Balloon observation, and instructions on the subject of work in the basket

by United States. War Department. Division of Military Aeronautics

The observer who works standing up must either pick up his map from the bottom of the basket every time he needs it, which is out of the question, or fasten it outside the basket; the latter solution is inadvisable, it necessitates working in the wind when the map is referred to, and every time the observer turns to look at his map he disturbs the equilibrium of the basket.

It is advisable to work standing up only on days when there is practically no wind, and the balloon is continually turning and never becomes oriented.

2. Have always within reach a flat rule, a pencil, and a duodecimeter rule.

To be able to trace an alignment on the map with precision, the rule must rest on a firm surface. This happens when the map is mounted on a drawing board; when it is mounted on a frame with rollers, the frame should have, between the two thicknesses of the map, a board level with the edges of the frame on which the rule can slide with its whole length on the map.

With a hard pencil, well sharpened, precise and neat alignments can be drawn.

The duodecimeter rule is for measuring distances on photographs and on the map; chiefly in observations of fire.

3. Hold the field glasses with both hands.

This advice, sometimes ignored by observers without expedience, has a great influence on the accuracy of information. 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 you wish to study an “objective” in detail.

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. Indications as to deflection are given before those of range. Indications as to the amount of error precede those as to the sense of the error. Example, 50 meters “Right,” “over.” Owing to the dispersion of fire when adjusting fire for field artillery or howitzer, 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 (over 200 meters).