,transcriber's ,note3 ,italic text is enclosed in underscores2 boldface text is enclosed in equals signs4 ,subscripts are actual subscript characters4 ,illustration3 7cover7 ,,balloon ,,observation and ,,instructions on the subject of ,,work ,,in ,,the ,,basket ,issued by the ,division of ,military ,aeronautics ,u4,s4 ,army ,a free translation of the ,french booklet 8,instructions au sujet du ,travail en ,nacelle10 and an added discourse on ,balloon ,observations ,illustration ,,washington ,,government ,,printing ,,office ,,august1 #aiah ,,part ,i4 ,,balloon ,,observation4 ,,introductory ,,note4 ,in this pamphlet will be laid down the general principles and also the limitations which govern observation from balloons4 ,balloon observation includes more than actual artillery observation4 7,see 8,employment of ,balloons407 ,the details of cooperation between balloons and artillery are issued from time to time by the ,general ,staff in the form of pamphlets4 ,whatever the system ordered at the time1 there are certain principles which do not change4 ,in artillery observation it can not be emphasized too strongly that success depends both on-- #a4 ,the efficiency of the balloon observers1 including an intimate knowledge of the ground within view4 #b4 ,an intimate knowledge by artillery commanders of the possibilities and limitations of balloon observation4 ,the limitations of balloon observation are-- #a4 ,distance from the target4 #b4 ,height of observer4 #c4 ,visibility4 ,distance from the target is inevitable1 but can be lessened by advanced positions and winch tracks4 ,during active operation it has sometimes been possible to approach balloons within #d1ejj meters 7#d1iba yards7 of the line4 ,the low height of the balloon compared with an aeroplane is a drawback1 as it brings a question of dead ground and exaggerated perspective4 ,visibility is the determining factor of the balloon's usefulness4 ,in very high winds1 very misty or cloudy weather1 observation is impossible1 and owing to its stationary nature the balloon can not1 by any special effort on the part of its observers1 overcome unfavorable conditions in the same way as is possible in the case of aeroplane observation4 ,on the other hand1 a balloon flying at a height of #a1ejj meters 7#a1fdj yards7 and #g1jjj meters 7#g1fea yards7 from the line1 under favorable weather conditions1 combines in a marked degree many of the advantages of air and ground observation4 ,in the first place1 glasses can be used4 ,secondly1 the balloon observer can converse direct with the battery commander by telephone4 ,apart1 therefore1 from ease and certainty in reporting observations1 the telephone system enables an elastic program of work to be drawn up and admits of personal conversation between the battery commander and the observer1 often permitting mistakes or misunderstandings to be cleared up during shoot instead of afterwards4 ,finally1 owing to the continuous nature of his observation from the same spot1 the balloon observer is able to learn his country in the greatest detail and can keep a close watch on suspected roads or areas of country4 ,,liaison ,,between ,,balloons ,,and ,,artillery ,the work of balloons is principally with the artillery1 and close liaison between these two branches is indispensable if the best results are to be obtained4 ,this close liaison should be promoted on the following lines3 7a7 ,balloon companies should each1 as far as possible1 be allotted specific artillery organizations4 ,this facilitates telephone communication1 prevents duplication of liaison work1 and leads to a far more intimate and personal liaison than does any other method4 7b7 ,balloon observers must visit batteries frequently1 and sometimes be attached for short periods4 ,shoots should be discussed1 especially if unsuccessful4 ,observers should prepare and take with them when visiting batteries a list of targets which are clearly visible from the balloon and on which they can observe effectively4 ,similarly1 artillery commanders should let balloon observers know of any further targets which they especially wish to engage1 as work previously prepared on the ground saves time and gives better results4 7c7 ,artillery officers should visit the balloon and make ascents4 ,they will thus become acquainted with the extent of view from the balloon and the ability and difficulties of the observers4 ,,employment ,,of ,,balloons4 ,in view of the above1 the work most suitable for balloons is as follows3 ,,general ,,surveyance ,,of ,,enemy',s ,,activities4 7a7 ,reporting modifications of enemy defensive organization2 detecting movements of convoys and trains4 ,their importance and itineraries1 locating infantry signals1 and all other activities such as revealed by fires1 smokes1 dust1 trails1 etc4 7b7 ,spotting active hostile batteries and reporting hostile shelling4 ,reporting hostile shelling is a duty for which balloons are especially suitable1 as they are favorably situated to observe both the flash of the gun and the fall of the shell4 ,from this information it is possible to direct not only neutralizing fire on the hostile battery1 but often also to establish the caliber of the guns and the arc of fire of the battery4 ,,ranging ,,and ,,adjusting ,,of ,,fire4 7a7 ,observing fire for destruction on all targets1 counterbattery1 or bombardment4 7b7 ,reporting fleeting targets and observing fire on them4 7c7 ,observing for registration fire4 7d7 ,observing fire on the enemy's communications4 7e7 ,cooperation with aeroplanes4 ,,part ,,ii4 ,,work ,,in ,,the ,,basket4 ,translation of ,french document1 8,instructions au sujet du ,travail en ,nacelle10 a publication of ,french ,g4 ,q4 ,g41 #aiah1 by ,lieut4 ,kellogg4 ,the rapidity and precision of the work in the basket depend not only on the natural gifts of the observer1 but also very largely on his methods of work4 ,the object of the following instructions is to tell the student observers the general methods they should follow and to explain the use of these methods4 ,the principal operations which they must be able to execute rapidly are as follows3 #a4 ,orientation and general reconnaissance of the terrain4 #b4 ,spotting points on the ground seen on the map and points on the map seen on the ground4 #c4 ,observation of fire4 ,,chapter #a4 ,,orientation ,,and ,,general ,,reconnaissance ,,of ,,the ,,terrain4 ,this is the operation which the observer executes on his first ascension in a new sector2 this is how it should be conducted4 #a4 ,rapidly look over the terrain around the ascensional point in order to orient the map4 ,this is done by finding in some direction from the ascensional point a line giving an easily identified direction 7a road1 an edge of woods1 etc474 ,orient the map so as to make this line on the map parallel to the line on the ground4 ,the map can also be oriented by means of the compass4 #b4 ,locate the horizontal projection of the balloon4 ,the observer may know already the winch position1 but the balloon is carried off horizontally from the winch sometimes as much as #djj or #ejj meters 7#dcf to #ede yards74 ,thus it is essential not to confuse the winch position with the horizontal projection of the balloon4 ,if this is done1 errors will be made in the operations which we are going to discuss later1 where we make use of this known point4 ,it is pretty hard to materialize definitely the vertical line passing through the basket4 ,the effect of the wind and the movements of the balloon make it impossible to use a plumb line4 ,the observer has to find his projection on the ground by leaning first from one side of the basket and then from the other in order to diminish the chances of error4 ,an approximation of #be or #ej meters is sufficiently accurate for the general reconnaissance which it is necessary to make4 #c4 ,leaving the region beneath the balloon1 acquaint yourself1 step by step1 with the most prominent points in different directions--masses of woods1 villages1 etc4 ,there are two methods--by the process of cheminement or tracing landmarks and by the process of direct alignment4 ,the process of 8cheminement0 or tracing consists in following outlines1 such as roads1 streams1 or hedges1 identifying as you go along details of the terrain which these lines pass through or near4 ,on account of the deformations due to the effect of perspective and to the unevenness of the ground1 and particularly on account of the deformation of angles1 if it is a winding road1 this method often leads to errors2 it should be employed only in certain cases defined below3 ,the process of 8direct alignment0 consists of studying the terrain by following successive directions from the balloon position4 ,we call the 8alignment0 of a point the trace1 on the terrain1 of the vertical plane passing through this point and through the eye of the observer2 in perspective vision1 when the observer determines the point in question1 this alignment would appear to him a vertical line4 ,on the map it is nothing more than the straight line joining the point under consideration to the vertical projection of the balloon4 ,the method of alignment1 then1 consists in first identifying the most prominent points near the balloon and finding1 by cheminement or tracing1 the lines running from these points4 ,a point found directly by cheminement should not be considered as definitely determined until its alignment has been verified4 ,this first reconnaissance is not to study the terrain in all its details1 but only to fix in the memory a certain number of prominent points scattered throughout the sector in order to facilitate later work4 ,these points should be very distinct1 visible to the naked eye1 and of characteristic forms1 so that there will be no danger of confusing them with others--masses of woods1 important villages1 etc4 ,roads with borders of trees1 large paths for hauling supplies1 when taken together1 are very valuable for quickly finding others4 ,,chapter ,,ii4 ,,spotting ,,of ,,points4 ,generalities4--,in all spotting operations1 whether working from the map to the terrain or vice versa1 the difficulty is due to the fact that the situation of the point has to be found on a two-dimension surface4 ,the best method of work will be1 then1 that which suppresses as quickly as possible one of these dimensions and to conduct the research on a straight line4 ,any point can be placed on the terrain or on the map if you know the following elements3 #a4 ,its 8direction0 or alignment4 #b4 ,its situation on this alignment--that is1 its 8range40 ,in oblique vision1 a digression in direction is always much more apparent than a digression of the same size in range4 ,thus the direction of a point can be identified with more facility and precision than its range4 ,for these reasons1 the following methods consider two