MECHANICS AND USEFUL ARTS. 95 



cal causes. To remedy these defects as far as possible, a lamp has been 

 invented by Dr. Glover. Instead of the single glass cylinder of the 

 Claimy lamp, a double cylinder was used. The outer cylinder was a 

 quarter of an inch thick, the inner one a good stout glass, a full eighth of 

 an inch thick. The air to feed the flame entered at the top of both, 

 through wire-gauze, and passed downward between them, entering the 

 inner cylinder through gauze. The double cylinder, kept packed as it 

 were together by the gauze, was thus much stronger than a single one 

 would be ; and if either cylinder be broken, the lamp was still a safe lamp. 

 The current between the glasses kept the outer cylinder cool, so that it 

 could always be held in the hand, while a Museler or Clarmy got soon so 

 hot that it would burn the flesh. The light was even superior to the 

 Clanny, owing probably to the more perfect combustion, the air entering 

 the inner cylinder at the bottom. 



IMPROVEMENTS IN FIRE-ARMS. 



Important experiments with new artillery have recently been made in 

 England, in the presence of military and naval commanders. The 

 practice commenced with a sixty-eight pounder gun, ten feet long, and 

 weighing 95 cwt., on Lancaster's principle of the bore, being oval instead 

 of round, which gives the largest guns all the advantages possessed by the 

 best rifle, when shot or shells of a particular description are used. 

 Excellent practice, it is stated, can be made with rifles at considerable 

 ranges ; but until the experiments with Lancaster's oval guns or egg-shaped 

 shells, correct aim could not be taken at the astonishing distance of 5,000 

 yards, the range of the practice with Lancaster's invention. The long 

 period which elapsed during the flight of the destructive projectile, weigh- 

 ing upward of 88 pounds, owing to its elongated form, caused, according 

 to the account given, a feeling of great suspense ; but when it fell at a 

 distance of 5,000 yards, and in no instance did the shells fall wide or short 

 of the target, the spot where it fell and burst presented the appearance of 

 the eruption of a volcano, the sand being raised to a great height in the 

 air. Experiments were also carried on with Moorsom's shells at 3,000 

 yards, and the practice with them and with shot is described as very good. 

 Several other guns have been made of smaller bores, on Lancaster's 

 principle, for the purpose of carrying on experiments with them. 



During the past year, the United States War Department have ordered 

 Maynard's primer and fixtures to be substituted in place of the percussion 

 lock on all muskets hereafter made at the national armories, as also on a 

 part of the old muskets now on hand at the different depositories. Thus 

 the metallic cap, which was of itself a great improvement, is superseded 

 by a still greater one, and will soon go out of use on all fire-arms. 



An improved rifle has recently been invented by Mr. Durell Greene, of 

 Cambridge. Its peculiar excellences consist in its simplicity, in the safety 

 of all its movable parts from the action of the powder, in the superlative 



