224 Miscellaneous Inteliiyence. 



at last succeeded to a degree which had been previously unknown 

 to chronometer makers. The process consists in dipping the part 

 to be divested of magnetism, as a balance-wheel, into line steel 

 filings, and then presenting a fine magnet to the part clothed with 

 filings, at the distance of from one inch to a (Quarter of an inch, ac- 

 cording to the power to be neutralized. It will immediately be per- 

 ceived whether the polarity of the magnet be of the same kind as 

 that in the apparatus ; if so, the filings will gradually fall from the 

 part as the power becomes neutralized. When all the filings have 

 fallen from the part submitted to experiment, dip it again into the 

 filings, to prove whether it has acquired opposite polarity by re- 

 maining too long in the vicinity of the magnet ; if that be the case, 

 present the contrary end of the magnet at a distance in proportion 

 to the power to be diffused. — Trans. Soc. Arts, xliv. 19. 



6. Peculiar Construction of Shot Cartridges. — An ingenious con- 

 struction of shot cartridges has been devised by Mr. Jenour, for the 

 purpose of shooting at much greater distances than can be accom- 

 plished in the present way of discharging guns. It deserves to be 

 examined, audits advantages, if it possess any, proved by repeated 

 experiments, for which reason the following brief account of it is 

 given : — The unwinding of a cord or twine, a chain or wire from a 

 spiral groove infolding the charge of shot, constitutes the chief 

 principle, by means of which they are thrown from the gun in a 

 mass, and dispersed at various distances. Two or more pieces of 

 metal are so constructed as, when bound together by the twine, &c. 

 to form a cylindrical case, inclosing the charge of shot correspond- 

 ing to the size of the gun, and having a regular spiral groove from 

 end to end, similar to a common screw. One end of the twine is 

 made fast, and the other is left free to be unwound by the resistance 

 of the air acting upon it during the passage of the cartridge. The 

 unwinding of the twine being completed, the centrifugal force 

 occasioned thereby opens the case and liberates the contents. One 

 of the subordinate points of the construction is, that of filling the 

 interstices of the charge with fine sand, or other matter, either 

 mixed or not with tallow, in order to prevent the fired powder from 

 penetrating into, and deranging the construction of the cartridge ; 

 and also for the purpose of preserving the spherical form of the shot, 

 whereby the penetrating force is increased. 



The distance to which the shot are to be conveyed in a body is to 

 be regulated by the number of turns, or length of the binding ; 

 also by its specific gravity, texture, and size, and by the charge 

 of powder. The shorter the binding, the less will be the distance 

 to which the shot are conveyed in a body, and vice versa. The 

 case should be of the least possible weight to possess sufficient 

 strength to resist any compression by the action of the discharge, 

 and sliould retain the whole of its contents, until the last turn of the 

 binding is unwound. 



The cartridge cases are formed in two halves, which when put 



