390 
FIELD ARTILLERY FIRE. 
The first five columns are taken direct from the range report, the 
sixth column is arrived at as follows :— 
The first round was fired at an elevation of 2000 yards and it fell 
40 yards short of the target, the inference is then, at least as far as 
No. 1 gun is concerned, that the target is 2040 yards distant from 
it. Each round is treated in a similar manner. 
This sixth column must now be carefully examined for badly laid 
rounds, and these can be detected and eliminated as follows:— 
On reference to the range table it appears that 50 per cent, of the 
rounds at this range should fall within a rectangle 21 yards in 
length, and therefore all the rounds should fall within a rectangle of 
84 yards. Now, if we carefully examine column six we shall see that 
a rectangle of 84 yards will include all the rounds with the exception 
of three, viz., rounds 3, 7 and 11, which all went considerably over 
the target. These rounds, moreover, were all from the same gun. 
No. 3, the laying of which requires seeing to, but, as will be shown 
presently, the laying of this gun is very uniform, and the fault most 
probably lies in the Scott - ’s sight being out of adjustment. 
Let us then eliminate these three rounds from the calculation and mark 
them by putting them in brackets. The remaining distances in the 
column are then added together and divided by the number of rounds 
remaining in the calculation. The result is, therefore,, the relative or 
shooting range for the whole battery, less No. 3 gun, and will show us 
how near the Battery Commander really got to the target by the 
ranging process. In this case he accepted the range as 2025 yards. 
The actual relative range, viz., 2045*7 yards, should be compared 
with the range as given by the range-finder, and. the difference 
between the.two is the error of the day. 
Having got the relative range we can now reduce the laying of the 
guns to a common elevation, thus 
Round 1 was fired with an elevation of 2000 yards and was 40 yards 
short; if it had been fired with 2045*7 yards elevation it would have 
gone 45*7 yards further, and thus have been 5*7 yards over instead of 
40 yards short. Each round is referred in a similar manner to the 
elevation 2045*7 yards and the results recorded in columns 7 and 8. 
The result shown by these columns is as if. a largo group of 14 rounds 
had been fired with the elevation 2045*7 yards, and, if we have calcu¬ 
lated the relative range correctly, the sums of the two columns should 
be equal. If the sums of the two columns be added together and 
divided by the number of rounds we shall get the mean error of the 
shooting of the battery, omitting the rounds fired by No. 3 gun ; thus 
86*5 + 86*5 -z~ 10 = 17*3 yards, the mean error, which, multiplied by 
1*67, will give us the 50 per cent, rectangle of the battery. This latter 
should be compared with the 50 per cent, rectangle given in the range- 
table, but it must not be expected that the 50 per cent, rectangle of a 
whole battery can ever be as small as that of a single gun. A well- 
trained battery should not show a greater mean error than 30 yards 
for common shell and 20 yards for shrapnel shell, the latter being much 
the most accurate projectile. 
The mean error of each layer maybe determined in like manner, 
