514 DEDUCTIONS FROM SOME FIELD ARTILLERY PRACTICE. 
beforehand to about ± 200 yards. Gun 12-pr. with Shrapnel with 
head burster. Average number of Percussion Shrapnel for ranging 
6^. Average number of Time Shrapnel for effect I J]/ 2 . 
Fig I. shews that “hits” are only approximately in proportion to 
“ men hit,” when the latter are half, or less than half, of the total num¬ 
ber of men in the target. 
100 hits kill about 30 men, 600 hits no more! but it must be remark¬ 
ed that the trace of the curve above 300 hits is very uncertain. The 
dip of the curve beyond 300 hits illustrates bad distribution, very 
possibly due to too long a fuze. The fact that the curve of “ men hit ” 
is parallel to the line of hits from 200 to 400 hits shows, that unless 
“ hits ” were mere luck, “ men hit ” would be no measure of a battery’s 
efficiency. But the diagrams that follow will show that “ hits ” are a 
measure and a very fairly good measure of accuracy. It follows then 
that “ men hit ” is not a measure of a battery’s shooting under the 
conditions for which the curve has been drawn. Had there been say 
3 or 4 times as many men in the target, or say only half the number of 
rounds fired, then perhaps to have reckoned the score by ‘ men hit ” 
alone would have been fair enough. 
Fig. II. shews— 
(a) That the maximum average effect was produced, not when 
the elevation was exactly determined, but when it was about 12^ yds. 
too low. 
(b) That good effect was obtained when it was from 18 yards too 
high to 3 x 18 yards too low. (The average mean error in determin¬ 
ing the elevation was 18 yards). 
(c) That hits are a much more pronounced measure of accuracy 
in ranging than men hit, for an error of — 100 yards reduces the hits 
by 60%, but the “ men hit ” by only 40% or thereabouts. 
Fig. III. shews— 
(a) The importance of good laying, for the drop of both the 
curves “ men hit ” and “ hits ” is very marked as the error in laying 
increases. 
(b) That “ hits ” are a slightly more pronounced measure of accur¬ 
acy than " men hit,” for an increase of the error from 20 to 40 yards 
decreases the effect in “men hit” by only 25%, while it lowers the 
“hits” by 33% or thereabouts. (The average mean error in laying 
was 25 yards. The term laying error as here used includes the guns’ 
errors). 
Fig. IV. shews— 
(a) The importance of good fuzes well set. A change in the fuze 
error of from 30 to 60 yards reduces “ men hit ” by 25% and “ hits ” by 
about 33%. 
(b) That “ hits ” are a more pronounced measure of accuracy than 
“ men hit ” as far as fuze-setting is concerned. (The mean fuze error 
was 35 yards). 
Fig. V. shews that the Battery Commander cannot range unless the 
laying is good. An increase in the laying error of from 15 to 30 yards 
increased the error in the final elevation ordered from g yds. to 25 yds. 