distinct phases in all spotting operations3 #a4 ,investigation of direction4 #b4 ,investigation of range4 ,the investigation in direction always comes first1 as it is easier1 and its result makes the investigation for range easier4 ,,locating ,,on ,,the ,,ground ,,an ,,object ,,seen ,,on ,,the ,,maps4 ,if it is a question of a very visible point 7cross-roads1 an isolated house1 a corner of woods1 etc471 the spotting can be done almost immediately1 it was found in the general reconnaissance of the terrain1 which was discussed in chapter #a4 ,if1 on the contrary1 the point under consideration is difficult to find 7a piece of trench in a confused and cut-up region1 a battery emplacement1 etc471 we must have recourse to a precise method4 #a4 ,,research ,,in ,,direction4 ,join on the map the projection of the balloon and the center of the objective4 ,identify this direction on the terrain by finding on the alignment a prominent point4 ,this line can be drawn in the basket4 ,it is a good thing to draw the alignment on a vertical photograph of the objective also1 in order to have a greater number of reference points than the map could give4 #b4 ,,investigation ,,of ,,range4 ,identify on the map 7or photo7 two points1 one situated over and one short of the objective4 ,narrow down this bracket step by step until the object is recognized4 ,as this investigation of the range is the more difficult1 observers must be warned against certain methods which are to be absolutely avoided-- #a4 ,never identify the range of a point by comparing it with that of a near-by point situated on a different alignment4 ,if these two points are not at exactly the same height1 the deformations due to oblique vision can falsify their apparent relative range4 ,the point farthest away can even seem nearer1 and the nearest point farther away4 ,illustration3 ,fig4 #a ,fig4 #b ,,example 7fig4 #a74--,suppose there are two trees1 ,a and ,b1 ,a being nearer the balloon and higher than ,b4 ,it can happen that1 in oblique vision 7fig4 #b71 ,b having its image ,b and ,a its image ,a1 the depression of the image ,b is more than that of ,a4 ,in this case1 the observer will be tempted to believe that the tree ,b is nearer him than the tree ,a4 #b4 ,all oblique alignment in investigating the range must be absolutely avoided4 ,oblique alignment means a line connecting two points on the map and not passing through the horizontal projection of the balloon4 ,you might be tempted to use an alignment to find the range of an objective after having determined the direction4 ,the process would consist in finding on the map two points so placed that the straight line between them passes through the objective1 visualizing this line on the terrain1 and placing the objective at the intersection of this visualized line and the direct alignment4 ,this result1 which would be accurate if the ground were absolutely flat1 is made erroneous by the unevenness of the terrain4 ,on account of this1 the oblique alignment does not pass1 in oblique vision1 through the same points as its horizontal projection on the map4 ,illustration3 ,fig4 #c ,,example 7fig4 #c74--,on the map ,c is the objective1 ,a and ,b two points so situated that the line ,,ab passes through ,c1 and ,,ef the direct alignment1 or the line balloon objective4 ,the line ,,ab coincided on the terrain1 with the trace of the vertical plane passing through ,a and ,b4 ,in oblique vision 7fig4 #d7 it is different4 ,the line ,a,c,b is a curve which follows the irregularities of the ground1 and the point ,c is not on the oblique alignment ,a,b4 ,illustration3 ,fig4 #d ,,locating ,,on ,,the ,,map ,,an ,,object ,,seen ,,on ,,the ,,ground4 #a4 ,determine first on the map the approximate region where the objective is seen4 ,a result which you can obtain very quickly1 thanks to the points which you had found in your first reconnaissance of the terrain4 #b4 ,investigation of direction4 ,this operation consists in determining the alignment of the objective4 ,as this alignment is a straight line1 you only have to know two points4 ,one of them could be the horizontal projection of the balloon2 but you must realize that this position is always changing a little1 and it is hard to determine it with absolute precision4 ,it is better to carry on the operation independent of this position1 which means applying the following method3 ,choose on the alignment of the center of the objective two points1 one over and one short1 and easily identifiable on the map4 ,draw with a pencil in the region of the objective the alignment thus obtained4 ,these points should be1 as far as possible1 precise details of the terrain1 such as a corner of woods1 an angle of a house1 a place where roads or trenches cross1 an isolated tree1 etc4 ,when the alignment of the objective does not pass through any such points1 the difficulty can be overcome by determining in what proportions it cuts a known element1 such as an edge of woods or a hedge1 provided this element is plainly perpendicular to the direction of observation4 ,this direction can be approximated to the extent of the thickness of the pencil mark4 ,on its accuracy the final result depends4 ,the difficulty lies in materializing the alignment--that is1 the vertical line through the center of the objective--in order to lessen the chances for mistakes4 ,student observers should have frequent practice in this exercise4 ,when the point