MECHANICS AND USEFUL ARTS. 107 



The Albert Medal. — This medal, which was instituted to *' reward 

 distinguished merit in promoting arts, manufactures, or com- 

 merce," has this year been awarded by the Council of the Society 

 of Arts, to Joseph Whitworth, of Manchester. 



Mosaic Gold. — Bisulphuret of tin forms gold-colored, translu- 

 cent scales, of a peculiar soapy feeling. It is largely employed 

 in bronzing wood. The following is a description of its mode of 

 preparation from tin scraps : Put the scraps in glazed pots, cover 

 them with muriatic acid, and when the tin is all taken up, transfer 

 the liquid into another vessel. Should it yet contain free acid, 

 add new scraps. Then immerse copper plates in the liquid ; the 

 tin will thus by galvanic action precipitate upon them as a spongy 

 mass. Collect the tin, wash it with water, dry it and mix it inti- 

 mately with equal parts of sulphur and sal-ammoniac ; put the 

 mixture into glass retorts, and heat them up gradually on a sand 

 blast. The bronze is obtained partly as a sublimate, partly at the 

 bottom of the retort. 



A NEW VESSEL OF WAR. 



Mr.* John Elder, of the firm Randolph, Elder, & Co., in Glas- 

 gow, has recently patented a most original form of iron-clad ram 

 for coast defences and attacks on sea fortifications. Mr. Elder's 

 vessel is formed below the water-line as a segment of an enor- 

 mous sphere, say 25 feet deep and 200 feet in diameter, of the cir- 

 cular water-line. This corresponds to a small piece of a sphere, 

 of which the versine over a chord of 200 feet is 25 feet long. Over 

 the water-line the armor-clad sides are a short truncated cone, 

 and in the centre of this circular deck a high castle or tower, car- 

 rying 3 or 4 tiers of guns, is arranged. This vessel, being per- 

 fectly circular in plan, has neither bow nor stern, nor anything of 

 the steering attributes of ships now in existence ; it bears, in fact, 

 the same relation of outline and form to the ordinary ships as the 

 form of a crab bears to that of a fish. The power of locomotion is 

 given to this craft by the reaction propeller. The reaction-wheel 

 — probably Mr. Randolph's improved water-jet propeller — is 

 placed in the centre of the vessel, at the lowest point of the spheri- 

 cal segment, and the ejection of water can be effected through 4 

 openings placed at 4 equidistant points in the circumference, so 

 as to command the direction of propulsion without any steering 

 arrangement by forcing the water through 1 or 2 of the passages 

 which command any one of the 4 quadrants enclosed by them. 

 There are, however, steering or deflection-boards fitted to the end 

 of the passages through which the water is ejected ; and, by using 

 these boards, a rotary motion can be given to the "crab." By 

 ejecting the water from 2 opposite passages, or from all 4 passages 

 simultaneously, and placing the steering-boards in a correspond- 

 ing position, the total engine power of the vessel can be made 

 available for setting the ship into a revolving movement round its 

 own vertical axis. The velocity which the ship is capable of at- 

 taining under these conditions, measured at the outer circumfer- 



