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

by United States. War Department. Division of Military Aeronautics

2. OBSERVATION OF A SHOT.

When the shell bursts, take quickly an alignment and reference points in range of the point of burst; spot this point on the map or on the photograph; give its error in reference to the line battery-target, measuring it by the scale on the map or on the photograph. (It is well to put the graphic scale on the photos.)

The delicate part of the operation consists in seeing the shot at the moment of burst. One must try to spot the apex of the inverted cone formed by the burst, 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 immediately. The method of situating the point is the same as that described above.

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. His eyes must never leave the point of burst until he has fixed well in his mind its situation in reference to appropriate reference points. 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 more.

When the observation is direct, the direction of the burst is, of course, known as soon as it is seen. When the observation is lateral, it is well to remember that the line battery-target can not be materialized on the ground because it is in reality an oblique alignment, leading to the same errors which we have discussed. It follows all irregularities of the ground and, on account of this, can not be followed exactly in oblique vision.

Particularly around batteries, the ground is often very irregular. There may even be little spaces of dead ground, caused by hollows which the map does not always show. The above method, applied with the help of photographs, allows you to avoid errors resulting from the existence of these hidden parts.