to be found is near the edge of the map it is sometimes necessary to take both reference points between the balloon and the objective2 this should be avoided as much as possible1 because it is apt to be less exact than when the objective is bracketed by its reference points4 ,thus 7fig4 #e71 two reference points ,a and ,b determine the alignment ,,ab1 ,o1 the objective1 is situated at some point between ,a and ,b4 ,an error ,,aa in the spotting of one of these points leads to a smaller error in the position of the objective ,,oo--that is1 smaller than ,,aa4 ,illustration3 ,fig4 #e ,fig4 #f ,on the other hand1 let both the reference points 8a0 and 8b0 7fig4 #f7 be situated short of the objective ,o1 8a0 being nearer the objective and 8b0 nearer to the balloon4 ,an error aa in spotting 8a0 leads to an error ,,oo in the objective greater than aa4 ,notice that this error diminishes as 8,a0 approaches ,o1 thus 8a0 being as a1 the error aa equal to aa leads to an error ,,oo1 in the objective1 less than ,,oo4 ,we would thus obtain an analogous result if we would move the point 8b0 farther away4 ,therefore1 when you are obliged to take the two reference points between you and the objective1 choose one as near the objective as possible and the other as near as possible to the balloon4 #c4 ,investigation of range4 ,identify details of the terrain situated over and short of the objective on the alignment4 ,narrow this bracket down step by step2 situate the objective on the map according to its relative distance from the two nearest identifiable reference points1 taking into account the deformations due to the laws of perspective and the relief of the ground4 ,if you have a vertical photograph of the region1 trace the alignment on this photograph and make the investigation in range by the same means4 ,the dangers against which ,i warned you before in connection with the investigation of range apply in this case also1 so it is unnecessary to repeat them4 ,when the two last identifiable reference points are some distance from each other1 the situation of the objective has a possible error1 of which you know the size according to the distance between the two reference points2 it might be interesting to remember this in case different information is obtained on this objective from that obtained in the balloon4 ,this error can be considerably diminished if you use a vertical photograph2 the investigation can then be carried on by the same method as on the map1 with greater precision4 ,in the case of a battery1 particularly1 it is for the observer to find the position of each piece4 ,in case1 on account of dead ground or of a mask before the battery1 the observer sees the flashes or the smoke without seeing the battery itself1 he should mark the exact alignment in which the flashes or smoke are seen1 and determine the bracket in range--that is1 the reference points nearest the objective which are clearly over and short4 ,this document compared with other information can facilitate the identification of the battery4 ,,chapter ,,iii4 ,,observation ,,of ,,fire4 ,the observation of fire is essentially the following operation1 repeated for each shot or salvo3 ,locating on the ground the position of one point1 which is the point of burst1 and announcing its situation in reference to another point1 which is the target4 ,but it has been demonstrated that it is impossible1 without using the map1 to determine the error in range of one point relatively to another point not on the same alignment4 ,the operation must consist in3 #a4 ,spotting on the map the point of burst4 #b4 ,reading its position in reference to the target4 ,the observation of the burst--that is1 the spotting of the point of impact--is the same whether the observation is direct or lateral4 #a4 ,,preparation ,,of ,,the ,,fire4 ,draw on the map1 and copy if possible on a vertical photograph1 the line balloon target 7alignment of the center of the objective7 and draw through this point a perpendicular to the alignment4 ,in case the observation is lateral1 draw also the line battery target and its perpendicular4 ,to draw the line balloon target1 it is not necessary to know the horizontal projection of the balloon4 ,it is enough to find on the ground a point situated directly on the alignment of the center of the objective4 #b4 ,,observation ,,of ,a ,,shot4 ,when the shell bursts1 take quickly an alignment and reference points in range of the point of burst2 spot this point on the map or on the photograph2 give its error in reference to the line battery-target1 measuring it by the scale on the map or on the photograph4 7,it is well to put the graphic scale on the photos47 ,the delicate part of the operation consists in seeing the shot at the moment of burst4 ,one must try to spot the apex of the inverted cone formed by the burst1 without paying any attention to the more or less considerable cloud of smoke which follows and which will cause mistakes if the burst was not seen immediately4 ,the method of situating the point is the same as that described above4 ,for the direction1 one reference point is enough1 because one can consider the alignment of the point as practically parallel to the balloon-target4 ,for the range1 a rapid study of the terrain before the fire is sufficient to allow the observer to know the reference points by which he can guide himself4 ,his eyes must never leave the point of