United States. War Department. Division of Military Aeronautics

“ All oblique alignment in investigating the range must be absolutely avoided.
Oblique alignment means a line connecting two points on the map and not passing through the horizontal projection of the balloon.
You might be tempted to use an alignment to find the range of an objective after having determined the direction. The process would consist in finding on the map two points so placed that the straight line between them passes through the objective, visualizing this line on the terrain, and placing the objective at the intersection of this visualized line and the direct alignment. ”

“ For the direction, one reference point is enough, because one can consider the alignment of the point as practically parallel to the balloon-target. For the range, 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 himself. ”

“ An intimate knowledge by artillery commanders of the possibilities and limitations of balloon observation.
The limitations of balloon observation are—
1. Distance from the target.
2. Height of observer.
3. Visibility.
Distance from the target is inevitable, but can be lessened by advanced positions and winch tracks.4 During active operation it has sometimes been possible to approach balloons within 4,500 meters (4,921 yards) of the line.
The low height of the balloon compared with an aeroplane is a drawback, as it brings a question of dead ground and exaggerated perspective. ”

“ When an observer holds the glasses in one hand, it is much more difficult for him to correct the movements caused by the balloon and to concentrate on a point. It is very important, therefore, to hold the glasses firmly with both hands, especially when you are making a delicate observation or when 25you wish to study an “objective” in detail.
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PART III.
APPENDIX.
Note 1.—All observations of rounds refer to the line battery target (b-t) and a line perpendicular to same passing through the target. Observations are given in meters right and left and whether the round is over or short. ”

“ Balloon companies should each, as far as possible, be allotted specific artillery organizations. This facilitates telephone communication, prevents duplication of liaison work, and leads to a far more intimate and personal liaison than does any other method. ”

“ In case, on account of dead ground or of a mask before the battery, the observer sees the flashes or the smoke without seeing the battery itself, he should mark the exact alignment in which the flashes or smoke are seen, and determine the bracket in range—that is, the reference points nearest the objective which are clearly over and short. ”

“ Balloon observers must visit batteries frequently, and sometimes be attached for short periods. Shoots should be discussed, especially if unsuccessful. 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 effectively. Similarly, artillery commanders should let balloon observers know of any further targets which they especially wish to engage, as work previously prepared on the ground saves time and gives better results. ”

“ Reporting hostile shelling is a duty for which balloons are especially suitable, as they are favorably situated to observe both the flash of the gun and the fall of the shell. From this information it is possible to direct not only neutralizing fire on the hostile battery, but often also to establish the caliber of the guns and the arc of fire of the battery. ”

“ On the other hand, let both the reference points “a” and “b” (fig. 6) be situated short of the objective O, “a” being nearer the objective and “b” nearer to the balloon. An error aa′ in spotting “a” leads to an error OO′ in the objective greater than aa′. ”

“ Cooperation with aeroplanes.
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PART II.
WORK IN THE BASKET. [Translation of French document, “Instructions au sujet du Travail en Nacelle,” a publication of French G. Q. G., 1918, by Lieut. Kellogg.] ”