516 
GOLD MEDAL PRIZE ESSAY, 1879 . 
Russian, 
field car¬ 
riage and 
steel. 
riage, since tlie gun starts into motion less quickly. Part, of course, of 
the higher strain caused by quick-burning powder is exerted in 
destructive effect on the material of the gun, but part is not. There 
can be no doubt, we think, that gun and projectile obey the same laws, 
and that a high initial pressure causes the gun to acquire a given 
velocity of recoil in a shorter time than a lower pressure would do. 
This we know to be the case with a projectile, as any velocity curve 
would show us. High pressure in the gun, then, causes a severe strain 
on the carriage—in fact, inflicts a blow rather than a push. The 
quicker, of course, a carriage is put into motion, the more severe is the 
strain on the material composing it. Again, little strain is put on a 
carriage in checking the recoil compared to what is done by the gun 
in putting it into motion. The whole system of gun and carriage 
probably receives its full velocity of recoil before it has moved 2 ins. 
at most. If, by means of a very powerful break, we bring it up in, say, 
4 ft., we only exert a mean pressure of of what it has already under¬ 
gone in being put into motion. 
We mention this fact because it may be thought that the necessity 
for checking the recoil of a gun of the nature proposed would add 
greatly to our difficulties. This is really not the case. 
22. Fortunately, also, just at this time, when it appears that we 
shall have to call upon our carriages to bear far greater strains than 
hitherto, we are aided by improvements in the production of material. 
Steel will help us to solve the difficulty by supplying a material far 
stronger within its elastic limits than wrought-iron. Its ultimate 
tensile .strength, too, is much higher. It is not nearly so easily given a 
permanent set, but recovers its original form after being strained far 
beyond the elastic limits of wrought-iron. Thus, loss of strength from 
loss of form, which often necessitates giving wrought-iron greater 
dimensions and consequent weight than the mere strain put upon it 
requires, is not nearly so much to be dreaded when steel is our material. 
The great objections to steel hitherto—viz., the uncertainty and non¬ 
uniformity of the metal, even when produced under apparently similar 
circumstances, and the deterioration caused by the necessary operations 
of shearing, punching, &c.—appear to have been nearly, if not altogether, 
overcome. 
We are apparently justified, too, in expecting progress in construc¬ 
tion. It must be remembered that the art of iron field carriage con¬ 
struction is as yet in its infancy, not being more than ten years old in 
our service. Moreover, a very ingenious device for reducing the strains 
borne by field carriages has been found successful in Russia. It has 
been adopted for service, according to the “ Revue d'Artillerie 1200 
carriages being ordered on this plan for the new 4-pr., and 500 for the 
new 9-pr. 
This device consists in dividing the carriage into two parts. The 
first consists merely of the trail brackets, with elevating gear, &c., and 
also an elastic buffer. The second consists of the axletree, wheels, 
axletree-seats, two tie-bars (one to each axletree-arm), and a collar-bolt 
passing through a slot cut in the brackets, connecting the rear ends of 
