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large bullets from large rifles should not give results proportionate to 
those obtained from small bullets and small rifles. Colonel Cavalli, the 
able Superintendent of the Sardinian cannon factory, was one of the first 
who grappled with the difficulty. He found, however, that if he used 
more than a very moderate charge of gunpowder, his cannon burst. 
Mr. Lancaster’s experience might be stated in the same words. Mr. 
Joseph Whitworth, perhaps the most successful mechanical engineer 
who ever lived, after rifling some small cannon, which projected bullets 
with accuracy almost incredible, rifled one with a bore of about four 
inches, and sides nine inches thick. Itburst. He tried one with sides 
eleven and a half inches thick. It, too, burst. 
Mr. Bashley Britten, in 1854, discovered a very simple method of 
attaching lead to an iron shot by soldering. His projectile enters a can- 
non easily from the muzzle, and, on the ignition of the gunpowder, the 
lead is forced by the gas to fill the grooved barrel, and give the projec- 
tile the necessary ‘‘spin.” With such shells, Mr. Britten has obtained 
results from old-fashioned cannon far beyond ‘all competition. He has 
rifled several service 32-pounders, and fired 51 1b. shells from them, 
getting a range of upwards of two miles with 10° of elevation, using 
6 lbs. of gunpowder. From service 18-pounders he could fire 28 1b. 
shells with 4 lbs. of gunpowder, getting excellent ranges. He tried 
some 341b. shells and 63lbs. of powder, and the gun burst. Many 
others tried, and minor obstacles were overcome. Either by loading at 
the breech, or by using expanding bullets like Mr. Britten’s, windage 
was avoided; by coating the bullet with lead, or by planing it, excessive 
wear and tear of barrel was prevented ; but progress was barred by the 
difficulty of obtaming cannon of sufficient strength to bear charges of 
powder proportionate to the weight of projectile, until that principle of 
construction was adopted which was first publicly advocated in this room 
by Mr. Robert Mallet on the 25th of June, 1855. As the reasoning of 
Mr. Mallet, and Dr. Hart’s calculations, are to be found in the Trans- 
actions of this Academy, I will only briefly remind you that they 
recommended cannon to be built up tube over tube, each tube compress- 
ing those within it to a degree to be exactly determined by previous cal- 
culation. This compression of the inner tubes, and consequent extension 
of the outer tubes, is necessary, they argued, to prevent the inside break- 
ing before communicating sufficient strain to the outside, as is the case in 
any thick tubes made in one piece. My object in addressing you this 
evening is to mention some facts which will correborate these views. 
Table A gives the dimensions of some cylinders when strained from 
within, as obtained by actual measurement by Major Wade, of the U. S. 
Ordnance. With every degree of strain, it will be observed, the outer 
portions of these cylinders stretched less than the inner ones, and that, 
too, m a greater ratio than any of the received formule would account 
for. Major Wade also burst some cannon for his Government by water- 
pressure, and found their strength to resist pressure from within, in some 
cases, only one-quarter what it would have been had the whole thickness 
shared equally in resistance. 