burst until he has fixed well in his mind its situation in reference to appropriate reference points4 ,not to do this would lead to errors and to loss of time while he has to find the point again with his glasses to study it some more4 ,when the observation is direct1 the direction of the burst is1 of course1 known as soon as it is seen4 ,when the observation is lateral1 it is well to remember that the line battery-target can not be materialized on the ground because it is in reality an oblique alignment1 leading to the same errors which we have discussed4 ,it follows all irregularities of the ground and1 on account of this1 can not be followed exactly in oblique vision4 ,particularly around batteries1 the ground is often very irregular4 ,there may even be little spaces of dead ground1 caused by hollows which the map does not always show4 ,the above method1 applied with the help of photographs1 allows you to avoid errors resulting from the existence of these hidden parts4 ,,practical ,,advice4 #a4 ,work sitting down1 with the map on your knees and leaning against the edge of the basket4 ,this position is preferable to all others1 because it allows the observer-- 7a7 ,to correct with his head and shoulders the movements of the basket4 7b7 ,to have the map always before him4 ,he can consult it at any moment1 mark the necessary alignments without loss of time1 use it as a desk for drawing or taking notes1 or as a wind shield when looking at photographs4 ,the observer who works standing up must either pick up his map from the bottom of the basket every time he needs it1 which is out of the question1 or fasten it outside the basket2 the latter solution is inadvisable1 it necessitates working in the wind when the map is referred to1 and every time the observer turns to look at his map he disturbs the equilibrium of the basket4 ,it is advisable to work standing up only on days when there is practically no wind1 and the balloon is continually turning and never becomes oriented4 #b4 ,have always within reach a flat rule1 a pencil1 and a duodecimeter rule4 ,to be able to trace an alignment on the map with precision1 the rule must rest on a firm surface4 ,this happens when the map is mounted on a drawing board2 when it is mounted on a frame with rollers1 the frame should have1 between the two thicknesses of the map1 a board level with the edges of the frame on which the rule can slide with its whole length on the map4 ,with a hard pencil1 well sharpened1 precise and neat alignments can be drawn4 ,the duodecimeter rule is for measuring distances on photographs and on the map2 chiefly in observations of fire4 #c4 ,hold the field glasses with both hands4 ,this advice1 sometimes ignored by observers without expedience1 has a great influence on the accuracy of information4 ,when an observer holds the glasses in one hand1 it is much more difficult for him to correct the movements caused by the balloon and to concentrate on a point4 ,it is very important1 therefore1 to hold the glasses firmly with both hands1 especially when you are making a delicate observation or when you wish to study an 8objective0 in detail4 ,,part ,,iii4 ,,appendix4 ,,note #a4--;,all observations of rounds refer to the line battery target 7b-t7 and a line perpendicular to same passing through the target4 ,observations are given in meters right and left and whether the round is over or short4 ,indications as to deflection are given before those of range4 ,indications as to the amount of error precede those as to the sense of the error4 ,example1 #ej meters 8,right10 8over40 ,owing to the dispersion of fire when adjusting fire for field artillery or howitzer1 it is unnecessary and of little value to the battery to give the amount of the error in range except when asked for by the battery commander or when the error in range is abnormal 7over #bjj meters74 ,when the target is clearly visible and the effect of a round hitting a target is evident1 the observation 8,target0 is reported4 ,unless the observer is certain of having seen the bursts 8,unobserved0 will be sent4 ,if1 however1 after a few seconds smoke can be seen rising from trees1 houses1 etc41 in proximity to the target1 the observation 8,unobserved1 but smoke seen rising left and over10 may be given4 ,,note #b4--,observers must beware of being over-confident in their own powers of observation4 ,true confidence only comes with experience1 and this is best attained by making ascents with a trained observer when ranging a battery and checking one's own observations with those given by him4 ,an observation must never be given unless the observer is quite certain as to its correctness4 ,it is essential to good results that the artillery may be able to rely absolutely on the observations sent down4 ,the observer must watch the target but must avoid straining his eyes by putting up his glasses as soon as a round is fired4 ,he should arrange for the chart room to inform him when a shell is about to fall4 ,the latter must know the time of flight4 ,observers must learn to distinguish readily the bursts of different kinds of shells4 ,,note #c4--;,if the balloon-target line makes an angle with the battery-target line of more than #cj with field artillery and #bj with heavy1 the balloon position will be given to the battery1 and all observations will be given with reference to the balloon-target line and the battery will replot accordingly4