the eoyal abtillisky institution. 
45 
ON THE COMPARISON OF THE ACCURACY OF GUNS 
+ 
I?T 
ARTILLERY PRACTICE,* 
BY PROFESSOR WILLIAM POLE, F.R.S. 
MEM, INST. C.E, 
MEMBER QE TRE IRON-ARMOUR PLATE COMMITTEE; AND OP THE SPECIAL COMMITTEE FOB 
INVESTIGATING- THE COMPARATIVE MERITS OP 
TME Armstrong and yvhityvorth systems op ripled artillery. 
1. In the first Yolume (1859) of the “Occasional Papers” of the Eoyal 
Artillery Institution, there was published a paper by Captain A. Noble, 
“ On the application of the Theory of Probabilities to Artillery Practice,” 
the principal object of which was to point out a means of defining and 
comparing the accuracy of ordnance of different kinds. At that time rifled 
artillery was scarcely known; but the. great and rapid development it has 
since attained, and in particular the late comparative experiments on guns 
of great accuracy, tried under very varying circumstances, have shewn that 
the problems involved in such comparisons are more intricate than was at 
first anticipated; and I would therefore venture to offer to the Institution a 
few remarks tending somewhat further to elucidate the question. 
It will be well to commence with a brief statement of the system proposed 
by Captain Noble, and to make some allusion to the difficulties which have 
been thought to arise in its application. 
2. The ordinary way of testing a gun for accuracy is to fire a great 
number of rounds from it, with its axis laid always as nearly as possible in 
the same direction; and carefully to register the positions of the various 
shot as they fall on a horizontal plane, 
* I Rave to acknowledge the valuable co-operation of Captain A. Noble, in the preparation of 
this paper. 
The mode here adopted of calculating the probabilities is essentially the same as that given in 
Captain Noble’s paper of 1859, and also in Didion’s “ Traite de Balistique,” 1860. ' I believe, 
however, that the latter work contains, in the part here referred to, some important misprints, 
which, if not corrected, would lead to very serious errors in the practical use pf the formulae. 
[VOL. V.] 7 
