NEW FIELD CARRIAGE (IRON) FOR LONG-RANGE GUNS. 311 
the buffer, supposing it to be of the same size and description as that 
used in the Russian carriage, and of which the compressions and cor¬ 
responding pressures are given in the table. 
The Russian 9-pr., with a velocity of 1200 f.s., has an energy of recoil 
= 12,941 ft. lbs.; and it has been found by experiment that this energy 
causes a compression of 1’52 ins,, reducing it from its initial thickness 
of 3’56 ins. to 2’04 ins.; the corresponding initial pressure being 
10,800 lbs. 
The compression will vary nearly as the energy of recoil; accordingly 
we may say that it will be about 1*6 ins., or the buffer will be reduced 
from 3’56 ins, to 1’96 ins. in thickness. The pressure corresponding 
to this latter compression = 37,200 lbs. nearly. Whence we have the 
following expression for work 
10,800 + 8 , 7 .800 x — 8 200ft. lbs. 
2 12 
This is practically equal to the 3310 ft. lbs., which, as we saw above, 
is the difference between the work done on the carriage in the different 
systems. 
Is, then, 5010 ft. lbs. too great work to put on a carriage of this 
weight (10’6 cwt.) ? It does not appear to be so. The Russian iron 
carriage of 9’64 cwt. supports 3600 ft. lbs., and the German 9 C steel 
carriage of 10*6 cwt. no less than 5422 ft. lbs. 
The work done on a 10’6-cwt. carriage by a 7-cwt.- gun firing a 12-lb. 
shell with 1600 f.s., is more than 5010 ft. lbs.: it is 5480. This is, 
I believe, what it is intended to fire at present. 
The energy of recoil of the gun= 9125 ft. lbs., and that of gun and 
carriage = 3645 ft. lbs., leaving 5480 ft. lbs. as the work expended. 
We thus see that by means of the arrangement described in the pre¬ 
ceding paper, we can fire a 15-lb. shell from a 7-cwt. gun with 1550 f.s. 
and yet strain the carriage less than we do at present. Whether the 
arrangement above described be open to practical objections or not is a 
matter for experiment; but it seems to have stood the test of many 
hundreds of rounds with the most satisfactory results, and fully to have 
attained the object with which it was designed. 
We proceed now to point out what advantages may be expected from 
increasing the weight of shell to 15 lbs. 
The following table shows the velocities of 12 and 15-lb. shells at 
various ranges:— 
Velocity. 
| 
Muzzle. 1000 yds. 
2000 yds. 
| 
3000 yds. 
4000 yds. 
5000 yds. 
12-pr... 
f.s. j f.s. 
1 1600 1 1166 
or + 50 or — 35 
f.s. 
950 
or — 43 
f.s. 
834 
or — 56 
f.s. 
743 
or - 61 
f.s. 
671 
or — 65 
15-pr... 
1550 i 1201 
993 
890 
804 
736 
Thus we see that although the 15-pr. starts with 50 ft. less velocity 
than the 12-pr., yet it has 35 f.s. more at 1000 yds. and no less than 
