66 ANNUAL OF SCIENTIFIC DISCOVERY. 



like powder." Gen. Gilmore, the engineer officer in charge of the 

 siege operations, in his official report makes especial mention of 

 James's projectile, and says, " No better piece for breaching can be 

 desired than the forty-two pounder James." 



New American Guns. While the English navy is being armed 

 with guns of very complex structure, those of the American navy 

 have for several years been growing more and more simple. At first 

 the plan of having' ornaments cast upon them was abandoned ; then 

 the enlargements in the form of bands around the muzzle and other 

 parts were dispensed with ; and now, as the last possible step in this 

 direction, they are cast without trunnions, making the cannon a 

 smooth lump of cast iron, without any ridge, corner or projection 

 upon it. This modification is the last improvement introduced by 

 Capt. Dahlgren. He forms the trunnions of gun-metal, cast in con- 

 nection with a strap passing around the breech of the cannon, and 

 secured by a hoop of the same material passing around the cannon 

 near the trunnions. 



It has long been known that corners or angles in the surface of 

 cast iron rendered it much more liable to break* The rollers of roll- 

 ing-mills are now turned with a curve at the shoulder of the journal, 

 it having been found that they were apt to break at this point ; and 

 the introduction of a curve occupying only half an inch in the length 

 of the roller is said to increase the strength about thirty per cent. 



The liability to break at the corners is greatest when the metal is 

 subjected to blows or concussions, and is especially marked in cannon. 

 This has been the reason for dispensing with ornaments and project- 

 ing rings, and for several years our service-guns have been cast with 

 no angles except those at the junction of the barrel with the trunn- 

 ions. It being observed, however, that the guns were very apt to 

 fail at this point, Capt. Dahlgren has devised the above plan of over- 

 coming the difficulty. Scientific American. 



Snyder's Bullet Machine. The product of these celebrated bullet 

 machines, invented by A. B. Snyder, and now used exclusively by the 

 United States Government in their arsenals, appears from official fig- 

 ures to have reached the following extraordinary quantities : Dur- 

 ing a period of nineteen months, or from May 1st, 1861, to December 

 1st, 1862, they produced one hundred million, one hundred and nine 

 thousand ( 100,1 09, ^0) elongated bullets, weighing 5,810 tons. Sny- 

 der's machine is one of the most perfect pieces of mechanism ever 

 produced by American ingenuity. 



Plan for Firing Guns under Water. J. P. Woodbury of Boston 

 has devised the following plan for firing cannon under water. The 

 guns are to be of the usual shape, but much longer than common, and 

 can be cast to discharge any projectile now in use. When ready for 

 action, a tin cylindrical case is fitted closely at the muzzle of the gun, 

 rendering the chamber air-tight and preventing the entrance of water. 

 When fired, the charge attains its full velocity before reaching the 

 canister, and an effective shot may be made at the distance of two 

 or three hundred feet. The cannon is fixed into a stuffing-box simi- 

 lar to that of the piston of a steam-engine, and an automatic port- 

 hole opens and shuts as the gun is run out or withdrawn. It is 



