FIELD ARTILLERY FIRE. 
275 
the French and Grerman batteries at Mars-la-Tonr. The latter, at A, 
were completely puzzled by the ravine in front of the French position. 
This ravine is not visible from the Grerman position, and the first shell 
falling near the far edge of it obscured the French guns and were 
rightly judged short, further shell fired with the same elevation fell 
right down into the steep-sided ravine, and the smoke rising up and 
growing thinner, the French guns were seen through it, and the 
rounds were erroneously judged over; the range of the ravine was 
thus accepted as the correct range of the guns although the latter 
stood several hundred yards in rear of it. In Prince Kraft’s “ 13th 
Letter on Artillery ” he mentions other cases where optical delusions 
have prevented correct observation and the subject is a most impor¬ 
tant one, because unless we have a full grasp of it we shall never be 
able to take full advantage of the concealment offered by the forma¬ 
tion of the ground. This subject is of such importance that it is 
referred to again at the end of this Chapter, under the heading 
“ Concealment versus Protection.” 
Difficulties arising from light, background, mirage, indistinctness of target, 
fyc.—Light and background. The combinations offered by these are 
almost innumerable, but generally speaking when the target is indis¬ 
tinct in a bright light occasional glimpses of it may be obtained when 
clouds pass over or as the smoke of the enemy’s fire rises and veils 
the sun. Whenever possible the position of the target should be 
registered by means of auxiliary marks the same as for laying, and 
every time it re-appears these should be corrected if necessary. 
With a dull light the same precautions should be taken, and advan¬ 
tage taken of bright flashes emanating from it to register the position 
of the target. 
It is under conditions such as the above that a telescope on a tripod 
is invaluable as it can be left laid upon the target. 
Mirage. —In this case the target should be treated as if it were 
altogether an unseen object and the guns should be laid by means of 
auxiliary marks. The fire may often be observed from the nearest 
high ground or from a tree conveniently near the battery; it is not 
always necessary to go to any great elevation in order to be able to 
observe and in minor cases it is sufficient to stand upon a limber 
in order to see the target plainly. 
Indistinctness of target. —This is a difficulty that we are likely to 
suffer from very much in the future owing to the introduction of 
smokeless powder. If the target itself is hardly visible the only way 
out of the difficulty is to register, by means of auxiliary marks, the 
position of the bright flashes occasionally emanating from it. If it 
is not known where to look for these, the furrows made by the enemy’s 
shell and bullets will show the direction from which the fire is coming 
and it will not then be difficult to locate the position of the target. 
Concealment versus Protection. A consideration of the points put 
forward in this Chapter cannot but impress the fact of the great 
benefit to be derived from selecting such a position that the enemy’s 
observation, and therefore ranging, shall be rendered as difficult as 
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