58 
MINUTES OF PROCEEDINGS OF 
of shot on the ground, and their average descending angle. It will be 
seen that it is very simple and easy. 
( 1 ) Find the mean range, and take out from the target table, the length 
of the side of test target corresponding thereto, which call a. 
( 2 ) Tind the mean error* in range (as directed in Captain Noble's paper) 
and multiply it by the sine of the descending angle. Call this Jc, and find 
the value of 7 . 
K 
(3) Ihnd similarly the mean error* in lateral deviation, call this and 
fhul l • 
(4) Having these two values, the accuracy of the gun may be found by 
simple inspection of an accuracy table to be constructed for the purpose. 
* To be determined quadratically. If determined lineallj they must each be multiplied by T25. 
