MECHANICS AND USEFUL ARTS. 45 



Captain Eldridge, of the ship Liverpool, carried this compass from 

 New York to Liverpool and back, and it determined the changing 

 variations during the voyage. We understand a stock company with 

 ample capital has been organized (ui' which Professor James Ren- 

 wick is President) to bring this invention to the notice of the scien- 

 tific minds of Great Britain and the Continent as soon as patents are 

 secured for those localities. Scientific American. 



IMPROVEMENT IN MUSKETS. 



AN important improvement in the manufacture of guns has lately 

 been made in Prussia, but the secret is so strictly guarded by the gov- 

 ernment that it is difficult to ascertain any thing concerning it, though 

 some facts have leaked out. The musket has no lock, and is loaded 

 at the stock end of the barrel. The ball is long, cone-shaped, and 

 rounded at the larger end, while the barrel is slightly rifled ; but the 

 grooves are perfectly straight, and not spiral, as is the case in our 

 guns. By this means, much of the force of the powder, which is 

 usually expended in giving the ball a rotary motion, is saved, and the 

 ball is consequently thrown to a much greater distance. Indeed, it is 

 said that with half the charge used in a percussion musket, it will 

 carry the ball to the mark at a distance of 900 yards. The fire is 

 communicated from the side of the barrel, instead of from the breech, 

 and this is accomplished in the following manner. The portion of 

 the cartridge next the ball is filled with an explosive substance which 

 resembles that used in percussion caps, and this is caused to explode 

 by the contact of a small piece of steel, which passes from the out- 

 side of the barrel through the cartridge, and this contrivance has 

 gained for the gun the name of the " nail-firer." An experienced 

 soldier cannot discharge a percussion gun more than three or four 

 times in a minute, and in the confusion of battle, one is all that can 

 be counted on in that time, while this new gun can easily be dis- 

 charged eight times in a minute. It is evident, that, from the long 

 distance to which it throws the ball, this Prussian gun could be dis- 

 charged many times before an enemy armed with common guns could 

 get within shooting distance. It will be seen, therefore, that if this 

 can really be brought into practical use, it will work a revolution in 

 war. The Prussian government seems to be convinced of its use- 

 fulness, for fifty thousand of them are being manufactured for the 

 army, and some were successfully used in quieting the late insurrec- 

 tion in Baden. London Atlien&um for September 



HARPOON GUN. 



SOME experiments have been lately made near London for the pur- 

 pose of exhibiting the advantages and power of a new harpoon gun, 

 with which some of the South Sea whaling vessels have been provid- 

 ed. To show the simplicity of the invention, the patentee went into 

 a whale-boat and with the very small charge of four drachms of 

 powder projected the harpoon, with a line attached, a distance of 23 



