itself4 ,fig4 #ej shows a ,western method of forming square beds1 each bed about twenty feet on a side1 with one tree at the centre4 ,furrows are also used to distribute the water1 a common practice followed being to being to have the furrow always under the extreme edge of the foliage1 thus discharging the water in the vicinity of the tender rootlets of the tree4 ,usually the furrow system is carried only in one direction1 so that the application of water by this method is not so complete as by the flooding method4 ,but for small volumes of water constantly applied1 it is probably more satisfactory4 ,fig4 #ea shows a grain field irrigated by the furrow method4 ,illustration3 ,,fig4 #ej4--,square ,beds for ,orchards ,according to ,some ,western ,practice4 ,in all cases where irrigation is practised1 stress is laid by those experienced in the matter on the necessity of cultivation of the soil in connection with the irrigation4 ,apparently1 there is a tendency for the surface layers1 with the application of water1 to cake or crust over the lower strata1 thus depriving the soil of the necessary air4 ,in order to break up this crust1 the soil must be continually worked1 either by a hoe or rake or some sort of horse cultivator4 ,where the ground is shaded1 as in the case of land covered with grass or grain1 the tendency to crust is not so marked1 but on cultivated land where root crops are grown the cultivator must be used regularly after each irrigation4 ,where the sewage is carried onto the field in furrows1 the soil in the furrow should be hoed at frequent intervals1 not only to break up the crust which deprives the soil of the air1 but in order to open the particles of soil for the reception of the irrigating-water4 ,illustration3 ,,fig4 #ea4--;,grain ,field in ,spring1 in ,process of ,irrigation4 ,it must also be remembered1 as has been pointed out before1 that the success of any method of applying sewage to soil depends upon the frequent change from bed to bed1 the actual time interval depending on the character of the soil4 ,if the soil is fine1 the same area may be used for a week at a time1 and then given two weeks' rest4 ,if the soil is more open1 this interval should be reduced1 and with very coarse particles it may be found desirable to shift the flow from one bed to another after an interval of a few hours only4 ,experience and careful observation on the moisture-carrying capacity of the bed is the best guide to the operation of sewage irrigation4 ,whether or not this method of disposing of the sewage of a single house is to be selected depends largely upon the slope of the ground from the house toward the garden4 ,it is not desirable to have sewage exposed to the air in the immediate vicinity of a dwelling-house4 ,rarely would any odors be generated to such an extent as to be offensive to the occupants of the house1 since the sewage sinks into the ground before putrefaction of the organic matter sets in and the exposed material left on the surface of the ground is of too attenuated a type to become offensive even if it does putrefy before drying4 ,there is1 however1 the danger of odors being formed where distribution is imperfect and where pools are allowed to form in the furrow4 ,there is also the danger of the transmission of disease germs from the sewage-irrigated field to the occupants of the house through the agency of flies4 ,health statistics of ,english farms show this danger to be a very remote one1 since the health of the workman on those farms is as good or better than the average throughout ,england4 ,but the possibility of infection exists and must not be overlooked4 ,no method of disposal requires so much and such constant care1 although the results show in the improved yield from the farm4 ,this method of broad irrigation is emphatically not the method to be used except where labor is adequate for proper soil cultivation and where this labor can be given constantly and ungrudgingly4 ,finally1 it must be pointed out that care should always be exercised to prevent irrigating sewage coming in direct contact with any of the soil produce4 ,certainly sewage should not be used to sprinkle over lettuce or celery or strawberries1 even if the yield is thereby increased4 ,undoubtedly any disease germs thus distributed over the fruits and vegetables would1 through the antiseptic action of the sunlight and air1 soon be destroyed1 but the very method of irrigation is repulsive1 and the danger1 while slight1 is sufficient to forbid that method of fertilizing4 ,no statistics1 however1 are available to show that cows eating sewage-irrigated grass are adversely affected in health1 and for years the practice of thus pasturing cows has been carried on in ,england4 ,for human beings1 however1 vegetables grown in soil that is separated from the sewage by a foot or more is the safer as well as more sthetic arrangement4 ,,chapter ,,vii ,,estimates ,,of ,,cost ,in order to estimate the cost of installing a sewage-disposal plant and of treating continuously the sewage from any residence1 certain fundamental assumptions are always necessary4 ,in the first place1 the unit cost of the manual labor which forms so large a part of the total cost of construction must be known for the particular time and place1 and perhaps no item in the cost of construction is so important as this4 ,in a great many small installations it may be excluded altogether1 since all the hand work required is contributed by the householder at such times as the other work of the place may allow1 without any additional cost4 ,in other places1 if a money value be placed on such labor1 it may be expressed in terms of the cost of a hired man whose rate of wages1 paid monthly1 in addition to board1 would be always less than if wages were paid to day laborers living at their own homes4 ,again1 in the southern part of the country labor may be had for #a4be a day1 whereas in the central portion of the ,united ,states it is necessary to pay #a4ge a day1 and in the extreme ,west from #b4jj to #c4jj a day for common labor4 ,often1 too1 the working day is of different length in different parts of the country4 ,in the estimates which follow1 labor is assumed to cost #a4fj for eight hours' work1 that is1 at the rate of twenty cents an hour4 ,if1 in adapting the estimates of this chapter to any particular installation1 the question of labor may be neglected because of the fact that the householder will himself do all the required work1 then the item of labor cost may be eliminated4 ,if other units than those here assumed are suitable for the particular locality where any plant is to be built1 then the labor item must be modified accordingly4 ,material4--,the cost of material always varies very greatly in different parts of the country4 ,this is partly because of different freight and other transportation rates between the factories where material is made up and the particular place where that material is to be used2 and partly because the profits made by the middleman increase as the material gets further and further away from the centres of civilization4 ,thus1 in a large city six-inch sewer pipe may be sold in such large quantities that the freight rate is low and the dealer is satisfied with a small profit on each foot of pipe4 ,in the country districts the dealer sells but little1 and feels that he must have a larger profit to compensate him for the expense of keeping the material on hand4 ,thus1 six-inch sewer pipe may be had at prices ranging from six cents up to sixteen cents per running foot1 depending on the store from which it is bought4 ,it is evident1 therefore1 that it will not be possible to name any unit price which will be generally applicable1 and it will be necessary for any intending builder to secure from local firms the unit prices from which his own individual estimate may be made up4 ,the following discussion1 however1 will indicate the items comprising the necessary estimate1 and will furnish an example by which the estimate sheet can be prepared4 ,laying ,sewers and ,drains4--,the main drain from the house to the sewage disposal plant is of five- or six-inch pipe generally1 the former being sufficiently large and a little cheaper than the six-inch pipe4 ,the latter has the advantage of size and consequent greater freedom from clogging4 ,the cost of five-inch pipe at a store in a village of any considerable size should be ten cents per foot1 and the cost of six-inch pipe twelve cents per foot4 ,this pipe weighs twelve and fifteen pounds per foot respectively1 and1 with an ordinary wagon1 fifty feet of six-inch pipe1 weighing about eight hundred pounds1 is a load2 if four trips a day are possible from the residence to the store and if the cost of the team is estimated at #d a day1 each trip will cost #a1 and each foot of pipe will cost two cents more for being hauled from the store to the grounds4 ,in laying the pipe1 cement and sand are necessary for joints4 ,for both kinds of pipe there is required about one cubic foot of mortar for each fifty joints1 the mortar being sufficient to fill the joints and to make a collar or ring outside4 ,in order to make this cubic foot of mortar1 half a bag of cement and half a cubic foot of sand will be required4 ,the cost of the cement out of the village store is about fifty cents a bag1 although in a small place it may be seventy-five cents1 or even one dollar4 ,if one were buying cement in large quantities1 a price as low as thirty cents a bag might be had4 ,if the cement is delivered in cloth bags1 a rebate of ten cents a bag is usually given if the bag is returned in good condition4 ,the cost of sand is usually dependent upon the cost of hauling4 ,it will require forty minutes to shovel one yard of sand into a wagon1 or at twenty cents an hour it would cost about fifteen cents4 ,the cost of shovelling sand through a screen depends upon the amount of material which has to be rejected1 since only a certain proportion of the sand is available for all that is shovelled4 ,the cost of this shovelling is again about fifteen cents per cubic yard of material shovelled1 and if one-third of it is coarse gravel which has to be rejected1 one and one-half yards would have to be screened for every yard of sand available1 and the cost would1 therefore1 be twenty cents for screening1 a total cost of sand in the wagon of thirty-five cents per yard4 ,if four loads of sand can be delivered per day1 with a cost of fifty cents per hour for team and driver1 the sand will cost #a4ce per yard on the grounds1 this amount being increased or decreased if the number of trips per day must be made less or more4 ,excavation4--,the cost of excavation depends on the character of the material and on the amount of water present1 the cost of pumping or bailing the latter1 if in large quantity1 adding materially to the cost of shovelling4 ,the material through which the trenches are driven may vary from a sand which can be shovelled without loosening1 to solid rock which must be blasted1 an intermediate condition of soil being known as hardpan and its excavation costing nearly as much time and effort as rock itself4 ,if the soil is sand1 into which a shovel or spade can be pushed without any picking of the material1 the cost1 as already stated1 will be about fifteen cents a cubic yard for shovelling1 and if the excavation is in trench and not more than six feet deep1 the entire trench can be excavated for seven and a half cents a lineal foot4 ,it is very unusual1 however1 to have conditions so favorable that such a low price can be counted on4 ,if the material requires picking1 instead of fifteen cents a cubic yard it will cost thirty cents a cubic yard1 and a trench two feet wide and six feet deep will cost fifteen cents a running foot instead of seven and a half cents4 ,if care is not taken at the start to throw the dirt well back1 it will be necessary to re-handle the dirt from the bottom of the trench1 throwing it back on the pile1 and this will add from five to ten cents a cubic yard1 depending on what proportion of the entire excavation has to be re-handled4 ,in the excavation for a tank1 it is quite possible that the entire material may have to be re-handled and the cost thus be increased by fifteen cents a cubic yard4 ,if the ground is very hard1 as when boulders and clay are intermixed1 it may require twice as much time for loosening as for shovelling1 in which case the cost of digging the trench will be forty-five cents a cubic yard1 or twenty-two and a half cents per lineal foot1 with five or ten cents added if the material has to be re-handled4 ,if the material is a loose sand or gravel1 the trench will probably require sheeting1 that is1 boards or planks on each side of the open trench with braces between1 in order to prevent caving of the banks4 ,if new lumber has to be purchased for this purpose and its cost added to the cost of excavation1 an additional sum per cubic yard or per lineal foot will be added1 somewhat in proportion to the total amount of excavation to be done4 ,finally1 if the soil through which the trench is being dug contains water1 it may be necessary to have one or two men continuously pumping during all the time that the excavation is going on1 and this also will add to the cost per cubic yard or per lineal foot of the trench4 ,refilling may be done by hand or may be done by a drag scraper at the end of