48 ANNUAL OF SCIENTIFIC DISCOVERY. 



IMPROVEMENT IN GUN-CASTING. 



A NEW method has been resorted to at the cannon-foundry near 

 Pittsburg, for the production of guns. Instead of bringing them 

 from the mould solid, and afterwards boring them, they are cast with 

 the proper bore ; the core being carefully prepared so as to inclose a 

 circle of cold water, which it receives and discharges in a continuous 

 current, during the process of cooling, the object, probably, being to 

 chill the inner surface more rapidly than the outer, and thereby give 

 to it a greater density and strength. The plan is the suggestion of 

 Lieutenant Rodman, and two guns one cast on the old and the 

 other on the new plan having been subjected to the usual tests, the 

 first exploded on the 84th, and the latter on the 255th round. This 

 shows a great superiority over the common mode of making cannon, 

 and if future experiments substantiate the successful one, Lieutenant 

 Rodman's invention will come into general use. 



NEW MODE OF MANUFACTURING SHOT. 



MR. SMITH, of the firm of T. Otis Leroy & Co., New York, has 

 invented a new mode of manufacturing shot, which entirely removes 

 the necessity of having the expensive towers now in use. In the 

 ordinary process, the lead, after being dropped, in a fluid state, from 

 a perforated vessel, falls from the top of the tower to its base, and the 

 tower must necessarily be of considerable height in order to give the 

 shot time to cool before reaching the reservoir of water at the bottom. 

 But l>y the new process the liquid lead descends through an upright 

 circular pipe, arranged over a reservoir of water, and near the bottom t 

 is a fan wheel, which produces a constant current of air that meets 

 the lead in its descent, and while it tends to decrease the rapidity of 

 its fall in some degree, it also imparts to it a sufficient degree of cold 

 to solidify the shot effectually, before they reach the reservoir, whence 

 they are transported to the drying table, by means of an endless band 

 of buckets, or elevators. New York Path Finder. 



CHAIN PIPES FOR TELEGRAPHS UNDER WATER. 



MR. WHISHAW presented some links of a full-sized pipe for inclos- 

 ing the wires of electric telegraphs under water. The pipe was 

 formed of links connected together by sockets, each link varying, ac- 

 cording to circumstances, from 18 inches to 24 inches in length, and 

 from 1 inch to 2^ inches internal diameter, according to the number 

 of wires to be inclosed. These pipes, being of wrought-iron, are ex- 

 ceedingly strong, and are required . merely as a protection to the 

 wires, which are previously insulated by means of gutta percha. 

 Pipes of somewhat similar construction are laid under the Rhine and 

 other rivers in Prussia, where the underground system of telegraphs 

 is adopted by the Prussian government (already to the extent of 

 1,200 miles), although many of the railway companies suspend the 

 wires between posts, as practised in England, America, France, &c. 

 'Proceedings of the British Association. 



