DEDUCTIONS FROM SOME FIELD ARTILLERY PRACTICE. 509 
The maximum average effect is produced, not when 
Rule for Elevation ^ e j eva tion i s correct, but when it is too low, so, 
effect** 4 averasfe when selecting the elevation for effect, if the + ’s 
exceed the — ’s, drop the elevation ; but do not raise 
it, if the reverse is the case, unless the — ’s exceed the + ’s by over two 
to one. That the elevation ought on the average to be too low is due 
to the rapid diminution in effect when the elevation is too high. See 
for instance (Fig. II.). 
In applying this rule for corrections of 25 or of 50 yards, (it will not 
work for larger corrections) signs should be reckoned in at the contem¬ 
plated elevation as well as at the elevation at which the shooting is 
taking place. 
For instance supposing we had— 
1900 
1950 
2000 
+ 
supposing also that the time had come to shoot for effect and we 
selected 1950 for our elevation. If we then had two more —’s at 
1950, the —’s at 1950 and at 2000 (the assumed contemplated correc¬ 
tion) would exceed the + ’s at these two elevations by over two to one 
and we should correct to 2000 yards. 
Again, suppose instead of the above we had 
1900 2000 
— 1950 + 
= 2000 
+ 
and we selected 1975 for our elevation. If at this range we had 3 +’s, 
the +’s at 1975 and at 1950 would exceed the —’s at those two ele¬ 
vations and we should correct to 1950. But if we had 3 —’s at 1975 
we should not correct to 2000, for it requires 5 —’s at 1975 and at 2000, 
before the — ’s at those two elevations exceed the 4- ’s by over two to 
one. In fact in applying the rule we look upon two contiguous ele¬ 
vations as one elevation. 
Perhaps one other case will make this matter quite clear. Suppose 
we had:— 
1900 
1950 
1975 
2000 
+ 
it wouid require two more +’s at 1975 to make the +’s at 1975 and at 
^S 0 greater than the —’s at those two elevations. That is two +’s 
would be required before correcting from 1975 to 1950. On the other 
hand it would require four more -’s at 1975 to make the proportion of 
— s at 1975 an .d 2000 exceed the + ’s at those two elevations by over 
two to one. That is 4 —’s would be required before correcting from 
1975 to 2000. The compliance with the rule thus tends to keep the 
elevation low. That is the object in view. 
The question of the time at which it is desirable to cease ordinary 