a rope1 so that the team of horses may be on one side of the trench and draw into it from the other side the excavated material4 ,this costs only five cents per cubic yard4 ,if the dirt is thrown back by hand1 the cost will be that of shovelling1 namely1 about fifteen cents per cubic yard4 ,if the dirt has to be tamped in the trench1 the cost will then be that of another man1 and backfilling will often add thirty cents a cubic yard to the cost of excavation4 ,as a summary1 it may be said that excavation alone in earth may cost from fifteen cents to forty-five cents a cubic yard1 and that backfilling may add to this from five to thirty cents a cubic yard1 the entire cost1 therefore1 varying from twenty cents to seventy-five cents a cubic yard for excavation and backfilling together4 ,nor is it possible to be more definite in explaining the proper price to put on excavation since the character of the material and the nature of the excavation are of such importance in fixing that cost4 ,if the excavation is for a tank1 it is often possible to rig a derrick with a long arm on the side of the excavation and1 by means of a bucket1 transfer the excavated material from the hole to the bank cheaper than by repeated shovelling or by carrying out the dirt in a wheelbarrow4 ,wheelbarrow work is always expensive1 the cost of transporting earth in a wheelbarrow a distance of fifty feet being about ten cents a cubic yard4 ,sometimes a horse may be used to great advantage to lift the bucket and operate the derrick in place of a hand-worked windlass1 although the use of the horse is hardly worth while unless the excavation is more than ten feet deep4 ,the excavation for the trenches of a sub-surface irrigation system cannot be estimated on the same basis as for a larger trench4 ,more time is required proportionally in trimming and grading the sides and bottom1 so that the cost per cubic yard is much increased4 ,thus1 while such trenches contain about one cubic foot of earth per lineal foot1 and on the basis of twenty-seven cents per yard would cost only one cent per lineal foot to dig1 it is probable that1 under ordinary conditions1 this amount would be doubled4 ,the cost of underdrains must be made up from the cost of the pipe used and the cost of the necessary excavation4 ,in the bottom of artificial filter beds1 the latter amounts to little or nothing4 ,in natural filter beds1 the trenches are deeper and the cost of the underdrainage depends largely on this excavation cost4 ,the cost of the pipe varies from two to ten cents per foot1 depending on the kind of pipe used and its unit cost4 ,rock ,excavation4--,if the trench or the place for the tank is to be in rock1 the cost of excavation is much increased4 ,the rock must be drilled and blasting powder or dynamite used to loosen the material so that it can be thrown out later by hand4 ,in ordinary rock1 a man will drill from six inches to twelve inches of hole per hour1 that is1 the hole will cost from ten to twenty cents per lineal foot4 ,the depth of the hole determines the amount of rock loosened per charge4 ,if the holes are three feet deep1 about one-third of a cubic yard is loosened per hour1 while if the holes are five feet deep1 one cubic yard of rock is loosened per hour4 ,this indicates at once the economical advantage of deep holes compared with shallow ones4 ,in the first case1 nine lineal feet of hole would have to be drilled in order to get one cubic yard of rock1 nearly double the amount required where the hole is five feet deep4 ,usually the distance between the holes is made equal to the depth of the holes1 although in some rock the depth can1 with advantage1 be made greater than that distance4 ,if the rock is very loose and seamy1 deep holes may sometimes not be warranted1 because the effect of the blasting is taken up by the loose rock in such a way that the value of the explosive is not realized4 ,shallower holes1 more frequently blasted1 utilize the explosive gases more completely4 ,the kind of explosive which may be used varies from slow1 low-power black powder to rapid1 high-power nitro-glycerine1 the many forms of dynamite and high-grade powder in use being combinations of nitro-glycerine with some absorbent4 ,in most cases1 ordinary blasting powder is suitable for rock excavation in small quantity4 ,it lifts the rock rather than shatters it1 and is more convenient and safe to handle4 ,forty-per-cent dynamite is to be recommended where the rock is very seamy so that quick-acting explosive is essential1 and also where the rock is very hard1 so that black powder tends to blow out the hole rather than to shatter the rock4 ,the cost of forty-per-cent dynamite is about twenty cents per pound1 and the cost of powder is about twelve cents per pound4 ,on the average1 it may be assumed that it will require one pound of the former and one and a half pounds of the latter per cubic yard of ordinary rock excavated4 ,the cost of lifting the blasted material out of the trench will be at about the same rate as that of earth4 ,concrete4--,the walls of tanks made of concrete depend for their cost upon the cost of the material and the cost of the labor involved4 ,it is usually more economical to use gravel as the basis of the concrete if any is available1 and in order that the product may be of good quality it is always best to screen this gravel1 separating it into sand and stone4 ,the proper size of screen for this operation should be not greater than one-half-inch mesh4 ,the stone and sand can then be re-combined with the cement in the proportion of one part of cement to two and a half parts of sand to five parts of stone1 this mixture making a very strong and impervious combination4 ,the cost of this mixture depends chiefly on the length of haul for the gravel and on the natural grading of the material4 ,if the proportions required for concrete exist naturally in the bank or stream bed from which the gravel is to be obtained1 there is little or no waste involved in screening1 and the only cost is that of handling the material twice4 ,if1 on the other hand1 the amount of stone is inadequate1 it may be necessary to waste a good deal of the fine sand and enough material has to be shovelled to produce the required amount of coarse media4 ,assuming that the cost of shovelling the material from the stream bed is fifteen cents a cubic yard1 and that the haul is two miles1 so that four trips a day are made1 then the gravel can be delivered where it is to be converted into concrete at a cost of one dollar for hauling and thirty cents for shovelling1 while if the haul is only one mile1 so that eight trips a day can be made1 the cost will be eighty cents per cubic yard4 ,if any waste of gravel is necessary1 these costs will be increased correspondingly4 ,at the site of the proposed plant the sand and gravel must be mixed with the cement and carried to place4 ,it has been found by experience when the mixing is done thoroughly and by hand1 and when the resulting concrete can be shovelled directly behind the forms1 that the cost of the mixing and placing is about one dollar per cubic yard of concrete4 ,if the concrete has to be wheeled into place this cost will be added to4 ,in order to make a cubic yard of concrete1 it is necessary to have nearly one cubic yard of the coarse material1 whether this be rounded stones from a gravel bank or angular stones from a stone-crusher4 ,seven-eighths of a cubic yard of stone may be safely considered as necessary for a cubic yard of concrete4 ,to this must be added three-eighths of a cubic yard of sand for a one to two and a half to five mixture4 ,when this amount of stone and sand have been thoroughly mixed together1 four and a half bags of cement should be added4 ,inasmuch as the variation in sizes of the individual particles of rounded gravel is such that a dense concrete results naturally1 it is quite reasonable both to increase the amount of stone and decrease the amount of cement if that variation in size seems to be one which will produce a dense mixture4 ,thus one cubic yard of stone1 one-third cubic yard of sand1 and four bags of cement may be used and will1 under favorable conditions1 result in a good concrete4 ,in order to determine whether this latter combination is permissible on any particular piece of work1 a test may be made by thoroughly mixing the materials together in the proportions named and testing the volume of this mixture 7,b7 in a box of measured dimensions4 ,then the same volumes mixed together in the former proportions 7mixture ,a71 and tested in the same box will show the relative value by occupying either more or less space than the other mixture 7,b74 ,if less1 mixture ,a is a better one1 and should be used2 if more1 then the latter mixture1 ,b1 is the better one4 ,the amount of water required for mixing concrete depends upon the temperature of the outside air as well as upon the personal ideas of the person in charge of the mixing4 ,some builders like wet concrete and some like dry concrete4 ,it should be noticed1 however1 that wet concrete is cheaper because it requires little or no tamping4 ,wet concrete1 however1 should be spaded1 that is1 a spade forced down into the mixture1 particularly against the forms1 so that particles of air caught between the stones may escape1 and so that there may be no pockets between the stones into which the liquid cement mixture does not penetrate4 ,it is generally considered that about fifteen per cent of the volume of concrete is the necessary volume of water for the mixture4 ,this amounts to thirty gallons1 or a barrel of water1 to a yard of concrete1 although the sizes of barrels vary1 and a cement barrel would not be large enough1 and a road-oil barrel would be too large4 ,the cost of forms depends1 again1 on the cost of material and on the cost of labor4 ,rough lumber varies in price from twenty to forty dollars a thousand feet1 board measure1 delivered on the grounds1 and the cost of framing and placing it varies from eight to twenty dollars per thousand1 depending on the skill of the carpenters and on their daily wages4 ,in order to estimate the cost of the lumber required for building false work1 it is best to determine exactly the amount of lumber required1 and get the price from a lumber yard on that quantity4 ,ordinarily1 it is safe to say that a carpenter in building forms will be able to saw and nail in place #bej board feet per day1 so that1 knowing the amount of lumber to be used and the wages of the carpenter1 it will be easy to determine the cost of the forms as first set up4 ,they may be taken down and removed for the purpose of re-assembling in another place for about half the cost of placing originally1 and by carefully arranging to build the forms in panels or sections1 they may be removed by a carpenter at the rate of #d1jjj or #e1jjj board feet per day4 ,valves4--,in connection with a sewage-disposal plant1 valves are essential at many points4 ,at the entrance to the several parts of the settling tank1 flap valves are suitable to admit or keep out sewage from the several compartments4 ,gate valves are used on the by-pass lines and on connecting lines between the tank and the filter beds in order to be of service when it is occasionally necessary to clean the beds4 ,more simple valves may be used in manholes where a diversion of the flow is required and where perfect and complete water-tightness is not essential4 ,these valves may be made of plank1 sliding up and down in grooves left in the concrete walls for that purpose4 ,sludge valves may be made to fit in the bottom of the tank1 and depend for their water-tightness on the weight of the valve itself with the aid of a rubber packing which is placed between the valve and its setting4 ,the cost of these various kinds of valves cannot be given exactly1 since their cost depends upon freight and profit of the various commission men through whom the valves are ordered1 but1 generally speaking1 they will be found to differ but little from the costs given in the following table3 ,,table ,flap valve as shown in ,fig4 #af #e4jj ,gate valve 7iron bearings7 for #f-;inch pipe 7,fig4 #ac7 #bj4jj ,gate valve 7bronze bearings7 for #f-;inch pipe #cj4jj ,sludge valve as shown in ,fig4 #aj #d4jj ,iron slide valve as shown in ,fig4 #aa #ae4jj ,dosing ,devices4--,dosing devices referred to in ,chapter ,,iii are usually purchased directly from the manufacturer1 and while their cost varies a little1 depending upon the cost of freight1 an ordinary single automatic siphon may be estimated at #ae1 the difference in price varying a little with the different makes of siphon4 ,if an alternate discharge is required1 then two siphons must be installed1 by means of which alternate intermittency is secured1 the variation1 however1 being only from one to the other and back again to the first4 ,if a plural alternate discharge is to be used1 the cost may be estimated roughly for a #f-;inch siphon at from #ej to #ge for each unit1 this price including the necessary piping but not the cost of setting4 ,filling ,material4--,artificial sand filters require a sand of uniform size and one free from dirt4 ,these two requirements add very materially to the cost of sand1 since it is almost impossible to find a natural sand which fulfils the necessary requirements4 ,a few sections of the country are fortunate in having sand in the vicinity suitable