MECHANICAL AND USEFUL ARTS. 19 



mandril or cylinder, and then pulling or extending the coil, so as to 

 .separate, conveying a liquid. Mr. Joule remarks that his object in 

 the novel use or employment of these spiral coils is for the purpose 

 of imparting a rotatory motion to the liquid employed for the purpose 

 of refrigeration or condensation ; such motion producing a beneficial 

 effect by causing each particle of the said liquid to pass over a 

 greater surface, thus necessitating a higher velocity, which prevents 

 the adhesion of a film or layer of liquid to the tube, and promotes a 

 more thorough mixture of the liquid as it circulates, and conse- 

 quently quicker condensation of steam, or vapour, or refrigeration of 

 liquid. He also remarks that the spiral coils may be constructed of 

 any suitable material, and their transverse section may be either 

 square, round, or other convenient form. — Mechanics' Magazine. ■ 



Mr. T.Howard has patented an improvement in Condensing Steam 

 in Engines where Superheated Steam is used. This consists in con- 

 densing steam which is generated in boilers having attached to or 

 combined with them, or with the cylinders or other parts or adjuncts 

 of steam engines, any apparatus or means for superheating the dense 

 steam. The patentee admits such superheated steam, after it has 

 done its duty in the cylinder or otherwise, into a vessel to be con- 

 densed ; but instead of subjecting it to the contact of external cold 

 water, he subjects it to the contact of the same water repeatedly, 

 which is cooled by circulating it, together with that resulting from 

 the condensed steam, through metallic tubes, vessels, or channels, 

 having their opposite surfaces presented in any suitable manner to a 

 current of external cold water, and which, when the supply is limited, 

 should pass in an opposite direction to the water within. The cir- 

 culation of this condensing water is effected by withdrawing it by the 

 ordinary air-pump into the hot cistern, and passing it thence by the 

 atmospheric pressure through the cooling channels again into the 

 condenser, where it is injected amidst the steam continuously, or 

 it may be intermittently, by actuating a valve or injection cock 

 accordingly. The boiler will now be fed by the ordinary means, 

 with the circulating water constantly replenished by that resulting 

 from the condensation of the steam. — Ibid. 



MARINE STEAM-ENGINES. 



Mb. E. Humphrys has patented certain Improvements in Marine 

 Steam-engines. The object here is the arrangement of these steam- 

 engines on what is well known as Wolfe's system, in a more com- 

 pact and convenient form than heretofore. The patentee employs in 

 combination with each low pressure cylinder two high pressure 

 cylinders, which are placed between the end of the low pressure 

 cylinder and the crank shaft. The two high pressure cylinders are 

 mounted on the cover of the low pressure cylinder, one on each side 

 of its piston rod, and the pistons of the high pressure cylinders arc 

 connected with the piston of the low pressure cylinder by rods passing 

 directly from one to the other through the cover of the low pressure 

 cylinder ; thu3 the power generated by the pressure of the steam on 

 B 2 



