THE KOYAL ARTILLERY INSTITUTION. 
337 
19. Cost of projectiles .—This has been stated in a previous paragraph. 
The quantity of lead on one of Mr Britten's shells is about 7 lbs. 12 oz.; 
on one of Mr Jeffery's considerably more, namely, 11 lbs. 3 oz. The adhe¬ 
sion of the lead is satisfactory in both plans, but Mr Britten's projectiles are 
the least susceptible of injury, the base being protected by the wooden disc, 
which expands the lead into the grooves. These projectiles do not require 
turning, which is required by Mr Lancaster's, or planing, which is required 
by Mr Haddan's and Commander Scott's; the two last are, however, on the 
whole, the least expensive of those tried. 
20. Adaptation for firing round shot .—The system which is in itself best 
adapted for firing round shot is Mr Lancaster's; but to judge by results with 
the 9-pr. oval bore 4’2-in. gun (p. 363), it is extremely inaccurate with them, 
so much so that they could not be used with any advantage at ranges beyond 
1000 yds. The Committee have found the shallow grooves of Britten and 
Jeffery, although perhaps somewhat more liable to injury, much more favour¬ 
able to this practice; they only affect the accuracy by increasing the space 
available for the escape of gas, which might, if necessary, be met by a small 
increase of charge; generally, the plan which leaves the largest portion of 
the cylinder untouched, will be the best in this point of view, provided there 
is nothing in the form of groove peculiarly susceptible of injury from an iron 
shot. 
The following Table contains comparative practice in August 1861, with 
a smooth-bore 32-pr., and a shallow-grooved rifled gun (Britten's), both 
firing round shot, with the service charge of 10 lbs. Elevation by spirit- 
level, and the guns 17 ft. above the plane. 
Table X. 
Min. 7302. 
Number of rounds. 
a 
o 
•-§ 
£ 
Time of flight. 
Ranges. 
Mean difference 
of range. 
Mean observed 
deflection. 
Mean reduced 
deflection. 
Min. 
Max. 
Mean. 
° 
" 
yds. 
yds. 
yds. 
yds. 
yds. 
yds. 
Smooth-bored 32-pr.... 
C 20 
2 
3*40 
1027 
1329 
1146 
51-7 
8-1 
2-6 
No. 10,297. 
120 
5 
not 
1823 
2222 
1994 
70*8 
9-8 
8-9 
recorded 
Shallow-grooved 32-pr. 
C 20 
2 
3-59 
1063 
1260 
1172 
32-6 
7-8 
2-7 
No. 24. 
\ 20 
5 
6-59 
1821 
1988 
1882 
24-9 
5-8 
5-8 
The result is decidedly in favour of the rifled gun. This is more than could 
be generally expected, but it makes it probable that little or no disadvantage 
would accrue from the grooving. 
The Committee have not tried it with any other system, but see nothing in 
the different forms of groove to make a material difference in their liability, 
or that of the lands between them, to receive injury. The sectional area of 
the bore of the 32-pr, gun is 31'92 square inches; the area of the section 