for filtration purposes without any washing or screening4 ,such parts of the country1 however1 are limited to those where sand has been deposited by glacial action1 and is essentially silicious in character4 ,it is hopeless to expect to find suitable sand in the centre of ,new ,york ,state1 for example1 and even with washing and screening1 sand in this locality is far from being desirable4 ,it will be found1 further1 that after this undesirable sand is washed and screened the cost of the final product is so great that it is usually cheaper to use broken stone either as a filter or as a contact bed4 ,washing sand in small quantities is done by throwing the sand into a channel through which water is passing1 the sand being retained by a series of low partitions in the channel4 ,if the water enters the box or channel through a pipe at the bottom1 frequent entrance holes being provided along the sides and bottom of this pipe1 the sand is kept in a state of suspension1 the dirt more readily washed out1 and a much smaller amount of water used4 ,the cost of shovelling the sand into the washer and again out of the washer1 about thirty cents per cubic yard1 must be added to the original cost of the sand4 ,the cost of water1 if pumped by hand or by steam1 will be about ten cents per cubic yard of sand cleaned1 making the total cost about forty cents per cubic yard4 ,if only three-fourths of the unwashed sand is available for use1 then the cost of the final product is a little less than fifty cents per cubic yard4 ,the sand before being brought to the washer will have been sifted at an additional cost of perhaps thirty cents per cubic yard4 ,hauling from the bank to the washer1 or from the washer to the site of the disposal works1 or both1 if the water supply requires the washer to be placed at some distance from the sand bank1 will add from fifty cents to one dollar a yard to the costs already indicated4 ,it may generally be assumed that it will be impossible to put sand into an artificial filter for less than #a4ej a cubic yard1 and it may easily cost #b4ej a yard if the sand bank is at considerable distance from the site of the works4 ,broken stone in most parts of the country can now be bought from a stone-crushing plant4 ,if road construction has been in progress in the vicinity1 the contractor for the work has been obliged to open a quarry and set up a crushing-and-screening plant1 and it will generally be possible to buy broken stone from such a contractor at about fifty cents per cubic yard4 ,the cost of hauling and the cost of shovelling into the beds must be added to determine the cost of the stone in place4 ,sometimes it is cheaper to bring the stone from a distance by rail1 such stone costing about #a4be at the railroad station4 ,then the cost of hauling and shovelling must be added4 ,it will be noticed that the cost of stone does not differ materially from the cost of sand1 and since the amount of stone needed is only about one-quarter of the sand needed1 it is generally cheaper to build a stone bed4 ,the purification1 it will be remembered1 however1 is decidedly inferior4 ,finishing4--,there is always some slight expense necessary in finishing and cleaning up after any piece of construction work4 ,material left over has to be hauled away1 and in order to leave the plant in an attractive dress1 seeding or sodding the earth slopes is desirable4 ,it is even desirable to plant shrubbery around the edges of the beds1 partly as a screen and partly to minimize the offensive suggestions which seem to be inseparable from any plant dealing with sewage4 ,the cost of these final improvements may be as little or as much as the owner and builder chooses1 but it is urged that their value should not be overlooked4 ,the following table is given as a guide and help in putting together the various items that make up the total cost of a sewage-disposal plant4 ,each line should be carefully considered1 and if the item mentioned is to be used or paid for1 the amount in the last column should be filled out4 ,,table ,,of ,,items ,,on ,,which ,,to ,,base ,,estimate ,,of ,,cost ,,of ,,sewage-,,disposal ,,plant ,no4 ,cost of ,units ,excavation and ,refilling ,trenches in sandy soil1 shallow at per cu4 yd4 depth ,trenches in stiff soil1 shallow at per cu4 yd4 depth ,trenches in sandy soil1 deep cut at per cu4 yd4 ,trenches in stiff soil1 deep cut at per cu4 yd4 ,tank1 depth and soil duly at per cu4 yd4 considered ,beds1 depth and soil duly at per cu4 yd4 considered ,embankments between filter beds at per cu4 yd4 7additional cost7 ,trenches for sub-surface lines at per lin4 ft4 ,trenches for underdrains at per lin4 ft4 ,trenches for sludge disposal at per lin4 ft4 ,surfacing and ,finishing ,surface soil placed at per sq4 yd4 ,gravel in walks at per sq4 yd4 ,flowers and shrubbery ,total amount ,concrete ,work ,manholes on pipe lines at each ,settling tank1 bottom1 sides and at per cu4yd4 roof ,dosing tank1 in addition to at per cu4 yd4 settling tank ,manholes on sub-surface lines at per cu4 yd4 ,concrete in contact beds or at per cu4 yd4 filters ,concrete in protection wall at end at per cu4 yd4 of outfall ,pipe ,lines #e- or #f-;inch tile pipe 7laid71 at per lin4 ft4 house to disposal plant #f-;inch pipe used in disposal at per lin4 ft4 plant1 laid #f-;inch pipe from plant to outfall at per lin4 ft4 #f-;inch pipe for sludge line at per lin4 ft4 #f-;inch pipe for main underdrain at per lin4 ft4 #c-;inch agricultural tile in at per lin4 ft4 sub-surface disposal #d-;inch agricultural tile in at per lin4 ft4 underdrains #f-;inch specials1 bends1 tees1 at each etc41 in addition to cost of straight pipe #c-;inch specials1 bends1 tees1 at each etc41 in addition to cost of straight pipe ,cast-iron pipe at per lb4 ,cast-iron specials1 bends1 etc4 at per lb4 ,wooden troughs for surface at per #ajjj ft4 ,b4,m4 distribution1 in place ,filter ,material ,gravel filling around sub-surface at per cu4 yd4 tile1 placed ,sand filling for artificial filter at per cu4 yd4 beds ,broken stone for contact beds or at per cu4 yd4 for filters ,broken stone for sludge beds at per cu4 yd4 ,valves ,gate valves1 ,fig4 #ac at each ,flap valves1 ,fig4 #af at each ,slide valves1 ,fig4 #aa at each ,wooden slide valves at each ,sludge valves1 ,fig4 #aj at each ,tools ,shovels1 long or short handled at each ,picks at each ,wheelbarrows1 wooden or steel at each ,sieves for screening sand and at each gravel ,saws1 hammers1 and axes ,total amount ,lumber ,for sheeting and bracing2 rough at per #ajjj ft4 ,b4,m4 lumber ,for forms for concrete work1 sized at per #ajjj ft4 ,b4,m4 ,for runways1 staging and mixing at per #ajjj ft4 ,b4,m4 boards1 plank ,hardware ,nails for forms1 staging1 etc4 at per #ajj lbs4 ,bolts or wire for concrete forms at per lb4 ,iron ,work ,manhole frames and covers at per lb4 ,steps for manholes at per lb4 ,siphons ,flushing siphons for dosing tank at complete ,timed siphons for emptying contact at complete beds -------------------- ,total ,cost of ,maintenance4--,as to the cost of maintenance1 very little that is definite can be said4 ,sub-surface irrigation plants should require no expenditure except for the occasional cleaning of the sedimentation tank4 ,if this is emptied three times a year1 the labor needed would amount to about a half-day's time on each occasion for a family of ordinary size4 ,for sand filters1 either natural or artificial1 the tank must be emptied as with sub-surface irrigation1 and1 in addition1 the surface must be scraped occasionally1 and at the approach of winter furrows must be dug4 ,perhaps two days' time would be all that would be needed for a plant dealing with the sewage of a single family4 ,a broken-stone bed requires no attention for seven or eight years1 and then the stone has to be shovelled out1 washed1 and replaced4 ,in none of the installations is this excessive in comparison with the benefits received1 and it should not be considered a burden to expend this amount of time in maintaining so important a part of the household economy as the disposal of the household wastes in a sanitary manner4 ,it must not be forgotten1 however1 that no sewage-disposal plant is exempt from occasional break-down or accidents1 and that there must be a constant supervision exercised4 ,this supervision should not require much more time than above suggested1 but should be exercised for the purpose of correcting irregular flows or distribution before the value of the plant is utterly destroyed4 ,,index ,bacteria1 action of1 in reducing organic matter and sewage1 #f ,baffle boards in settling tank1 #cj ,broad irrigation1 #ih areas1 maintenance of1 #ajh methods of applying sewage in1 #ajd sewage disposal by1 area required1 #ajb when advisable1 #aaj ,clay soils for sewage purification1 #i ,cleaning settling tanks1 #cb ,composition of sewage1 #d ,concrete for walls and floors of settling tanks1 #bd walls1 forms for constructing1 #bb ,contact beds1 #hg alternating flow to1 #hi general features of construction of1 #hi principles involved1 #hh table for use in constructing1 #ib underdrainage of1 #hi ,cost items of sewage-disposal plant1 table on which to base estimates1 #abe ,cost of broken stone1 #abd of concrete1 #aai of dosing devices or siphons1 #abb of excavating and refilling1 #aae of finishing and cleaning up1 #abd of forms for concrete walls1 #aba of laying sewers and drains1 #aac of maintaining sewage-disposal plants1 #abg of material1 #aac for filter beds1 #abc of rock excavation1 #aag of sand1 #aad of sewage-disposal plants1 #aab of valves1 #abb ,crops1 yield of1 with and without sewage irrigation1 #ajc ,disease1 transmission of1 by insects1 #a ,dosing apparatus1 ,ansonia automatic1 #dc three kinds of1 #ec ,drain pipe from settling tank1 #bf ,emscher or ,imhoff tanks1 #cd ,excavation for settling tanks1 #be ,fertilizing elements in sewage1 value of1 #ih ,forms for building settling tanks1 #bb ,grease traps in connection with sand filters1 #gh ,imhoff or ,emscher tanks1 #cd ,irrigation1 amount of water necessary for1 #aja of orchards1 #ajh value of sewage for1 #ii ,laws against disposal of sewage into streams1 #c ,manholes through settling-tank roof1 #bi ,overflow pipe from siphon chamber1 #ca ,roof of settling tank1 construction of1 #bg ,sand filters1 alternating flow of effluent to different beds composing1 #hc artificially constructed1 #gi details of construction of1 #gd devices for dosing1 #hb distribution of effluent over1 #gh preparation for winter of1 #hd quality of sand suitable for1 #hf scraping surface of1 #hd settling of sewage before application to1 #gg table for use in constructing1 #gf underdrainage of1 #ha ,sand filtration1 #gd ,screening of sewage1 #e ,settling-tank floors1 necessary slope of1 #bf tanks compared with septic tanks1 #aa construction of floors of1 #be description of1 #af dimensions for1 #ah function of1 #ad location of1 #bj near sub-surface irrigation field1 #ca materials for and construction of1 #bj operation of1 #cb partial treatment only provided by1 #af water-tight1 construction of1 #bd ,sewage1 composition and character of1 #d disposal--an engineering problem1 #a ,sewage disposal3 by dilution1 #c in soils1 three essential conditions for1 #h need of1 #b plants1 permissible rates of operation of1 #h preliminary and final methods of1 #aa ,sewage filters1 #gc proper operation necessary to success of1 #if relative efficiency of various types of1 #gc ,sewer1 size and gradient of effluent1 #fc1 #gg ,siphon chamber1 depth of sewage in1 #ch ,siphon chambers1 #ba1 #fj necessity for1 #cg ,siphon1 ,miller1 #de simplest form of1 #dd ,van ,vranken1 #dd ,siphons1 alternating air-lock1 #eb discharging depth or draught of1 #gg for automatic discharge of sewage effluent1 #db how to place1 in position1 #be1 #fd1 #gg ,merritt1 #ej placing two in one chamber for alternating flow1 #dg plural alternating1 #dh sketches of and directions for setting furnished by manufacturers of1 #ec ,size of dose in disposal plants1 #aj ,sludge pipe from settling tank1 #bg ,soils and their suitability in purifying sewage1 #g ,sprinkling filters1 #ic construction and operation of1 #id ,sub-surface irrigation1 conditions favorable to1 #ga description of1 #ee fields1 location of1 #eh soils suitable for1 #eg special advantages of1 for country home1 #eg system--advantages over cesspools1 #ef systems1 alternate use of different portions of1 #fh details of construction of1 #eh1 #fc value of underdrainage in1 #fi tables for use in constructing1 #ei underdrains for1 #fi ,sub-surface tiling1 depth below ground surface of1 #fg gradient or fall of1 #fg how to lay1 #fd necessary length of1 #ff ,timed siphons for discharging contact beds1 #ia ,valves1 ,english slide1 #dj flap attached to sewer pipe1 #da with loose-link hinges1 #db with metallic seat1 #da hand1 #ci ordinary gate1 #dj sluice gate1 #dj ,,short-,,title ,,catalogue ,,of ,,the ,,publications ,,of ,,john ,,wiley ,,sons ,,new ,,york ,,london3 ,,chapman ,,hall1 ,,limited ,,arranged ,,under ,,subjects ,descriptive circulars sent on application4 ,books marked with an asterisk 7997 are sold at net prices only4 ,all books are bound in cloth unless otherwise stated4 ,,agriculture--,,horticulture--,,forestr y4 ,armsby's ,principles of ,animal ,nutrition #hvo1 #d #jj 99 ,bowman's ,forest ,physiography #hvo1 #e #jj ,budd and ,hansen's ,american ,horticultural ,manual3 ,part ,i4 ,propagation1 ,culture1 and ,improvement #abmo1 #a #ej ,part ,,ii4 ,systematic ,pomology #abmo1 #a #ej ,elliott's ,engineering for ,land ,drainage #abmo1 #b #jj ,practical ,farm ,drainage4 7,second ,edition1 #abmo1 #a #ej ,rewritten7 ,fuller's ,water ,supplies for the ,farm4 7,in ,press47 ,graves's ,forest ,mensuration #hvo1 #d #jj 99 ,principles of ,handling ,woodlands ,large #abmo1 #a #ej ,green's ,principles of ,american ,forestry #abmo1 #a #ej ,grotenfelt's ,principles of ,modern ,dairy ,practice4 #abmo1 #b #jj 7,woll47 ,hawley and ,hawes's ,practical ,forestry for ,new ,england4 7,in ,press47 99 ,herrick's ,denatured or ,industrial ,alcohol #hvo1 #d #jj 99 ,kemp and ,waugh's ,landscape ,gardening4 7,new ,edition1 #abmo1 #a #ej ,rewritten47 99 ,mc,kay and ,larsen's ,principles and ,practice of #hvo1 #a #ej ,butter-making ,maynard's ,landscape ,gardening as ,applied to ,home #abmo1 #a #ej ,decoration ,record's ,identification of the ,economic ,woods of the ,united ,states 7,in ,press47 ,sanderson's ,insects ,injurious to ,staple ,crops #abmo1 #a #ej 99 ,insect ,pests of ,farm1 ,garden1 and ,orchard #abmo1 #c #jj 99 ,schwarz's ,longleaf ,pine in ,virgin ,forest #abmo1 #a #be 99 ,solotaroff's ,field ,book for ,street-tree ,mapping #abmo1 #j #ge ,in lots of one dozen #h #jj 99 ,shade ,trees in ,towns and ,cities #hvo1 #c #jj ,stockbridge's ,rocks and ,soils #hvo1 #b #ej ,winton's ,microscopy of ,vegetable ,foods #hvo1 #g #ej ,woll's ,handbook for ,farmers and ,dairymen #afmo1 #a #ej ,,architecture4 99 ,atkinson's ,orientation of ,buildings or ,planning for #hvo1 #b #jj ,sunlight ,baldwin's ,steam ,heating for ,buildings #abmo1 #b #ej ,berg's ,buildings and ,structures of ,american ,railroads #dto1 #e #jj ,birkmire's ,architectural ,iron and ,steel #hvo1 #c #ej ,compound ,riveted ,girders as ,applied in ,buildings #hvo1 #b #jj ,planning and ,construction of ,high ,office #hvo1 #c #ej ,buildings ,skeleton ,construction in ,buildings #hvo1 #c #jj ,briggs's ,modern ,american ,school ,buildings #hvo1 #d #jj ,byrne's ,inspection of ,materials and ,workmanship #afmo1 #c #jj ,employed in ,construction4 ,carpenter's ,heating and ,ventilating of ,buildings #hvo1 #d #jj 99 ,corthell's ,allowable ,pressure on ,deep ,foundations #abmo1 #a #be 99 ,eckel's ,building ,stones and ,clays #hvo1 #c #jj ,freitag's ,architectural ,engineering #hvo1 #c #ej ,fire ,prevention and ,fire ,protection4 7,in ,press47 ,fireproofing of ,steel ,buildings #hvo1 #b #ej ,gerhard's ,guide to ,sanitary ,inspections4 7,fourth #abmo1 #a #ej ,edition1 ,entirely ,revised and ,enlarged47 99 ,modern ,baths and ,bath ,houses #hvo1 #c #jj ,sanitation of ,public ,buildings #abmo1 #a #ej ,theatre ,fires and ,panics #abmo1 #a #ej 99 ,the ,water ,supply1 ,sewerage and ,plumbing of #hvo1 #d #jj ,modern ,city ,buildings1 ,johnson's ,statics by ,algebraic and ,graphic ,methods #hvo1 #b #jj ,kellaway's ,how to ,lay ,out ,suburban ,home ,grounds #hvo1 #b #jj ,kidder's ,architects' and ,builders' ,pocket-book #afmo1 mor4 #e #jj ,merrill's ,stones for ,building and ,decoration #hvo1 #e #jj ,monckton's ,stair-building #dto1 #d #jj ,patton's ,practical ,treatise on ,foundations #hvo1 #e #jj ,peabody's ,naval ,architecture #hvo1 #g #ej ,rice's ,concrete-block ,manufacture #hvo1 #b #jj ,richey's ,handbook for ,superintendents of ,construction #afmo1 mor4 #d #jj ,building ,foreman's ,pocket ,book and ,ready #afmo1 mor4 #e #jj ,reference 99 ,building ,mechanics' ,ready ,reference ,series3 99 ,carpenters' and ,woodworkers' ,edition #afmo1 mor4 #a #ej 99 ,cement ,workers' and ,plasterers' ,edition #afmo1 mor4 #a #ej 99 ,plumbers'1 ,steam-,fitters'1 and ,tinners' #afmo1 mor4 #a #ej ,edition 99 ,stone-and ,brick-masons' ,edition #afmo1 mor4 #a #ej ,sabin's ,house ,painting #abmo1 #a #jj ,siebert and ,biggin's ,modern ,stone-cutting and ,masonry #hvo1 #a #ej ,snow's ,principal ,species of ,wood #hvo1 #c #ej ,wait's ,engineering and ,architectural ,jurisprudence #hvo1 #f #jj ,sheep1 #f #ej ,law of ,contracts #hvo1 #c #jj ,law of ,operations ,preliminary to ,construction in #hvo1 #e #jj ,engineering and ,architecture ,sheep1 #e #ej ,wilson's ,air ,conditioning #abmo1 #a #ej ,worcester and ,atkinson's ,small ,hospitals1 #abmo1 #a #be ,establishment and ,maintenance1 ,suggestions for ,hospital ,architecture1 with ,plans for a ,small ,hospital ,,army ,,and ,,navy4 ,bernadou's ,smokeless ,powder1 ,nitro-cellulose1 and the #abmo1 #b #ej ,theory of the ,cellulose ,molecule ,chase's ,art of ,pattern ,making #abmo1 #b #ej ,screw ,propellers and ,marine ,propulsion #hvo1 #c #jj 99 ,cloke's ,enlisted ,specialists' ,examiner #hvo1 #b #jj 99 ,gunner's ,examiner #hvo1 #a #ej ,craig's ,azimuth #dto1 #c #ej ,crehore and ,squier's ,polarizing ,photo-chronograph #hvo1 #c #jj 99 ,davis's ,elements of ,law #hvo1 #b #ej 99 ,treatise on the ,military ,law of ,united ,states #hvo1 #g #jj 99 ,dudley's ,military ,law and the ,procedure of ,large #abmo1 #b #ej ,courts-martial ,durand's ,resistance and ,propulsion of ,ships #hvo1 #e #jj 99 ,dyer's ,handbook of ,light ,artillery #abmo1 #c #jj ,eissler's ,modern ,high ,explosives #hvo1 #d #jj 99 ,fiebeger's ,text-book on ,field ,fortification ,large #abmo1 #b #jj ,hamilton and ,bond's ,the ,gunner's ,catechism #ahmo1 #a #jj 99 ,hoff's ,elementary ,naval ,tactics #hvo1 #a #fj ,ingalls's ,handbook of ,problems in ,direct ,fire #hvo1 #d #jj 99 ,interior ,ballistics #hvo1 #c #jj 99 ,lissak's ,ordnance and ,gunnery #hvo1 #f #jj 99 ,ludlow's ,logarithmic and ,trigonometric ,tables #hvo1 #a #jj 99 ,lyons's ,treatise on ,electromagnetic ,phenomena4 #hvo1 each1 #f #jj ,vols4 ,i4 and ,,ii4 99 ,mahan's ,permanent ,fortifications4 7,mercur47 #hvo1 half #g #ej mor4 ,manual for ,courts-martial #afmo1 mor4 #a #ej 99 ,mercur's ,attack of ,fortified ,places #abmo1 #b #jj 99 ,elements of the ,art of ,war #hvo1 #d #jj ,nixon's ,adjutants' ,manual #bdmo1 #a #jj ,peabody's ,naval ,architecture #hvo1 #g #ej 99 ,phelps's ,practical ,marine ,surveying #hvo1 #b #ej ,putnam's ,nautical ,charts #hvo1 #b #jj ,rust's ,ex-meridian ,altitude1 ,azimuth and ,star-,finding #hvo1 #e #jj ,tables 99 ,selkir's ,catechism of ,manual of ,guard ,duty #bdmo1 #j #ej ,sharpe's ,art of ,subsisting ,armies in ,war #ahmo1 mor4 #a #ej 99 ,taylor's ,speed and ,power of ,ships4 #b vols4 ,text #hvo1 #g #ej plates oblong #dto1 99 ,tupes and ,poole's ,manual of ,bayonet ,exercises and #bdmo1 #j #ej ,musketry ,fencing4 leather1 99 ,weaver's ,military ,explosives #hvo1 #c #jj 99 ,woodhull's ,military ,hygiene for ,officers of the ,large #abmo1 #a #ej ,line ,,assaying4 ,betts's ,lead ,refining by ,electrolysis #hvo1 #d #jj 99 ,butler's ,handbook of ,blowpipe ,analysis #afmo1 #j #ge ,fletcher's ,practical ,instructions in ,quantitative #afmo1 mor4 #a #ej ,assaying with the ,blowpipe ,furman and ,pardoe's ,manual of ,practical ,assaying #hvo1 #c #jj ,lodge's ,notes on ,assaying and ,metallurgical #hvo1 #c #jj ,laboratory ,experiments ,low's ,technical ,methods of ,ore ,analysis #hvo1 #c #jj ,miller's ,cyanide ,process #abmo1 #a #jj ,manual of ,assaying #abmo1 #a #jj ,minet's ,production of ,aluminum and its ,industrial #abmo1 #b #ej ,use4 7,waldo47 ,ricketts and ,miller's ,notes on ,assaying #hvo1 #c #jj ,robine and ,lenglen's ,cyanide ,industry4 7,le ,clerc47 #hvo1 #d #jj 99 ,seamon's ,manual for ,assayers and ,chemists ,large #abmo1 #b #ej ,ulke's ,modern ,electrolytic ,copper ,refining #hvo1 #c #jj ,wilson's ,chlorination ,process #abmo1 #a #ej ,cyanide ,processes #abmo1 #a #ej ,,astronomy4 ,comstock's ,field ,astronomy for ,engineers #hvo1 #b #ej ,craig's ,azimuth #dto1 #c #ej ,crandall's ,text-book on ,geodesy and ,least ,squares #hvo1 #c #jj ,doolittle's ,treatise on ,practical ,astronomy #hvo1 #d #jj ,hayford's ,text-book of ,geodetic ,astronomy #hvo1 #c #jj ,hosmer's ,azimuth #afmo1 mor4 #a #jj 99 ,text-book on ,practical ,astronomy #hvo1 #b #jj ,merriman's ,elements of ,precise ,surveying and ,geodesy #hvo1 #b #ej 99 ,michie and ,harlow's ,practical ,astronomy #hvo1 #c #jj ,rust's ,ex-meridian ,altitude1 ,azimuth and ,star-,finding #hvo1 #e #jj ,tables 99 ,white's ,elements of ,theoretical and ,descriptive #abmo1 #b #jj ,astronomy ,,chemistry4 99 ,abderhalden's ,physiological ,chemistry in ,thirty #hvo1 #e #jj ,lectures4 7,hall and ,defren47 99 ,abegg's ,theory of ,electrolytic ,dissociation1 7von #abmo1 #a #be ,ende47 ,alexeyeff's ,general ,principles of ,organic ,syntheses4 #hvo1 #c #jj 7,matthews47 ,allen's ,tables for ,iron ,analysis #hvo1 #c #jj ,armsby's ,principles of ,animal ,nutrition #hvo1 #d #jj ,arnold's ,compendium of ,chemistry4 7,mandel47 ,large #abmo1 #c #ej ,association of ,state and ,national ,food and ,dairy #hvo1 #c #jj ,departments1 ,hartford ,meeting1 #aijf ,jamestown ,meeting1 #aijg #hvo1 #c #jj ,austen's ,notes for ,chemical ,students #abmo1 #a #ej ,bernadou's ,smokeless ,powder4--,nitro-cellulose1 and #abmo1 #b #ej ,theory of the ,cellulose ,molecule 99 ,biltz's ,introduction to ,inorganic ,chemistry4 7,hall #abmo1 #a #be and ,phelan47 ,laboratory ,methods of ,inorganic ,chemistry4 7,hall #hvo1 #c #jj and ,blanchard47 99 ,bingham and ,white's ,laboratory ,manual of ,inorganic #abmo1 #a #jj ,chemistry 99 ,blanchard's ,synthetic ,inorganic ,chemistry #abmo1 #a #jj 99 ,bottler's ,german and ,american ,varnish ,making4 ,large #abmo1 #c #ej 7,sabin47 ,browne's ,handbook of ,sugar ,analysis4 7,in ,press47 99 ,browning's ,introduction to the ,rarer ,elements #hvo1 #a #ej 99 ,butler's ,handbook of ,blowpipe ,analysis #afmo1 #j #ge 99 ,claassen's ,beet-sugar ,manufacture4 7,hall and #hvo1 #c #jj ,rolfe47 ,classen's ,quantitative ,chemical ,analysis by #hvo1 #c #jj ,electrolysis4 7,boltwood47 ,cohn's ,indicators and ,test-papers #abmo1 #b #jj ,tests and ,reagents #hvo1 #c #jj ,cohnheim's ,functions of ,enzymes and ,ferments4 7,in ,press47 99 ,danneel's ,electrochemistry4 7,merriam47 #abmo1 #a #be ,dannerth's ,methods of ,textile ,chemistry #abmo1 #b #jj ,duhem's ,thermodynamics and ,chemistry4 7,burgess47 #hvo1 #d #jj ,effront's ,enzymes and their ,applications4 #hvo1 #c #jj 7,prescott47 ,eissler's ,modern ,high ,explosives #hvo1 #d #jj 99 ,fischer's ,oedema #hvo1 #b #jj 99 ,physiology of ,alimentation ,large #abmo1 #b #jj ,fletcher's ,practical ,instructions in ,quantitative #afmo1 mor4 #a #ej ,assaying with the ,blowpipe ,fowler's ,sewage ,works ,analyses #abmo1 #b #jj ,fresenius's ,manual of ,qualitative ,chemical ,analysis4 #hvo1 #e #jj 7,wells47 ,manual of ,qualitative ,chemical ,analysis4 ,part ,i4 #hvo1 #c #jj ,descriptive4 7,wells47 ,quantitative ,chemical ,analysis4 7,cohn47 #b vols4 #hvo1 #ab #ej ,when ,sold ,separately1 ,vol4 ,i1 #f4 ,vol4 ,,ii1 #h4 ,fuertes's ,water and ,public ,health #abmo1 #a #ej ,furman and ,pardoe's ,manual of ,practical ,assaying #hvo1 #c #jj 99 ,getman's ,exercises in ,physical ,chemistry #abmo1 #b #jj ,gill's ,gas and ,fuel ,analysis for ,engineers #abmo1 #a #be ,gooch's ,summary of ,methods in ,chemical ,analysis4 7,in ,press47 99 ,gooch and ,browning's ,outlines of ,qualitative ,large #abmo1 #a #be ,chemical ,analysis ,grotenfelt's ,principles of ,modern ,dairy ,practice4 #abmo1 #b #jj 7,woll47 ,groth's ,introduction to ,chemical ,crystallography #abmo1 #a #be 7,marshall47 99 ,hammarsten's ,text-book of ,physiological ,chemistry4 #hvo1 #d #jj 7,mandel47 ,hanausek's ,microscopy of ,technical ,products4 #hvo1 #e #jj 7,winton47 99 ,haskins and ,macleod's ,organic ,chemistry #abmo1 #b #jj 99 ,herrick's ,denatured or ,industrial ,alcohol #hvo1 #d #jj ,hinds's ,inorganic ,chemistry #hvo1 #c #jj 99 ,laboratory ,manual for ,students #abmo1 #a #jj 99 ,holleman's ,laboratory ,manual of ,organic ,chemistry #abmo1 #a #jj for ,beginners4 7,walker47 ,text-book of ,inorganic ,chemistry4 7,cooper47 #hvo1 #b #ej ,text-book of ,organic ,chemistry4 7,walker and #hvo1 #b #ej ,mott47 ,holley's ,analysis of ,paint and ,varnish ,products4 7,in ,press47 99 ,lead and ,zinc ,pigments ,large #abmo1 #c #jj ,hopkins's ,oil-chemists' ,handbook #hvo1 #c #jj ,jackson's ,directions for ,laboratory ,work in #hvo1 #a #be ,physiological ,chemistry ,johnson's ,rapid ,methods for the ,chemical ,analysis of ,large #abmo1 #c #jj ,special ,steels1 ,steelmaking ,alloys and ,graphite ,landauer's ,spectrum ,analysis4 7,tingle47 #hvo1 #c #jj ,lassar-,cohn's ,application of ,some ,general ,reactions #abmo1 #a #jj to ,investigations in ,organic ,chemistry4 7,tingle47 ,leach's ,inspection and ,analysis of ,food with ,special #hvo1 #g #ej ,reference to ,state ,control ,lob's ,electrochemistry of ,organic ,compounds4 #hvo1 #c #jj 7,lorenz47 ,lodge's ,notes on ,assaying and ,metallurgical #hvo1 #c #jj ,laboratory ,experiments ,low's ,technical ,method of ,ore ,analysis #hvo1 #c #jj ,lowe's ,paint for ,steel ,structures #abmo1 #a #jj ,lunge's ,techno-chemical ,analysis4 7,cohn47 #abmo1 #a #jj 99 ,mc,kay and ,larsen's ,principles and ,practice of #hvo1 #a #fj ,butter-making ,maire's ,modern ,pigments and their ,vehicles #abmo1 #b #jj ,mandel's ,handbook for ,bio-chemical ,laboratory #abmo1 #a #fj 99 ,martin's ,laboratory ,guide to ,qualitative ,analysis #abmo1 #j #fj with the ,blowpipe ,mason's ,examination of ,water4 7,chemical and #abmo1 #a #be ,bacteriological47 ,water-supply4 7,considered ,principally from a #hvo1 #d #jj ,sanitary ,standpoint47 99 ,mathewson's ,first ,principles of ,chemical ,theory #hvo1 #a #jj ,matthews's ,laboratory ,manual of ,dyeing and ,textile #hvo1 #c #ej ,chemistry ,textile ,fibres4 #b;d ,edition1 ,rewritten #hvo1 #d #jj 99 ,meyer's ,determination of ,radicles in ,carbon #abmo1 #a #be ,compounds4 7,tingle47 ,third ,edition ,miller's ,cyanide ,process #abmo1 #a #jj ,manual of ,assaying #abmo1 #a #jj ,minet's ,production of ,aluminum and its ,industrial #abmo1 #b #ej ,use4 7,waldo47 99 ,mittelstaedt's ,technical ,calculations for ,sugar #abmo1 #a #ej ,works4 7,bourbakis47 ,mixter's ,elementary ,text-book of ,chemistry #abmo1 #a #ej ,morgan's ,elements of ,physical ,chemistry #abmo1 #c #jj 99 ,physical ,chemistry for ,electrical ,engineers #abmo1 #a #ej 99 ,moore's ,experiments in ,organic ,chemistry #abmo1 #j #ej 99 ,outlines of ,organic ,chemistry #abmo1 #a #ej ,morse's ,calculations used in ,cane-sugar ,factories #afmo1 mor4 #a #ej 99 ,muir's ,history of ,chemical ,theories and ,laws #hvo1 #d #jj ,mulliken's ,general ,method for the ,identification of ,pure ,organic ,compounds ,vol4 ,i4 ,compounds of ,carbon with ,hydrogen and ,large #hvo1 #e #jj ,oxygen ,vol4 ,,ii4 ,nitrogenous ,compounds4 7,in ,preparation47 ,vol4 ,,iii4 ,the ,commercial ,dyestuffs ,large #hvo1 #e #jj 99 ,nelson's ,analysis of ,drugs and ,medicines #abmo1 #e #jj ,ostwald's ,conversations on ,chemistry4 ,part ,one4 #abmo1 #a #ej 7,ramsey47 ,ostwald's ,conversations on ,chemistry4 ,part ,two4 #abmo1 #b #jj 7,turnbull47 99 ,introduction to ,chemistry4 7,hall and ,large #abmo1 #a #ej ,williams47 ,owen and ,standage's ,dyeing and ,cleaning of ,textile #abmo1 #b #jj ,fabrics 99 ,palmer's ,practical ,test ,book of ,chemistry #abmo1 #a #jj 99 ,pauli's ,physical ,chemistry in the ,service of #abmo1 #a #be ,medicine4 7,fischer47 ,penfield's ,tables of ,minerals1 ,including the ,use of #hvo1 #a #jj ,minerals and ,statistics of ,domestic ,production ,pictet's ,alkaloids and their ,chemical ,constitution4 #hvo1 #e #jj 7,biddle47 ,poole's ,calorific ,power of ,fuels #hvo1 #c #jj ,prescott and ,winslow's ,elements of ,water #abmo1 #a #ej ,bacteriology1 with ,special ,reference to ,sanitary ,water ,analysis 99 ,reisig's ,guide to ,piece-,dyeing #hvo1 #be #jj ,richards and ,woodman's ,air1 ,water1 and ,food from a #hvo1 #b #jj ,sanitary ,standpoint ,ricketts and ,miller's ,notes on ,assaying #hvo1 #c #jj ,rideal's ,disinfection and the ,preservation of ,food #hvo1 #d #jj ,riggs's ,elementary ,manual for the ,chemical ,laboratory #hvo1 #a #be ,robine and ,lenglen's ,cyanide ,industry4 7,le ,clerc47 #hvo1 #d #jj ,ruddiman's ,incompatibilities in ,prescriptions #hvo1 #b #jj ,whys in ,pharmacy #abmo1 #a #jj 99 ,ruer's ,elements of ,metallography4 7,mathewson47 #hvo1 #c #jj ,sabin's ,industrial and ,artistic ,technology of ,paint #hvo1 #c #jj and ,varnish ,salkowski's ,physiological and ,pathological ,chemistry4 #hvo1 #b #ej 7,orndorff47 99 ,schimpf's ,essentials of ,volumetric ,analysis ,large #abmo1 #a #ej ,manual of ,volumetric ,analysis4 7,fifth ,edition1 #hvo1 #e #jj ,rewritten7 99 ,qualitative ,chemical ,analysis #hvo1 #a #be 99 ,seamon's ,manual for ,assayers and ,chemists ,large #abmo1 #b #ej ,smith's ,lecture ,notes on ,chemistry for ,dental #hvo1 #b #ej ,students ,spencer's ,handbook for ,cane ,sugar ,manufacturers #afmo1 mor4 #c #jj ,handbook for ,chemists of ,beet-sugar ,houses #afmo1 mor4 #c #jj ,stockbridge's ,rocks and ,soils #hvo1 #b #ej ,stone's ,practical ,testing of ,gas and ,gas ,meters #hvo1 #c #ej 99 ,tillman's ,descriptive ,general ,chemistry #hvo1 #c #jj 99 ,elementary ,lessons in ,heat #hvo1 #a #ej ,treadwell's ,qualitative ,analysis4 7,hall47 #hvo1 #c #jj ,quantitative ,analysis1 7,hall47 #hvo1 #d #jj ,turneaure and ,russell's ,public ,water-supples #hvo1 #e #jj ,van ,deventer's ,physical ,chemistry for ,beginners4 #abmo1 #a #ej 7,boltwood47 ,venable's ,methods and ,devices for ,bacterial ,treatment #hvo1 #c #jj of ,sewage ,ward and ,whipple's ,freshwater ,biology4 7,in ,press47 ,ware's ,beet-sugar ,manufacture and ,refining4 ,vol4 ,i4 #hvo1 #d #jj ,ware's ,beet-sugar ,manufacture and ,refining4 ,vol4 ,,ii4 #hvo1 #e #jj ,washington's ,manual of the ,chemical ,analysis of ,rocks #hvo1 #b #jj 99 ,weaver's ,military ,explosives #hvo1 #c #jj ,wells's ,laboratory ,guide in ,qualitative ,chemical #hvo1 #a #ej ,analysis ,short ,course in ,inorganic ,qualitative ,chemical #abmo1 #a #ej ,analysis for ,engineering ,students ,text-book of ,chemical ,arithmetic #abmo1 #a #be ,whipple's ,microscopy of ,drinking-water #hvo1 #c #ej ,wilson's ,chlorination ,process #abmo1 #a #ej ,cyanide ,processes #abmo1 #a #ej ,winton's ,microscopy of ,vegetable ,foods #hvo1 #g #ej ,zsigmondy's ,colloids and the ,ultramicroscope4 ,large #abmo1 #c #jj 7,alexander47 ,,civil ,,engineering4 ,,bridges ,,and ,,roofs4 ,,hydraulics4 ,,materials ,,of ,,engineering4 ,,railway ,,engineering4 99 ,american ,civil ,engineers' ,pocket ,book4 7,mansfield #afmo1 mor4 #e #jj ,merriman1 ,editor-in-chief47 ,baker's ,engineers' ,surveying ,instruments #abmo1 #c #jj ,bixby's ,graphical ,computing ,table ,paper #ai #j #be #bd inches4 ,breed and ,hosmer's ,principles and ,practice of #hvo1 #c #jj ,surveying4 ,vol4 ,i4 ,elementary ,surveying ,vol4 ,,ii4 ,higher ,surveying #hvo1 #b #ej 99 ,burr's ,ancient and ,modern ,engineering and the #hvo1 #c #ej ,isthmian ,canal ,comstock's ,field ,astronomy for ,engineers #hvo1 #b #ej 99 ,corthell's ,allowable ,pressure on ,deep ,foundations #abmo1 #a #be ,crandall's ,text-book on ,geodesy and ,least ,squares #hvo1 #c #jj ,davis's ,elevation and ,stadia ,tables #hvo1 #a #jj 99 ,eckel's ,building ,stones and ,clays #hvo1 #c #jj ,elliott's ,engineering for ,land ,drainage #abmo1 #b #jj 99 ,fiebeger's ,treatise on ,civil ,engineering #hvo1 #e #jj ,flemer's ,phototopographic ,methods and ,instruments #hvo1 #e #jj ,folwell's ,sewerage4 7,designing and ,maintenance47 #hvo1 #c #jj ,freitag's ,architectural ,engineering #hvo1 #c #ej ,french and ,ives's ,stereotomy #hvo1 #b #ej ,gilbert1 ,wightman1 and ,saunders's ,subways and ,tunnels of ,new ,york4 7,in ,press47 99 ,hauch and ,rice's ,tables of ,quantities for #abmo1 #a #be ,preliminary ,estimates ,hayford's ,text-book of ,geodetic ,astronomy #hvo1 #c #jj ,hering's ,ready ,reference ,tables 7,conversion ,factors47 #afmo1 mor4 #b #ej ,hosmer's ,azimuth #afmo1 mor4 #a #jj 99 ,text-book on ,practical ,astronomy #hvo1 #b #jj ,howe's ,retaining ,walls for ,earth #abmo1 #a #be 99 ,ives's ,adjustments of the ,engineer's ,transit and #afmo1 bds4 #j #be ,level ,ives and ,hilts's ,problems in ,surveying1 ,railroad #afmo1 mor4 #a #ej ,surveying and ,geodesy 99 ,johnson 7,j4,b47 and ,smith's ,theory and ,practice of ,large #abmo1 #c #ej ,surveying ,johnson's 7,l4 ,j47 ,statics by ,algebraic and ,graphic #hvo1 #b #jj ,methods 99 ,kinnicutt1 ,winslow and ,pratt's ,sewage ,disposal #hvo1 #c #jj 99 ,mahan's ,descriptive ,geometry #hvo1 #a #ej ,merriman's ,elements of ,precise ,surveying and ,geodesy #hvo1 #b #ej ,merriman and ,brooks's ,handbook for ,surveyors #afmo1 mor4 #b #jj ,nugent's ,plane ,surveying #hvo1 #c #ej ,ogden's ,sewer ,construction #hvo1 #c #jj ,sewer ,design #abmo1 #b #jj ,ogden and ,cleveland's ,practical ,methods of ,sewage ,disposal for ,residences1 ,hotels1 and ,institutions47,in ,press47 ,parsons's ,disposal of ,municipal ,refuse #hvo1 #b #jj ,patton's ,treatise on ,civil ,engineering #hvo1 half #g #ej leather1 ,reed's ,topographical ,drawing and ,sketching #dto1 #e #jj ,riemer's ,shaft-sinking under ,difficult ,conditions4 #hvo1 #c #jj 7,corning and ,peele47 ,siebert and ,biggin's ,modern ,stone-cutting and ,masonry #hvo1 #a #ej ,smith's ,manual of ,topographical ,drawing4 7,mc,millan47 #hvo1 #b #ej ,soper's ,air and ,ventilation of ,subways #abmo1 #b #ej 99 ,tracy's ,exercises in ,surveying #abmo1 mor4 #a #jj ,tracy's ,plane ,surveying #afmo1 mor4 #c #jj ,venable's ,garbage ,crematories in ,america #hvo1 #b #jj ,methods and ,devices for ,bacterial ,treatment of #hvo1 #c #jj ,sewage ,wait's ,engineering and ,architectural ,jurisprudence #hvo1 #f #jj ,sheep1 #f #ej ,law of ,contracts #hvo1 #c #jj ,law of ,operations ,preliminary to ,construction in #hvo1 #e #jj ,engineering and ,architecture ,sheep1 #e #ej ,warren's ,stereotomy--,problems in ,stone-cutting #hvo1 #b #ej 99 ,waterbury's ,vest-,pocket ,hand-book of ,mathematics #b #e #a #jj for ,engineers4 inches1 mor4 99 ,enlarged ,edition1 ,including ,tables mor4 #a #ej ,webb's ,problems in the ,use and ,adjustment of #afmo1 mor4 #a #be ,engineering ,instruments4 ,wilson's ,topographic ,surveying #hvo1 #c #ej ,,bridges ,,and ,,roofs4 ,boller's ,practical ,treatise on the ,construction of #hvo1 #b #jj ,iron ,highway ,bridges4 99 ,thames ,river ,bridge ,oblong #e #jj paper1 ,burr and ,falk's ,design and ,construction of ,metallic #hvo1 #e #jj ,bridges ,influence ,lines for ,bridge and ,roof ,computations #hvo1 #c #jj ,du ,bois's ,mechanics of ,engineering4 ,vol4 ,,ii ,small #dto1 #aj #jj ,foster's ,treatise on ,wooden ,trestle ,bridges #dto1 #e #jj ,fowler's ,ordinary ,foundations #hvo1 #c #ej ,greene's ,arches in ,wood1 ,iron1 and ,stone #hvo1 #b #ej ,bridge ,trusses #hvo1 #b #ej ,roof ,trusses #hvo1 #a #be ,grimm's ,secondary ,stresses in ,bridge ,trusses #hvo1 #b #ej ,heller's ,stresses in ,structures and the ,accompanying #hvo1 #c #jj ,deformations ,howe's ,design of ,simple ,roof-trusses in ,wood and #hvo1 #b #jj ,steel ,symmetrical ,masonry ,arches #hvo1 #b #ej ,treatise on ,arches #hvo1 #d #jj 99 ,hudson's ,deflections and ,statically ,indeterminate ,small #dto1 #c #ej ,stresses 99 ,plate ,girder ,design #hvo1 #a #ej 99 ,jacoby's ,structural ,details1 or ,elements of ,design #hvo1 #b #be in ,heavy ,framing ,johnson1 ,bryan and ,turneaure's ,theory and ,practice in ,small #dto1 #aj #jj the ,designing of ,modern ,framed ,structures 99 ,johnson1 ,bryan and ,turneaure's ,theory and ,practice #hvo1 #c #jj in the ,designing of ,modern ,framed ,structures4 ,new ,edition4 ,part ,i4 99 ,part ,,ii4 ,new ,edition #hvo1 #d #jj ,merriman and ,jacoby's ,text-book on ,roofs and ,bridges3 ,part ,i4 ,stresses in ,simple ,trusses #hvo1 #b #ej ,part ,,ii4 ,graphic ,statics #hvo1 #b #ej ,part ,,iii4 ,bridge ,design #hvo1 #b #ej ,part ,,iv4 ,higher ,structures #hvo1 #b #ej ,ricker's ,design and ,construction of ,roofs4 7,in ,press47 ,sondericker's ,graphic ,statics1 with ,applications to #hvo1 #b #jj ,trusses1 ,beams1 and ,arches ,waddell's ,de ,pontibus1 ,pocket-book for ,bridge #afmo1 mor4 #b #jj ,engineers 99 ,specifications for ,steel ,bridges #abmo1 #ej ,waddell and ,harrington's ,bridge ,engineering4 7,in ,preparation47 ,,hydraulics4 ,barnes's ,ice ,formation #hvo1 #c #jj ,bazin's ,experiments upon the ,contraction of the #hvo1 #b #jj ,liquid ,vein ,issuing from an ,orifice4 7,trautwine47 ,bovey's ,treatise on ,hydraulics #hvo1 #e #jj ,church's ,diagrams of ,mean ,velocity of ,water in ,open ,oblong #dto1 #a #ej ,channels4 paper1 ,hydraulic ,motors #hvo1 #b #jj ,mechanics of ,fluids 7,being ,part ,,iv of ,mechanics #hvo1 #c #jj of ,engineering7 ,coffin's ,graphical ,solution of ,hydraulic ,problems #afmo1 mor4 #b #ej ,flather's ,dynamometers1 and the ,measurement of ,power #abmo1 #c #jj ,folwell's ,water-supply ,engineering #hvo1 #d #jj ,frizell's ,water-power #hvo1 #e #jj ,fuertes's ,water and ,public ,health #abmo1 #a #ej ,water-filtration ,works #abmo1 #b #ej ,ganguillet and ,kutter's ,general ,formula for the #hvo1 #d #jj ,uniform ,flow of ,water in ,rivers and ,other ,channels4 7,hering and ,trautwine47 ,hazen's ,clean ,water and ,how to ,get ,it ,large #abmo1 #a #ej ,filtration of ,public ,water-supplies #hvo1 #c #jj ,hazelhurst's ,towers and ,tanks for ,water-works #hvo1 #b #ej ,herschel's #aae ,experiments on the ,carrying ,capacity #hvo1 #b #jj of ,large1 ,riveted1 ,metal ,conduits ,hoyt and ,grover's ,river ,discharge #hvo1 #b #jj ,hubbard and ,kiersted's ,water-works ,management and #hvo1 #d #jj ,maintenance 99 ,lyndon's ,development and ,electrical ,distribution of #hvo1 #c #jj ,water ,power ,mason's ,water-supply4 7,considered ,principally from a #hvo1 #d #jj ,sanitary ,standpoint47 99 ,merriman's ,treatise on ,hydraulics4 #ith ,edition1 #hvo1 #d #jj ,rewritten 99 ,molitor's ,hydraulics of ,rivers1 ,weirs and ,sluices #hvo1 #b #jj 99 ,morrison and ,brodie's ,high ,masonry ,dam ,design #hvo1 #a #ej 99 ,richards's ,laboratory ,notes on ,industrial ,water #hvo1 #ej ,analysis ,schuyler's ,reservoirs for ,irrigation1 ,water-power1 ,large #hvo1 #f #jj and ,domestic ,water-supply4 ,second ,edition1 ,revised and ,enlarged 99 ,thomas and ,watt's ,improvement of ,rivers #dto1 #f #jj ,turneaure and ,russell's ,public ,water-supplies #hvo1 #e #jj 99 ,wegmann's ,design and ,construction of ,dams #fth ,ed41 #dto1 #f #jj enlarged ,water-,supply of the ,city of ,new ,york from #afeh #dto1 #aj #jj to #ahie ,whipple's ,value of ,pure ,water ,large #abmo1 #a #jj ,williams and ,hazen's ,hydraulic ,tables #hvo1 #a #ej ,wilson's ,irrigation ,engineering #hvo1 #d #jj ,wood's ,turbines #hvo1 #b #ej ,,materials ,,of ,,engineering4 ,baker's ,roads and ,pavements #hvo1 #e #jj ,treatise on ,masonry ,construction #hvo1 #e #jj ,black's ,united ,states ,public ,works ,oblong #dto1 #e #jj 99 ,blanchard and ,drowne's ,highway ,engineering1 as #hvo1 #b #jj ,presented at the ,second ,international ,road ,congress1 ,brussels1 #aiaj ,bleininger's ,manufacture of ,hydraulic ,cement4 7,in ,preparation47 99 ,bottler's ,german and ,american ,varnish ,making4 ,large #abmo1 #c #ej 7,sabin47 ,burr's ,elasticity and ,resistance of the ,materials of #hvo1 #g #ej ,engineering ,byrne's ,highway ,construction #hvo1 #e #jj ,inspection of the ,materials and ,workmanship #afmo1 #c #jj ,employed in ,construction ,church's ,mechanics of ,engineering #hvo1 #f #jj ,mechanics of ,solids 7,being ,parts ,i1 ,,ii1 ,,iii of #hvo1 #d #ej ,mechanics of ,engineering7 ,du ,bois's ,mechanics of ,engineering ,vol4 ,i4 ,kinematics1 ,statics1 ,kinetics ,small #dto1 #g #ej ,vol4 ,,ii4 ,the ,stresses in ,framed ,structures1 ,small #dto1 #aj #jj ,strength of ,materials and ,theory of ,flexures 99 ,eckel's ,building ,stones and ,clays #hvo1 #c #jj 99 ,cements1 ,limes1 and ,plasters #hvo1 #f #jj ,fowler's ,ordinary ,foundations #hvo1 #c #ej 99 ,greene's ,structural ,mechanics #hvo1 #b #ej ,holley's ,analysis of ,paint and ,varnish ,products4 7,in ,press47 99 ,lead and ,zinc ,pigments ,large #abmo1 #c #jj 99 ,hubbard's ,dust ,preventives and ,road ,binders #hvo1 #c #jj ,johnson's 7,c4 ,m47 ,rapid ,methods for the ,chemical ,large #abmo1 #c #jj ,analysis of ,special ,steels1 ,steel-making ,alloys and ,graphite ,johnson's 7,j4 ,b47 ,materials of ,construction ,large #hvo1 #f #jj ,keep's ,cast ,iron #hvo1 #b #ej ,lanza's ,applied ,mechanics #hvo1 #g #ej ,lowe's ,paints for ,steel ,structures #abmo1 #a #jj ,maire's ,modern ,pigments and their ,vehicle #abmo1 #b #jj 99 ,martin's ,text ,book on ,mechanics4 ,vol4 ,i4 ,statics #abmo1 #a #be 99 ,vol4 ,,ii4 ,kinematics and ,kinetics #abmo1 #a #ej 99 ,vol4 ,,iii4 ,mechanics of ,materials #abmo1 #a #ej ,maurer's ,technical ,mechanics #hvo1 #d #jj ,merrill's ,stones for ,building and ,decoration #hvo1 #e #jj ,merriman's ,mechanics of ,materials #hvo1 #e #jj 99 ,strength of ,materials #abmo1 #a #jj ,metcalf's ,steel4 ,a ,manual for ,steel-users #abmo1 #b #jj ,morrison's ,highway ,engineering #hvo1 #b #ej 99 ,murdock's ,strength of ,materials #abmo1 #b #jj ,patton's ,practical ,treatise on ,foundations #hvo1 #e #jj ,rice's ,concrete ,block ,manufacture #hvo1 #b #jj ,richardson's ,modern ,asphalt ,pavement #hvo1 #c #jj ,richey's ,building ,foreman's ,pocket ,book and ,ready #afmo1 mor4 #e #jj ,reference 99 ,cement ,workers' and ,plasterers' ,edition #afmo1 mor4 #a #ej 7,building ,mechanics' ,ready ,reference ,series7 ,handbook for ,superintendents of ,construction #afmo1 mor4 #d #jj 99 ,stone and ,brick ,masons' ,edition 7,building #afmo1 mor4 #a #ej ,mechanics' ,ready ,reference ,series7 99 ,ries's ,clays3 ,their ,occurrence1 ,properties1 and #hvo1 #e #jj ,uses 99 ,ries and ,leighton's ,history of the ,clay-working #hvo4 #b #ej ,industry of the ,united ,states ,sabin's ,industrial and ,artistic ,technology of ,paint #hvo1 #c #jj and ,varnish 99 ,smith's ,strength of ,material #abmo1 #a #be ,snow's ,principal ,species of ,wood #hvo1 #c #ej ,spalding's ,hydraulic ,cement #abmo1 #b #jj ,text-book on ,roads and ,pavements #abmo1 #b #jj 99 ,taylor and ,thompson's ,concrete ,costs ,small #hvo1 #e #jj 99 ,extracts on ,reinforced ,concrete ,design #hvo1 #b #jj ,treatise on ,concrete1 ,plain and ,reinforced #hvo1 #e #jj ,thurston's ,materials of ,engineering4 ,in ,three ,parts #hvo1 #h #jj ,part ,i4 ,non-metallic ,materials of ,engineering #hvo1 #b #jj and ,metallurgy ,part ,,ii4 ,iron and ,steel #hvo1 #c #ej ,part ,,iii4 ,a ,treatise on ,brasses1 ,bronzes1 and #hvo1 #b #ej ,other ,alloys and their ,constituents ,tillson's ,street ,pavements and ,paving ,materials #hvo1 #d #jj ,turneaure and ,maurer's ,principles of ,reinforced #hvo1 #c #ej ,concrete ,construction4 ,second ,edition1 ,revised and ,enlarged ,waterbury's ,cement ,laboratory ,manual #abmo1 #a #jj 99 ,laboratory ,manual for ,testing ,materials of #abmo1 #a #ej ,construction ,wood's 7,de ,v47 ,treatise on the ,resistance of #hvo1 #b #jj ,materials1 and an ,appendix on the ,preservation of ,timber ,wood's 7,m4 ,p47 ,rustless ,coatings3 ,corrosion and #hvo1 #d #jj ,electrolysis of ,iron and ,steel ,,railway ,,engineering4 ,andrews's ,handbook for ,street ,railway ,engineers #c #e #a #be inches1 mor4 ,berg's ,buildings and ,structures of ,american ,railroads #dto1 #e #jj ,brooks's ,handbook of ,street ,railroad ,location #afmo1 mor4 #a #ej 99 ,burt's ,railway ,station ,service #abmo1 #b #jj ,butts's ,civil ,engineer's ,field-book #afmo1 mor4 #b #ej ,crandall's ,railway and ,other ,earthwork ,tables #hvo1 #a #ej ,crandall and ,barnes's ,railroad ,surveying #afmo1 mor4 #b #jj 99 ,crockett's ,methods for ,earthwork ,computations #hvo1 #a #ej ,dredge's ,history of the ,pennsylvania ,railroad4 7#ahgi7 ,paper4 #e #jj ,fisher's ,table of ,cubic ,yards ,cardboard1 #be ,godwin's ,railroad ,engineers' ,field-book and #afmo1 mor4 #b #ej ,explorers' ,guide ,hudson's ,tables for ,calculating the ,cubic ,contents of #hvo1 #a #jj ,excavations and ,embankments ,ives and ,hilts's ,problems in ,surveying1 ,railroad #afmo1 mor4 #a #ej ,surveying and ,geodesy ,molitor and ,beard's ,manual for ,resident ,engineers #afmo1 #a #jj ,nagle's ,field ,manual for ,railroad ,engineers #afmo1 mor4 #c #jj 99 ,orrock's ,railroad ,structures and ,estimates #hvo1 #c #jj ,philbrick's ,field ,manual for ,engineers #afmo1 mor4 #c #jj ,raymond's ,railroad ,field ,geometry #afmo1 mor4 #b #jj ,elements of ,railroad ,engineering #hvo1 #c #ej ,railroad ,engineer's ,field ,book4 7,in ,preparation47 ,roberts' ,track ,formul and ,tables #afmo4 mor4 #c #jj ,searles's ,field ,engineering #afmo1 mor4 #c #jj ,railroad ,spiral #afmo1 mor4 #a #ej ,taylor's ,prismoidal ,formul and ,earthwork #hvo1 #a #ej ,webb's ,economics of ,railroad ,construction ,large #abmo1 #b #ej ,railroad ,construction #afmo1 mor4 #e #jj ,wellington's ,economic ,theory of the ,location of ,large #abmo1 #e #jj ,railways ,wilson's ,elements of ,railroad-,track and ,construction #abmo1 #b #jj ,,drawing ,barr and ,wood's ,kinematics of ,machinery #hvo1 #b #ej 99 ,bartlett's ,mechanical ,drawing #hvo1 #c #jj 99 ,bartlett's ,mechanical ,drawing ,abridged ,ed4 #hvo1 #a #ej 99 ,bartlett and ,johnson's ,engineering ,descriptive #hvo1 #a #ej ,geometry ,blessing and ,darling's ,descriptive ,geometry4 7,in ,press47 ,elements of ,drawing4 7,in ,press47 ,coolidge's ,manual of ,drawing #hvo1 paper1 #a #jj ,coolidge and ,freeman's ,elements of ,general ,drafting ,oblong #dto1 #b #ej for ,mechanical ,engineers ,durley's ,kinematics of ,machines #hvo1 #d #jj ,emch's ,introduction to ,projective ,geometry and its #hvo1 #b #ej ,application ,hill's ,text-book on ,shades and ,shadows1 and #hvo1 #b #jj ,perspective ,jamison's ,advanced ,mechanical ,drawing #hvo1 #b #jj ,elements of ,mechanical ,drawing #hvo1 #b #ej ,jones's ,machine ,design3 ,part ,i4 ,kinematics of ,machinery #hvo1 #a #ej ,part ,,ii4 ,form1 ,strength1 and ,proportions of #hvo1 #c #jj ,parts 99 ,kimball and ,barr's ,machine ,design #hvo1 #c #jj ,mac,cord's ,elements of ,descriptive ,geometry #hvo1 #c #jj ,kinematics2 or1 ,practical ,mechanism #hvo1 #e #jj ,mechanical ,drawing #dto1 #d #jj ,velocity ,diagrams #hvo1 #a #ej ,mc,leod's ,descriptive ,geometry ,large #abmo1 #a #ej 99 ,mahan's ,descriptive ,geometry and ,stone-cutting #hvo1 #a #ej ,industrial ,drawing4 7,thompson47 #hvo1 #c #ej ,moyer's ,descriptive ,geometry #hvo1 #b #jj ,reed's ,topographical ,drawing and ,sketching #dto1 #e #jj 99 ,reid's ,mechanical ,drawing4 7,elementary and #hvo1 #b #jj ,advanced47 ,text-book of ,mechanical ,drawing and ,elementary #hvo1 #c #jj ,machine ,design ,robinson's ,principles of ,mechanism #hvo1 #c #jj ,schwamb and ,merrill's ,elements of ,mechanism #hvo1 #c #jj ,smith 7,a4 ,w47 and ,marx's ,machine ,design #hvo1 #c #jj ,smith's 7,r4 ,s47 ,manual of ,topographical ,drawing4 #hvo1 #b #ej 7,mc,millan47 99 ,titsworth's ,elements of ,mechanical ,drawing ,oblong #hvo1 #a #be ,tracy and ,north's ,descriptive ,geometry4 7,in ,press47 ,warren's ,elements of ,descriptive ,geometry1 ,shadows1 #hvo1 #c #ej and ,perspective ,elements of ,machine ,construction and ,drawing #hvo1 #g #ej ,elements of ,plane and ,solid ,free-hand #abmo1 #a #jj ,geometrical ,drawing ,general ,problems of ,shades and ,shadows #hvo1 #c #jj ,manual of ,elementary ,problems in the ,linear #abmo1 #a #jj ,perspective of ,forms and ,shadow ,manual of ,elementary ,projection ,drawing #abmo1 #a #ej ,plane ,problems in ,elementary ,geometry #abmo1 #a #be ,weisbach's ,kinematics and ,power of ,transmission4 #hvo1 #e #jj 7,hermann and ,klein47 ,wilson's 7,h4 ,m47 ,topographic ,surveying #hvo1 #c #ej 99 ,wilson's 7,v4 ,t47 ,descriptive ,geometry #hvo1 #a #ej ,free-hand ,lettering #hvo1 #a #jj ,free-hand ,perspective #hvo1 #b #ej ,woolf's ,elementary ,course in ,descriptive ,geometry ,large #hvo1 #c #jj ,,electricity ,,and ,,physics4 99 ,abegg's ,theory of ,electrolytic ,dissociation1 7von #abmo1 #a #be ,ende47 ,andrews's ,hand-book for ,street ,railway ,engineers #c #e #a #be inches mor4 ,anthony and ,ball's ,lecture-notes on the ,theory of #abmo1 #a #jj ,electrical ,measurements ,anthony and ,brackett's ,text-book of ,physics4 7,magie47 ,large #abmo1 #c #jj ,benjamin's ,history of ,electricity #hvo1 #c #jj ,betts's ,lead ,refining and ,electrolysis #hvo1 #d #jj 99 ,burgess and ,le ,chatelier's ,measurement of ,high #hvo1 #d #jj ,temperatures4 ,third ,edition ,classen's ,quantitative ,chemical ,analysis by #hvo1 #c #jj ,electrolysis4 7,boltwood47 99 ,collins's ,manual of ,wireless ,telegraphy and #abmo1 #a #ej ,telephony ,crehore and ,squier's ,polarizing ,photo-chronograph #hvo1 #c #jj 99 ,danneel's ,electrochemistry4 7,merriam47 #abmo1 #a #be ,dawson's 8,engineering0 and ,electric ,traction ,pocket #afmo1 mor4 #e #jj book ,dolezalek's ,theory of the ,lead ,accumulator 7,storage #abmo1 #b #ej ,battery74 7von ,ende47 ,duhem's ,thermodynamics and ,chemistry4 7,burgess47 #hvo1 #d #jj ,flather's ,dynamometers1 and the ,measurement of ,power #abmo1 #c #jj 99 ,getman's ,introduction to ,physical ,science #abmo1 #a #ej ,gilbert's ,de ,magnete4 7,mottelay7 #hvo1 #b #ej 99 ,hanchett's ,alternating ,currents #abmo1 #a #jj ,hering's ,ready ,reference ,tables 7,conversion ,factors7 #afmo1 mor4 #b #ej 99 ,hobart and ,ellis's ,high-speed ,dynamo ,electric #hvo1 #f #jj ,machinery ,holman's ,precision of ,measurements #hvo1 #b #jj ,telescope--,mirror-scale ,method1 ,adjustments1 and #hvo1 #j #ge ,tests4 ,large 99 ,hutchinson's ,high-,efficiency ,electrical ,illuminants ,large #abmo1 #b #ej and ,illumination 99 ,jones's ,electric ,ignition #hvo1 #d #jj ,karapetoff's ,experimental ,electrical ,engineering3 99 ,vol4 ,i4 #hvo1 #c #ej 99 ,vol4 ,,ii4 #hvo1 #b #ej ,kinzbrunner's ,testing of ,continuous-current ,machines #hvo1 #b #jj ,landauer's ,spectrum ,analysis4 7,tingle47 #hvo1 #c #jj ,lob's ,electrochemistry of ,organic ,compounds4 #hvo1 #c #jj 7,lorenz47 99 ,lyndon's ,development and ,electrical ,distribution of #hvo1 #c #jj ,water ,power 99 ,lyons's ,treatise on ,electromagnetic ,phenomena4 #hvo1 each1 #f #jj ,vols4 ,i4 and ,,ii4 99 ,michie's ,elements of ,wave ,motion ,relating to ,sound #hvo1 #d #jj and ,light 99 ,morgan's ,physical ,chemistry for ,electrical #abmo1 #a #ej ,engineers 99 ,norris's ,introduction to the ,study of ,electrical #hvo1 #b #ej ,engineering ,norris and ,dennison's ,course of ,problems on the ,electrical ,characteristics of ,circuits and ,machines4 7,in ,press47 99 ,parshall and ,hobart's ,electric ,machine ,design #dto1 half #ab #ej mor4 ,reagan's ,locomotives3 ,simple1 ,compound1 and ,electric4 ,large #abmo1 #c #ej ,new ,edition 99 ,rosenberg's ,electrical ,engineering4 7,haldane #hvo1 #b #jj ,gee--,kinzbrunner47 99 ,ryan's ,design of ,electrical ,machinery3 99 ,vol4 ,i4 ,direct ,current ,dynamos #hvo1 #a #ej ,vol4 ,,ii4 ,alternating ,current ,transformers4 7,in ,press47 ,vol4 ,,iii4 ,alternators1 ,synchronous ,motors1 and ,rotary ,convertors4 7,in ,preparation47 ,ryan1 ,norris1 and ,hoxie's ,text ,book of ,electrical #hvo1 #b #ej ,machinery ,schapper's ,laboratory ,guide for ,students in ,physical #abmo1 #a #jj ,chemistry 99 ,tillman's ,elementary ,lessons in ,heat #hvo1 #a #ej 99 ,timbie's ,elements of ,electricity ,large #abmo1 #b #jj 99 ,answers to ,problems in ,elements of ,electricity #abmo1 ,paper #j #be ,tory and ,pitcher's ,manual of ,laboratory ,physics ,large #abmo1 #b #jj ,ulke's ,modern ,electrolytic ,copper ,refining #hvo1 #c #jj 99 ,waters's ,commercial ,dynamo ,design #hvo1 #b #jj ,,law4 99 ,brennan's ,hand-book of ,useful ,legal ,information for #afmo1 mor4 #e #jj ,business ,men 99 ,davis's ,elements of ,law #hvo1 #b #ej 99 ,treatise on the ,military ,law of ,united ,states #hvo1 #g #jj 99 ,dudley's ,military ,law and the ,procedure of ,large #abmo1 #b #ej ,courts-martial ,manual for ,courts-martial #afmo1 mor4 #a #ej ,wait's ,engineering and ,architectural ,jurisprudence #hvo1 #f #jj ,sheep1 #f #ej ,law of ,contracts #hvo1 #c #jj ,law of ,operations ,preliminary to ,construction in #hvo1 #e #jj ,engineering and ,architecture ,sheep1 #e #ej ,,mathematics4 ,baker's ,elliptic ,functions #hvo1 #a #ej ,briggs's ,elements of ,plane ,analytic ,geometry4 #abmo1 #a #jj 7,bcher47 99 ,buchanan's ,plane and ,spherical ,trigonometry #hvo1 #a #jj ,byerly's ,harmonic ,functions #hvo1 #a #jj ,chandler's ,elements of the ,infinitesimal ,calculus #abmo1 #b #jj 99 ,coffin's ,vector ,analysis #abmo1 #b #ej ,compton's ,manual of ,logarithmic ,computations #abmo1 #a #ej 99 ,dickson's ,college ,algebra ,large #abmo1 #a #ej 99 ,introduction to the ,theory of ,algebraic ,large #abmo1 #a #be ,equations ,emch's ,introduction to ,projective ,geometry and its #hvo1 #b #ej ,application ,fiske's ,functions of a ,complex ,variable #hvo1 #a #jj ,halsted's ,elementary ,synthetic ,geometry #hvo1 #a #ej ,elements of ,geometry #hvo1 #a #ge 99 ,rational ,geometry #abmo1 #a #ej ,synthetic ,projective ,geometry #hvo1 #a #jj 99 ,hancock's ,lectures on the ,theory of ,elliptic #hvo1 #e #jj ,functions ,hyde's ,grassmann's ,space ,analysis #hvo1 #a #jj 99 ,johnson's 7,j4 ,b47 ,three-place ,logarithmic ,tables3 ,vest-pocket #j #ae size1 paper1 99 #ajj #e #jj copies1 99 ,mounted #j #be on heavy cardboard1 #h #aj inches1 99 #aj #b #jj copies1 ,johnson's 7,w4 ,w47 ,abridged ,editions of ,differential ,large #abmo1 #b #ej and ,integral ,calculus #a vol4 ,curve ,tracing in ,cartesian ,co-ordinates #abmo1 #a #jj ,differential ,equations #hvo1 #a #jj ,elementary ,treatise on ,differential ,calculus ,large #abmo1 #a #ej ,elementary ,treatise on the ,integral ,calculus ,large #abmo1 #a #ej 99 ,theoretical ,mechanics #abmo1 #c #jj ,theory of ,errors and the ,method of ,least ,squares #abmo1 #a #ej ,treatise on ,differential ,calculus ,large #abmo1 #c #jj ,treatise on the ,integral ,calculus ,large #abmo1 #c #jj ,treatise on ,ordinary and ,partial ,differential ,large #abmo1 #c #ej ,equations ,karapetoff's ,engineering ,applications of ,higher ,mathematics3 99 ,part ,i4 ,problems on ,machine ,design ,large #abmo1 #j #ge ,koch's ,practical ,mathematics4 7,in ,press47 ,laplace's ,philosophical ,essay on ,probabilities4 #abmo1 #b #jj 7,truscott and ,emory47 99 ,le ,messurier's ,key to ,professor ,w4 ,w4 ,johnson's ,small #hvo1 #a #ge ,differential ,equations 99 ,ludlow's ,logarithmic and ,trigonometric ,tables #hvo1 #a #jj 99 ,ludlow and ,bass's ,elements of ,trigonometry and #hvo1 #c #jj ,logarithmic and ,other ,tables 99 ,trigonometry and ,tables published separately ,each1 #b #jj ,macfarlane's ,vector ,analysis and ,quaternions #hvo1 #a #jj ,mc,mahon's ,hyperbolic ,functions #hvo1 #a #jj ,manning's ,irrational ,numbers and their ,representation #abmo1 #a #be by ,sequences and ,series 99 ,martin's ,text ,book on ,mechanics4 ,vol4 ,i4 ,statics #abmo1 #a #be 99 ,vol4 ,,ii4 ,kinematics and ,kinetics #abmo1 #a #ej 99 ,vol4 ,,iii4 ,mechanics of ,materials #abmo1 #a #ej ,mathematical ,monographs4 ,edited by ,mansfield ,merriman ,octavo1 #a #jj and ,robert ,s4 ,woodward each ,no4 #a4 ,history of ,modern ,mathematics1 by ,david ,eugene ,smith4 ,no4 #b4 ,synthetic ,projective ,geometry1 by ,george ,bruce ,halsted4 ,no4 #c4 ,determinants1 by ,laenas ,gifford ,weld4 ,no4 #d4 ,hyperbolic ,functions1 by ,james ,mc,mahon4 ,no4 #f4 ,harmonic ,functions4 by ,william ,e4 ,byerly4 ,no4 #f4 ,grassmann's ,space ,analysis1 by ,edward ,w4 ,hyde4 ,no4 #g4 ,probability and ,theory of ,errors1 by ,robert ,s4 ,woodward4 ,no4 #h4 ,vector ,analysis and ,quaternions1 by ,alexander ,macfarlane4 ,no4 #i4 ,differential ,equations1 by ,william ,woolsey ,johnson4 ,no4 #aj4 ,the ,solution of ,equations1 by ,mansfield ,merriman4 ,no4 #aa4 ,functions of a ,complex ,variable1 by ,thomas ,s4 ,fiske ,maurer's ,technical ,mechanics #hvo1 #d #jj ,merriman's ,method of ,least ,squares #hvo1 #b #jj ,solution of ,equations #hvo1 #a #jj 99 ,moritz's ,elements of ,plane ,trigonometry #hvo1 #b #jj ,rice and ,johnson's ,differential and ,integral ,large #abmo1 #a #ej ,calculus4 #b vols4 in one ,elementary ,treatise on the ,differential ,calculus ,large #abmo1 #c #jj ,smith's ,history of ,modern ,mathematics #hvo1 #a #jj 99 ,veblen and ,lennes's ,introduction to the ,real #hvo1 #b #jj ,infinitesimal ,analysis of ,one ,variable 99 ,waterbury's ,vest ,pocket ,hand-book of ,mathematics #b #e #a #jj for ,engineers inches1 mor4 99 ,enlarged ,edition1 ,including ,tables mor4 #a #ej ,weld's ,determinants #hvo1 #a #jj ,wood's ,elements of ,co-ordinate ,geometry #hvo1 #b #jj ,woodward's ,probability and ,theory of ,errors #hvo1 #a #jj ,,mechanical ,,engineering4 ,,materials ,,of ,,engineering1 ,,steam-,,engines ,,and ,,boilers4 ,bacon's ,forge ,practice #abmo1 #a #ej ,baldwin's ,steam ,heating for ,buildings #abmo1 #b #ej ,barr and ,wood's ,kinematics of ,machinery #hvo1 #b #ej 99 ,bartlett's ,mechanical ,drawing #hvo1 #c #jj 99 ,bartlett's ,mechanical ,drawing ,abridged ,ed4 #hvo1 #a #ej 99 ,bartlett and ,johnson's ,engineering ,descriptive #hvo1 #a #ej ,geometry 99 ,burr's ,ancient and ,modern ,engineering and the #hvo1 #c #ej ,isthmian ,canal ,carpenter's ,heating and ,ventilating ,buildings #hvo1 #d #jj 99 ,carpenter and ,diederichs's ,experimental ,engineering #hvo1 #f #jj 99 ,clerk's ,the ,gas1 ,petrol and ,oil ,engine #hvo1 #d #jj ,compton's ,first ,lessons in ,metal ,working #abmo1 #a #ej ,compton and ,de ,groodt's ,speed ,lathe #abmo1 #a #ej ,coolidge's ,manual of ,drawing #hvo1 paper1 #a #jj ,coolidge and ,freeman's ,elements of ,general ,drafting ,oblong #dto1 #b #ej for ,mechanical ,engineers ,cromwell's ,treatise on ,belts and ,pulleys #abmo1 #a #ej ,treatise on ,toothed ,gearing #abmo1 #a #ej ,dingey's ,machinery ,pattern ,making #abmo1 #b #jj ,durley's ,kinematics of ,machines #hvo1 #d #jj ,flanders's ,gear-cutting ,machinery ,large #abmo1 #c #jj ,flather's ,dynamometers and the ,measurement of ,power #abmo1 #c #jj ,rope ,driving #abmo1 #b #jj ,gill's ,gas and ,fuel ,analysis for ,engineers #abmo1 #a #be ,goss's ,locomotive ,sparks #hvo1 #b #jj 99 ,greene's ,pumping ,machinery #hvo1 #d #jj ,hering's ,ready ,reference ,tables 7,conversion ,factors7 #afmo1 mor4 #b #ej 99 ,hobart and ,ellis's ,high ,speed ,dynamo ,electric #hvo1 #f #jj ,machinery ,hutton's ,gas ,engine #hvo1 #e #jj ,jamison's ,advanced ,mechanical ,drawing #hvo1 #b #jj ,elements of ,mechanical ,drawing #hvo1 #b #ej ,jones's ,gas ,engine #hvo1 #d #jj ,machine ,design3 ,part ,i4 ,kinematics of ,machinery #hvo1 #a #ej ,part ,,ii4 ,form1 ,strength1 and ,proportions of #hvo1 #c #jj ,parts 99 ,kaup's ,machine ,shop ,practice ,large #abmo1 #a #be 99 ,kent's ,mechanical ,engineer's ,pocket-,book #afmo1 mor4 #e #jj ,kerr's ,power and ,power ,transmission #hvo1 #b #jj 99 ,kimball and ,barr's ,machine ,design #hvo1 #c #jj 99 ,king's ,elements of the ,mechanics of ,materials and #hvo1 #b #ej of ,power of ,transmission 99 ,lanza's ,dynamics of ,machinery #hvo1 #b #ej ,leonard's ,machine ,shop ,tools and ,methods #hvo1 #d #jj 99 ,levin's ,gas ,engine #hvo1 #d #jj 99 ,lorenz's ,modern ,refrigerating ,machinery4 7,pope1 #hvo1 #d #jj ,haven1 and ,dean7 ,mac,cord's ,kinematics2 or1 ,practical ,mechanism #hvo1 #e #jj ,mechanical ,drawing #dto1 #d #jj ,velocity ,diagrams #hvo1 #a #ej ,mac,farland's ,standard ,reduction ,factors for ,gases #hvo1 #a #ej ,mahan's ,industrial ,drawing4 7,thompson47 #hvo1 #c #ej ,mehrtens's ,gas ,engine ,theory and ,design ,large #abmo1 #b #ej ,miller1 ,berry1 and ,riley's ,problems in ,thermodynamics #hvo1 paper1 #j #ge and ,heat ,engineering ,oberg's ,handbook of ,small ,tools ,large #abmo1 #b #ej 99 ,parshall and ,hobart's ,electric ,machine ,design4 ,small #dto1 #ab #ej half leather1 99 ,peele's ,compressed ,air ,plant4 ,second ,edition1 #hvo1 #c #ej ,revised and ,enlarged 99 ,perkins's ,introduction to ,general ,thermodynamics #abmo4 #a #ej ,poole's ,calorific ,power of ,fuels #hvo1 #c #jj 99 ,porter's ,engineering ,reminiscences1 #ahee to #ahhb #hvo1 #c #jj ,randall's ,treatise on ,heat4 7,in ,press47 99 ,reid's ,mechanical ,drawing4 7,elementary and #hvo1 #b #jj ,advanced47 ,text-book of ,mechanical ,drawing and ,elementary #hvo1 #c #jj ,machine ,design ,richards's ,compressed ,air #abmo1 #a #ej ,robinson's ,principles of ,mechanism #hvo1 #c #jj ,schwamb and ,merrill's ,elements of ,mechanism #hvo1 #c #jj ,smith 7,a4 ,w47 and ,marx's ,machine ,design #hvo1 #c #jj ,smith's 7,o47 ,press-working of ,metals #hvo1 #c #jj ,sorel's ,carbureting and ,combustion in ,alcohol ,large #abmo1 #c #jj ,engines4 7,woodward and ,preston47 ,stone's ,practical ,testing of ,gas and ,gas ,meters #hvo1 #c #ej ,thurston's ,animal as a ,machine and ,prime ,motor1 and #abmo1 #a #jj the ,laws of ,energetics ,treatise on ,friction and ,lost ,work in ,machinery #hvo1 #c #jj and ,mill ,work4 99 ,tillson's ,complete ,automobile ,instructor #afmo1 #a #ej 99 ,titsworth's ,elements of ,mechanical ,drawing ,oblong #hvo1 #a #be ,warren's ,elements of ,machine ,construction and ,drawing #hvo1 #g #ej 99 ,waterbury's ,vest ,pocket ,hand-book of ,mathematics #b #e #a #jj for ,engineers4 inches1 mor4 99 ,enlarged ,edition1 ,including ,tables mor4 #a #ej ,weisbach's ,kinematics and the ,power of ,transmission4 #hvo1 #e #jj 7,herrmann-,klein47 ,machinery of ,transmission and ,governors4 #hvo1 #e #jj 7,hermann-,klein47 ,wood's ,turbines #hvo1 #b #ej ,,materials ,,of ,,engineering4 ,burr's ,elasticity and ,resistance of the ,materials of #hvo1 #g #ej ,engineering ,church's ,mechanics of ,engineering #hvo1 #f #jj ,mechanics of ,solids 7,being ,parts ,i1 ,,ii1 ,,iii of #hvo1 #d #ej ,mechanics of ,engineering7 99 ,greene's ,structural ,mechanics #hvo1 #b #ej ,holley's ,analysis of ,paint and ,varnish ,products4 7,in ,press47 99 ,lead and ,zinc ,pigments ,large #abmo1 #c #jj ,johnson's 7,c4 ,m47 ,rapid ,methods for the ,chemical ,large #abmo1 #c #jj ,analysis of ,special ,steels1 ,steel-,making ,alloys and ,graphite ,johnson's 7,j4 ,b47 ,materials of ,construction #hvo1 #f #jj ,keep's ,cast ,iron #hvo1 #b #ej 99 ,king's ,elements of the ,mechanics of ,materials and #hvo1 #b #ej of ,power of ,transmission ,lanza's ,applied ,mechanics #hvo1 #g #ej ,lowe's ,paints for ,steel ,structures #abmo1 #a #jj ,maire's ,modern ,pigments and their ,vehicles #abmo1 #b #jj ,maurer's ,technical ,mechanics #hvo1 #d #jj ,merriman's ,mechanics of ,materials #hvo1 #e #jj 99 ,strength of ,materials #abmo1 #a #jj ,metcalf's ,steel4 ,a ,manual for ,steel-users #abmo1 #b #jj 99 ,murdock's ,strength of ,materials #abmo1 #b #jj ,sabin's ,industrial and ,artistic ,technology of ,paint #hvo1 #c #jj and ,varnish ,smith's 7,a4 ,w47 ,materials of ,machines #abmo1 #a #jj 99 ,smith's 7,h4 ,e47 ,strength of ,material #abmo1 #a #be ,thurston's ,materials of ,engineering #c vols4 #h #jj #hvo1 ,part ,i4 ,non-metallic ,materials of ,engineering #hvo1 #b #jj ,part ,,ii4 ,iron and ,steel #hvo1 #c #ej ,part ,,iii4 ,a ,treatise on ,brasses1 ,bronzes1 and #hvo1 #b #ej ,other ,alloys and their ,constituents ,waterbury's ,laboratory ,manual for ,testing ,materials of ,construction4 7,in ,press47 ,wood's 7,de ,v47 ,elements of ,analytical ,mechanics #hvo1 #c #jj ,treatise on the ,resistance of ,materials and an #hvo1 #b #jj ,appendix on the ,preservation of ,timber ,wood's 7,m4 ,p47 ,rustless ,coatings3 ,corrosion and #hvo1 #d #jj ,electrolysis of ,iron and ,steel ,,steam-,,engines ,,and ,,boilers4 ,berry's ,temperature-entropy ,diagram4 ,third ,edition #abmo1 #b #ej ,revised and ,enlarged ,carnot's ,reflections on the ,motive ,power of ,heat4 #abmo1 #a #ej 7,thurston47 ,chase's ,art of ,pattern ,making #abmo1 #b #ej ,creighton's ,steam-engine and other ,heat ,motors #hvo1 #e #jj ,dawson's 8,engineering0 and ,electric ,traction #afmo1 mor4 #e #jj ,pocket-book 99 ,gebhardt's ,steam ,power ,plant ,engineering #hvo1 #f #jj ,goss's ,locomotive ,performance #hvo1 #e #jj ,hemenway's ,indicator ,practice and ,steam-engine #abmo1 #b #jj ,economy ,hirshfeld and ,barnard's ,heat ,power ,engineering4 7,in ,press47 ,hutton's ,heat and ,heat-engines #hvo1 #e #jj ,mechanical ,engineering of ,power ,plants #hvo1 #e #jj ,kent's ,steam ,boiler ,economy #hvo1 #d #jj ,kneass's ,practice and ,theory of the ,injector #hvo1 #a #ej ,mac,cord's ,slide-valves #hvo1 #b #jj ,meyer's ,modern ,locomotive ,construction #dto1 #aj #jj ,miller1 ,berry1 and ,riley's ,problems in ,thermodynamics #hvo1 paper1 #j #ge ,moyer's ,steam ,turbine #hvo1 #d #jj ,peabody's ,manual of the ,steam-engine ,indicator #abmo1 #a #ej ,tables of the ,properties of ,steam and ,other #hvo1 #a #jj ,vapors and ,temperature-,entropy ,table ,thermodynamics of the ,steam-engine and ,other #hvo1 #e #jj ,heat-engines 99 ,thermodynamics of the ,steam ,turbine #hvo1 #c #jj ,valve-gears for ,steam-engines #hvo1 #b #ej ,peabody and ,miller's ,steam-boilers #hvo1 #d #jj 99 ,perkins's ,introduction to ,general ,thermodynamics #abmo1 #a #ej ,pupin's ,thermodynamics of ,reversible ,cycles in ,gases #abmo1 #a #be and ,saturated ,vapors4 7,osterberg47 ,reagan's ,locomotives3 ,simple1 ,compound1 and ,electric4 ,large #abmo1 #c #ej ,new ,edition ,sinclair's ,locomotive ,engine ,running and ,management #abmo1 #b #jj ,smart's ,handbook of ,engineering ,laboratory ,practice #abmo1 #b #ej ,snow's ,steam-boiler ,practice #hvo1 #c #jj ,spangler's ,notes on ,thermodynamics #abmo1 #a #jj ,valve-gear #hvo1 #b #ej ,spangler1 ,greene1 and ,marshall's ,elements of #hvo1 #c #jj ,steam-engineering ,thomas's ,steam-turbines #hvo1 #d #jj ,thurston's ,handbook of ,engine and ,boiler ,trials1 and #hvo1 #e #jj the ,use of the ,indicator and the ,prony ,brake ,handy ,tables #hvo1 #a #ej ,manual of ,steam-,boilers1 their ,designs1 #hvo1 #e #jj ,construction1 and ,operation ,manual of the ,steam-engine #b vols41 #aj #jj #hvo1 ,part ,i4 ,history1 ,structure1 and ,theory #hvo1 #f #jj ,part ,,ii4 ,design1 ,construction1 and #hvo1 #f #jj ,operation ,wehrenfennig's ,analysis and ,softening of ,boiler #hvo1 #d #jj ,feed-water4 7,patterson7 ,weisbach's ,heat1 ,steam1 and ,steam-engines4 7,du ,bois47 #hvo1 #e #jj ,whitham's ,steam-engine ,design #hvo1 #e #jj ,wood's ,thermodynamics1 ,heat ,motors1 and ,refrigerating #hvo1 #d #jj ,machines ,,mechanics ,,pure ,,and ,,applied4 ,church's ,mechanics of ,engineering #hvo1 #f #jj ,mechanics of ,fluids 7,being ,part ,,iv of ,mechanics #hvo1 #c #jj of ,engineering7 99 ,mechanics of ,internal ,work #hvo1 #a #ej ,mechanics of ,solids 7,being ,parts ,i1 ,,ii1 ,,iii of #hvo1 #d #ej ,mechanics of ,engineering7 ,notes and ,examples in ,mechanics #hvo1 #b #jj ,dana's ,text-book of ,elementary ,mechanics for ,colleges #abmo1 #a #ej and ,schools ,du ,bois's ,elementary ,principles of ,mechanics3 ,vol4 ,i4 ,kinematics #hvo1 #c #ej ,vol4 ,,ii4 ,statics #hvo1 #d #jj ,mechanics of ,engineering4 ,vol4 ,i4 ,small #dto1 #g #ej ,vol4 ,,ii4 ,small #dto1 #aj #jj 99 ,greene's ,structural ,mechanics #hvo1 #b #ej 99 ,hartmann's ,elementary ,mechanics for ,engineering #abmo1 #a #be ,students ,james's ,kinematics of a ,point and the ,rational ,large #abmo1 #b #jj ,mechanics of a ,particle 99 ,johnson's 7,w4 ,w47 ,theoretical ,mechanics #abmo1 #c #jj 99 ,king's ,elements of the ,mechanics of ,materials and #hvo1 #b #fj of ,power of ,transmission ,lanza's ,applied ,mechanics #hvo1 #g #ej 99 ,martin's ,text ,book on ,mechanics1 ,vol4 ,i1 ,statics #abmo1 #a #be 99 ,vol4 ,,ii4 ,kinematics and ,kinetics #abmo1 #a #ej 99 ,vol4 ,,iii4 ,mechanics of ,materials #abmo1 #a #ej ,maurer's ,technical ,mechanics #hvo1 #d #jj 99 ,merriman's ,elements of ,mechanics #abmo1 #a #jj ,mechanics of ,materials #hvo1 #e #jj 99 ,michie's ,elements of ,analytical ,mechanics #hvo1 #d #jj ,robinson's ,principles of ,mechanism #hvo1 #c #jj ,sanborn's ,mechanics ,problems ,large #abmo1 #a #ej ,schwamb and ,merrill's ,elements of ,mechanism #hvo1 #c #jj ,wood's ,elements of ,analytical ,mechanics #hvo1 #c #jj ,principles of ,elementary ,mechanics #abmo1 #a #be ,,medical4 99 ,abderhalden's ,physiological ,chemistry in ,thirty #hvo1 #e #jj ,lectures4 7,hall and ,defren47 von ,behring's ,suppression of ,tuberculosis4 7,bolduan47 #abmo1 #a #jj 99 ,bolduan's ,immune ,sera #abmo1 #a #ej ,bordet's ,studies in ,immunity4 7,gay47 #hvo1 #f #jj 99 ,chapin's ,the ,sources and ,modes of ,infection ,large #abmo1 #c #jj ,davenport's ,statistical ,methods with ,special #afmo1 mor4 #a #ej ,reference to ,biological ,variations ,ehrlich's ,collected ,studies on ,immunity4 7,bolduan47 #hvo1 #f #jj 99 ,fischer's ,nephritis ,large #abmo1 #b #ej 99 ,oedema #hvo1 #b #jj 99 ,physiology of ,alimentation ,large #abmo1 #b #jj 99 de ,fursac's ,manual of ,psychiatry4 7,rosanoff and ,large #abmo1 #b #ej ,collins47 99 ,hammarsten's ,text-book on ,physiological ,chemistry4 #hvo1 #d #jj 7,mandel47 ,jackson's ,directions for ,laboratory ,work in #hvo1 #a #be ,physiological ,chemistry ,lassar-,cohn's ,praxis of ,urinary ,analysis4 7,lorenz47 #abmo1 #a #jj ,mandel's ,hand-book for the ,bio-,chemical ,laboratory #abmo1 #a #ej 99 ,nelson's ,analysis of ,drugs and ,medicines #abmo1 #c #jj 99 ,pauli's ,physical ,chemistry in the ,service of #abmo1 #a #be ,medicine 7,fischer47 99 ,pozzi-,escot's ,toxins and ,venoms and their #abmo1 #a #jj ,antibodies 7,cohn47 ,rostoski's ,serum ,diagnosis4 7,bolduan47 #abmo1 #a #jj ,ruddiman's ,incompatibilities in ,prescriptions #hvo1 #b #jj ,whys in ,pharmacy #abmo1 #a #jj ,salkowski's ,physiological and ,pathological ,chemistry4 #hvo1 #b #ej 7,orndorff47 99 ,satterlee's ,outlines of ,human ,embryology #abmo1 #a #be ,smith's ,lecture ,notes on ,chemistry for ,dental #hvo1 #b #ej ,students 99 ,whipple's ,tyhpoid ,fever ,large #abmo1 #c #jj 99 ,woodhull's ,military ,hygiene for ,officers of the ,large #abmo1 #a #ej ,line 99 ,personal ,hygiene #abmo1 #a #jj ,worcester and ,atkinson's ,small ,hospitals #abmo1 #a #be ,establishment and ,maintenance4 and ,suggestions for ,hospital ,architecture1 with ,plans for a ,small ,hospital ,,metallurgy4 ,betts's ,lead ,refining by ,electrolysis #hvo1 #d #jj ,bolland's ,encyclopedia of ,founding and ,dictionary of #abmo1 #c #jj ,foundry ,terms used in the ,practice of ,moulding ,iron ,founder #abmo1 #b #ej ,iron ,founder ,supplement #abmo1 #b #ej 99 ,borchers's ,metallurgy4 7,hall and ,hayward47 #hvo1 #c #jj 99 ,burgess and ,le ,chatelier's ,measurement of ,high #hvo1 #d #jj ,temperatures4 ,third ,edition ,douglas's ,untechnical ,addresses on ,technical ,subjects #abmo1 #a #jj ,goesel's ,minerals and ,metals3 ,a ,reference ,book #afmo1 mor4 #c #jj 99 ,iles's ,lead-smelting #abmo1 #b #ej ,johnson's ,rapid ,methods for the ,chemical ,analysis of ,large #abmo1 #c #jj ,special ,steels1 ,steel-making ,alloys and ,graphite ,keep's ,cast ,iron #hvo1 #b #ej ,metcalf's ,steel4 ,a ,manual for ,steel-users #abmo1 #b #jj ,minet's ,production of ,aluminum and its ,industrial #abmo1 #b #ej ,use4 7,waldo47 99 ,palmer's ,foundry ,practice ,large #abmo1 #b #jj 99 ,price and ,meade's ,technical ,analysis of ,brass #abmo1 #b #jj 99 ,ruer's ,elements of ,metallography4 7,mathewson47 #hvo1 #c #jj ,smith's ,materials of ,machines #abmo1 #a #jj ,tate and ,stone's ,foundry ,practice #abmo1 #b #jj ,thurston's ,materials of ,engineering4 ,in ,three ,parts #hvo1 #h #jj ,part ,i4 ,non-metallic ,materials of ,engineering1 see ,civil ,engineering1 page #i ,part ,,ii4 ,iron and ,steel #hvo1 #c #ej ,part ,,iii4 ,a ,treatise on ,brasses1 ,bronzes1 and #hvo1 #b #ej ,other ,alloys and their ,constituents ,ulke's ,modern ,electrolytic ,copper ,refining #hvo1 #c #jj ,west's ,american ,foundry ,practice #abmo1 #b #ej ,moulders' ,text ,book #abmo1 #b #ej ,,mineralogy4 99 ,browning's ,introduction to the ,rarer ,elements #hvo1 #a #ej ,brush's ,manual of ,determinative ,mineralogy4 #hvo1 #d #jj 7,penfield47 ,butler's ,pocket ,hand-book of ,minerals #afmo1 mor4 #c #jj ,chester's ,catalogue of ,minerals #hvo1 paper1 #a #jj ,cloth1 #a #be 99 ,crane's ,gold and ,silver #hvo1 #e #jj ,dana's ,first ,appendix to ,dana's ,new 8,system of ,large #hvo1 #a #jj ,mineralogy40 ,dana's ,second ,appendix to ,dana's ,new 8,system of ,large #hvo1 #a #ej ,mineralogy40 ,manual of ,mineralogy and ,petrography #abmo1 #b #jj ,minerals and ,how to ,study ,them #abmo1 #a #ej ,system of ,mineralogy ,large #hvo1 #ab #ej half leather1 ,text-book of ,mineralogy #hvo1 #d #jj ,douglas's ,untechnical ,addresses on ,technical ,subjects #abmo1 #a #jj ,eakle's ,mineral ,tables #hvo1 #a #be 99 ,eckel's ,building ,stones and ,clays #hvo1 #c #jj ,goesel's ,minerals and ,metals3 ,a ,reference ,book #afmo1 mor4 #c #jj 99 ,groth's ,the ,optical ,properties of ,crystals4 #hvo1 #c #ej 7,jackson47 ,groth's ,introduction to ,chemical ,crystallography #abmo1 #a #be 7,marshall7 99 ,hayes's ,handbook for ,field ,geologists #afmo1 mor4 #a #ej ,iddings's ,igneous ,rocks #hvo1 #e #jj ,rock ,minerals #hvo1 #e #jj ,johannsen's ,determination of ,rock-forming ,minerals in #hvo1 ,with #e #jj ,thin ,sections ,thumb ,index 99 ,martin's ,laboratory ,guide to ,qualitative ,analysis #abmo1 #j #fj with the ,blow-pipe ,merrill's ,non-metallic ,minerals3 ,their ,occurrence and #hvo1 #d #jj ,uses ,stones for ,building and ,decoration #hvo1 #e #jj 99 ,penfield's ,notes on ,determinative ,mineralogy and #hvo1 paper1 #j #ej ,record of ,mineral ,tests ,tables of ,minerals1 ,including the ,use of #hvo1 #a #jj ,minerals and ,statistics of ,domestic ,production 99 ,pirsson's ,rocks and ,rock ,minerals #abmo1 #b #ej 99 ,richardss ,synopsis of ,mineral ,characters #abmo1 mor4 #a #be 99 ,ries's ,clays3 ,their ,occurrence1 ,properties and ,uses #hvo1 #e #jj 99 ,ries and ,leighton's ,history of the ,clay-working #hvo1 #b #ej industry of the ,united ,states 99 ,rowe's ,practical ,mineralogy ,simplified #abmo1 #a #be 99 ,tillman's ,text-book of ,important ,minerals and ,rocks #hvo1 #b #jj ,washington's ,manual of the ,chemical ,analysis of ,rocks #hvo1 #b #jj ,,mining4 99 ,beard's ,mine ,gases and ,explosions ,large #abmo1 #c #jj 99 ,crane's ,gold and ,silver #hvo1 #e #jj 99 ,index of ,mining ,engineering ,literature #hvo1 #d #jj 99 #hvo1 #e #jj mor4 99 ,ore ,mining ,methods #hvo1 #c #jj 99 ,dana and ,saunders's ,rock ,drilling #hvo1 #d #jj ,douglas's ,untechnical ,addresses on ,technical ,subjects #abmo1 #a #jj ,eissler's ,modern ,high ,explosives #hvo1 #d #jj ,goesel's ,minerals and ,metals3 ,a ,reference ,book #afmo1 mor4 #c #jj ,ihlseng's ,manual of ,mining #hvo1 #e #jj 99 ,iles's ,lead ,smelting #abmo1 #b #ej 99 ,peele's ,compressed ,air ,plant #hvo1 #c #ej ,riemer's ,shaft ,sinking ,under ,difficult ,conditions4 #hvo1 #c #jj 7,corning and ,peele47 99 ,weaver's ,military ,explosives #hvo1 #c #jj ,wilson's ,hydraulic and ,placer ,mining4 #b;d edition1 #abmo1 #b #ej rewritten ,treatise on ,practical and ,theoretical ,mine #abmo1 #a #be ,ventilation ,,sanitary ,,science4 ,association of ,state and ,national ,food and ,dairy #hvo1 #c #jj ,departments1 ,hartford ,meeting1 #aijf ,jamestown ,meeting1 #aijg #hvo1 #c #jj 99 ,bashore's ,outlines of ,practical ,sanitation #abmo1 #a #be ,sanitation of a ,country ,house #abmo1 #a #jj ,sanitation of ,recreation ,camps and ,parks #abmo1 #a #jj 99 ,chapin's ,the ,sources and ,modes of ,infection ,large #abmo1 #c #jj ,folwell's ,sewerage4 7,designing1 ,construction1 and #hvo1 #c #jj ,maintenance47 ,water-supply ,engineering #hvo1 #d #jj ,fowler's ,sewage ,works ,analyses #abmo1 #b #jj ,fuertes's ,water-filtration ,works #abmo1 #b #ej ,water and ,public ,health #abmo1 #a #ej ,gerhard's ,guide to ,sanitary ,inspections #abmo1 #a #ej 99 ,modern ,baths and ,bath ,houses #hvo1 #c #jj ,sanitation of ,public ,buildings #abmo1 #a #ej 99 ,the ,water ,supply1 ,sewerage1 and ,plumbing of #hvo1 #d #jj ,modern ,city ,buildings4 ,hazen's ,clean ,water and ,how to ,get ,it ,large #abmo1 #a #ej ,filtration of ,public ,water-supplies #hvo1 #c #jj 99 ,kinnicutt1 ,winslow and ,pratt's ,sewage ,disposal #hvo1 #c #jj ,leach's ,inspection and ,analysis of ,food with ,special #hvo1 #g #ej ,reference to ,state ,control ,mason's ,examination of ,water4 7,chemical and #abmo1 #a #be ,bacteriological7 ,water-supply4 7,considered principally from a #hvo1 #d #jj ,sanitary ,standpoint74 99 ,mast's ,light and the ,behavior of ,organisms ,large #abmo1 #b #ej 99 ,merriman's ,elements of ,sanitary ,engineering #hvo1 #b #jj ,ogden's ,sewer ,construction #hvo1 #c #jj ,sewer ,design #abmo1 #b #jj ,parsons's ,disposal of ,municipal ,refuse #hvo1 #b #jj ,prescott and ,winslow's ,elements of ,water #abmo1 #a #ej ,bacteriology1 with ,special ,reference to ,sanitary ,water ,analysis 99 ,price's ,handbook on ,sanitation #abmo1 #a #ej ,richards's ,conservation by ,sanitation #hvo1 #b #ej ,cost of ,cleanness #abmo1 #a #jj ,cost of ,food4 ,a ,study in ,dietaries #abmo1 #a #jj ,cost of ,living as ,modified by ,sanitary ,science #abmo1 #a #jj ,cost of ,shelter #abmo1 #a #jj ,richards and ,woodman's ,air1 ,water1 and ,food from a #hvo1 #b #jj ,sanitary ,standpoint 99 ,richey's ,plumbers'1 ,steam-fitters'1 and ,tinners' #afmo1 mor4 #a #ej ,edition 7,building ,mechanics' ,ready ,reference ,series7 ,rideal's ,disinfection and the ,preservation of ,food #hvo1 #d #jj ,soper's ,air and ,ventilation of ,subways #abmo1 #b #ej ,turneaure and ,russell's ,public ,water supplies #hvo1 #e #jj ,venable's ,garbage ,crematories in ,america #hvo1 #b #jj ,method and ,devices for ,bacterial ,treatment of #hvo1 #c #jj ,sewage ,ward and ,whipple's ,freshwater ,biology4 7,in ,press47 ,whipple's ,microscopy of ,drinking-water #hvo1 #c #ej 99 ,typhoid ,fever ,large #abmo1 #c #jj ,value of ,pure ,water ,large #abmo1 #a #jj ,winslow's ,systematic ,relationship of the ,coccace ,large #abmo1 #b #ej ,,miscellaneous4 99 ,burt's ,railway ,station ,service #abmo1 #b #jj 99 ,chapin's ,how to ,enamel #abmo1 #a #jj ,emmons's ,geological ,guide-book of the ,rocky ,mountain ,large #hvo1 #a #ej ,excursion of the ,international ,congress of ,geologists ,ferrel's ,popular ,treatise on the ,winds #hvo1 #d #jj ,fitzgerald's ,boston ,machinist #ahmo1 #a #jj 99 ,fritz1 ,autobiography of ,john #hvo1 #b #jj ,gannett's ,statistical ,abstract of the ,world #bdmo1 #j #ge ,haines's ,american ,railway ,management #abmo1 #b #ej ,hanausek's ,the ,microscopy of ,technical ,products4 #hvo1 #e #jj 7,winton7 ,jacobs's ,betterment ,briefs4 ,a ,collection of ,published #hvo1 #c #ej ,papers on ,organized ,industrial ,efficiency ,metcalfe's ,cost of ,manufactures1 and the #hvo1 #e #jj ,administration of ,workshops 99 ,parkhurst's ,applied ,methods of ,scientific #hvo1 #b #jj ,management ,putnam's ,nautical ,charts #hvo1 #b #jj ,ricketts's ,history of ,rensselaer ,polytechnic ,large #abmo1 #c #jj ,institute #ahbd-ahid 99 ,rotch and ,palmer's ,charts of the ,atmosphere for ,oblong #dto1 #b #jj ,aeronauts and ,aviators ,rotherham's ,emphasised ,new ,testament ,large #hvo1 #b #jj ,rust's ,ex-,meridian ,altitude1 ,azimuth and ,star-finding #hvo1 #e #jj ,tables ,standage's ,decoration of ,wood1 ,glass1 ,metal1 etc4 #abmo1 #b #jj ,thome's ,structural and ,physiological ,botany4 #afmo1 #b #be 7,bennett7 ,westermaier's ,compendium of ,general ,botany4 #hvo1 #b #jj 7,schneider7 ,winslow's ,elements of ,applied ,microscopy #abmo1 #a #ej ,,hebrew ,,and ,,chaldee ,,text-,,books4 ,gesenius's ,hebrew and ,chaldee ,lexicon to the ,old ,small #dto1 #e #jj ,testament ,scriptures4 7,tregelles47 half mor4 ,green's ,elementary ,hebrew ,grammar #abmo1 #a #be ---------------------------------------- -------------------------------- ,,transcriber',s ,,notes #a4 ,silently corrected typographical errors4 #b4 ,retained anachronistic and non-standard spellings as printed4 #c4 ,enclosed italics font in underscores4 #d4 ,subscripts are denoted by an underscore before a series of subscripted characters enclosed in curly braces1 e4g4 ,h#b,o4