THE ROYAL ARTILLERY INSTITUTION. 
83 
weight of the 16-pr. gun and carriage. A gun of 3‘3-in. calibre might 
be constructed to throw a 16-lb. shell with a charge of 2\ lbs. of 
E.L.Gr. powder, and weighing a little over 10 cwt. instead of 12 cwt.; 
which, taking into consideration a slight reduction in the weight of 
the carriage, would give a clear gain of 3 cwt. in mobility. This 
would reduce the total weight behind team from 41 cwt. to about 
38 cwt., allowing the equipment to remain the same as at present. 
The argument against such a gun would be, “ The trajectory will not 
be so fiat.” But what is gained by having such a flat trajectory ? 
Nothing, at the ordinary ranges of artillery fire, compared with what is 
lost in mobility. The charge of 2Jlbs. of powder would give a muzzle 
velocity of about 1200 f.s., and would strike as hard a blow at 2000 yds. 
as the present 16-pr. gun with a charge of 3 lbs. of E.L.Gr. powder, but 
would have a somewhat higher trajectory. It may be remarked that 
the term, “ a flatter trajectory,” has sometimes a misleading tendency. 
It is a fact which may be easily remembered, that the difference in the 
flatness of trajectory of any field guns is of very little importance, 
although for small-arms, when the ranges are short, it is of great 
importance. Of course I am not now speaking of the comparison of 
two particular guns, for then that which has the flatter trajectory is 
the better of the two (cceteris paribus) ; but I am speaking of efficiency 
in connection with mobility—taking a more comprehensive view of the 
question. For instance, at 5° elevation the range of the service 16-pr. 
is 2228 yds., and time of flight 6*7 seconds, so that the height of the 
trajectory is 4 (6’7) 3 = 179 ft. The 12-pr. B.L. Armstrong gun would 
range about the same distance at 6° of elevation, with a time of flight of 
7*4 seconds. The height, of trajectory of the 12-pr. B.L. would then be 
4 (7‘4) 3 = 219 ft.; and as we are not likely to encounter men 100 ft. 
high, the difference in height is of no importance. The only point of 
importance is the “ longueur battue,” which may be estimated from the 
angle of fall. It is a good rule to remember that the angle of fall is 
about Jrd more than the angle of elevation. This would give 6° 40' as 
the angle of fall of the 16-pr. M.L., and 8° for the 12-pr. B.L., at the 
range of 2228 yds.; and taking the height of a man as 6 ft., the 
dangerous space or ground covered by the former would be 17 yds., by 
the latter 14 yds. A 16-lb. shell, fired with a charge of 2\ lbs. of 
E.L.Gr. powder from a 3’3-in. bore, would cover more ground than the 
12-pr. B.L. at that range; so that the conclusion seems just that at 
2000 yds,, where it would strike as hard a blow as the service 16-pr. 
gun, there would be hardly any practical disadvantage in its higher 
trajectory. Also, the conditions are not the same as in small-arms, 
where <( every bullet has its billet,” but we are considering shell, the 
explosion of which would be felt over a larger area. A muzzle velocity 
of about 1200 f.s. is quite enough for any field gun of ordinary con¬ 
struction, and indeed for any gun where weight is an object. If this 
muzzle velocity* is much exceeded, it is true that some advantage is 
obtained for very short ranges, but not corresponding to the extra 
weight entailed. Thus, it is easy to get a muzzle velocity of 1200 f.s. 
from a 9-pr. of 6 cwt.— i.e., 200 f.s. per cwt. According to this pro¬ 
portion, a muzzle velocity should be obtained from a 9-pr. of 8 cwt. of 
