THE EOYAL AETILLEEY INSTITUTION. 
175 
150 _ 150 __ 150 7 „ 
’ * A^ 6 - J A% + &c. “ 1188 -*00125 ; 11755 
A1so/ 5 = - (A% - + &o.)* 
= - V,' =g = - 2K S . suppose, = - (1000)3 x 25 x 
Eq" (1), 
§ 8 . 
Eq n (2), 
§ 8 . 
If we were to calculate./ at the other screens we should get different 
results, because A H is not absolutely constant; but after making many 
similar experiments we should find that the value of “ 2b 33 depends on 
the velocity but, is very nearly constant (as has been before remarked) 
for velocities near 1200 f.s. 
Tables, then, are required to give 2 b for all reasonable velocities ; 
but this is so small a quantity (for _ 3 - = -0000001), that it is more 
1501 
convenient to use (1000) 3 x 2b. 
Again, in the course of experiments with different calibres of the 
same class (i.e., spherical or ogival-headed projectiles), it was found 
that 
(1000) 3 x 2 b varied as — 
w 
K 
d 2 
—, suppose. 
In order to make one table serve for all calibres, it is manifestly con- Table (I.) 
w 
venient to tabulate values of Ii — 2b (1000) 3 . ~^ 3 instead of 2b (1000) 3 , 
cl 1 
which would only serve for one calibre. 
Of course A is affected by the above-mentioned fluctuations in the 
value of 2 b. 
In the experiment which forms the subject of this article cl=. 4-92 ins., Art. 55. 
w = 23*84 lbs., 
••• ^(S (1000)3 
28-81 
(4-92) 3 
= 109-1. 
But the density of the air was 1*0076, 
§7, 
*-. reduced value of K = = 108-6. 
1-0076 
This, then, is the number to be tabulated as the value of K, cor¬ 
responding to a velocity of 1276*1 f.s.; but this has been derived from 
one experiment only. The values of K in Table (I.) have been com¬ 
puted from a vast number of experiments undertaken by Mr. Bashforth, 
aided by the officers he mentions. The value, then, that we have just 
obtained naturally does not tally exactly with what we find in the 
table, viz.— 
vel. k. 
1270 . 108-5 
1280 . 108-3 
* Misprints in Bashforth1337 should be 1237 j (A— iVA 4 q) should be — AA 4 ^). 
