TRANSACTIONS OF THE SECTIONS. 221 
upon any part of the plate beyond merely what is necessary; so that the maximum 
result is obtainable with the minimum of pressure. Convex or concave surfaces can 
be as easily printed as plane surfaces. : 
The author describes very fully the different methods in use for the practical 
application of the principle. One great advantage is its extremely simple construc- 
tion, and the small space it occupies relatively to other presses; moreover, a much 
greater number of impressions can be taken in a given time than was possible here- 
tofore. 
As to the sort of pressure to be used; steam, or expanded or condensed air, the 
hydraulic press, the screw, the cam, or the eccentric or knee lever lock. If steam 
is used, the waste heat will warm the plates in copperplate engraving, and will 
thus get rid of the charcoal dust, which is so injurious to the health of the workmen. 
Water, on the whole, appears to be the most desirable agent on account of its 
non-compressibility, and of the small quantity required in order to produce very 
considerable pressure; as also on account of its non-expansibility, which prevents 
the possibility of an explosion; for if any breakage takes place, the water simply 
runs out. ; 
On a Universal Cock. By T. J. S1nBERMAN. 
On a Wreck Intelligencer. By Kt. Smivu. 
It was constructed for the purpose of being thrown overboard in case of wreck 
or any other serious accident. Formed of copper in the shape of a ball, it consisted 
of two hemispherically-shaped shells, coupled together and water-tight, and in- 
tended to contain the ship’s log or other information or valuables. It was painted 
in brilliant colours, and surmounted by a glass ball cut into facets at the top, so as 
to shine in the rays of the sun. 
Remarks on-the Bursting of Guns and Cannon. 
By 8. Smita, FRCS. 
About sixty years ago, the Government sent down to Leeds 1,500 heavy Prussian 
muskets for the volunteers of that day: they were proved by the late Mr. Calvert, 
in a place near School Close. He (Mr. Smith) was then a school Jad, and he and 
his fellow-scholars used to go and see the muskets proved, and they were sadly 
disappointed if some of these old arms did not burst during the trial. When they 
did burst, the barrels used to rise many feet, and describe many somersaults, and 
then he and his fellow-scholars were delighted. From this fact, the conclusion 
would naturally be come to, that where the gun burst at the breech, the force of 
the explosion would be materially diminished, and the aim of the shot altered also. 
His object was to prove that this theory was not correct. Fifty years ago, the 
gardener of Mr. Elam of Sheepscar was brought into the Leeds Infirmary to have 
his arm taken off, and he told this story of his accident:—He (the gardener) said he 
was shooting small birds in the garden, and after firing the last time, he observed 
he had killed two birds. He went to pick them up, and it was only on stooping 
down to do so that he discovered that his hand was hanging down by two or three 
tendons, and that the gun barrel had burst. He (Mr. Smith) made some observa- 
tions about the accident. In the first place, it was singular that the man should 
have his arm blown off, and not know it; and secondly, it struck him as being also 
singular that the birds should be killed, although the gun had burst. Ten or twelve 
years afterwards, when he (Mr. S.) became surgeon at the infirmary, a man em- 
ployed as watchman at Mr. Benyon’s mill, in Meadow-lane, was brought in for 
treatment. The man stated that he was coming off duty about five o’clock in the 
morning, when he saw a crow at the top of a tree seventy yards off. He fired at it, 
saw it drop, and found he had killed it, but the most singular part of the business 
was that his gun had also burst, and evidently after the shot had left it. In 1855, 
a cannon was fired at Woolwich, and the ball was seen to pass from the muzzle of 
the gun, and to strike the butt. The gun afterwards screwed round, burst into 
