28 ANNUAL OF SCIENTIFIC DISCOVERY. 



stream a distance of 2 miles in 20 minutes, equal, allowing for the 

 strength of the current, to 8 miles an hour. The engine weighs con- 

 siderably less than 1 cwt. to each horse-power, and requires much 

 less fuel than the ordinary engines, and is so easily set in motion, 

 graduated to any velocity, or stopped, that a hoy of 12 years of age 

 might manage it with one hand. The best judges have pronounced 

 a high opinion of its capabilities, after witnessing its performances. 

 Captain Fitzmaurice makes no secret of the invention, but shows its 

 interior freely, as it is intended for the public service. An engine of 

 100 horse-power on Captain Fitzmaurice's construction would only 

 occupy a space of 4 feet by 2 feet. 



HIGH-PRESSURE STEAM IN MARINE ENGINES. 



IN answer to some questions from the Admiralty, with reference to 

 the employment of high-pressure steam, working expansively in 

 marine engines, Mr. J. Seaward has submitted a long paper, which 

 closes as follows : " The highest pressure of steam that we have in 

 any case put upon a marine boiler of our own construction, was about 

 161bs. to the square inch; but we are not inclined to repeat the ex- 

 periment, as we feel assured that we can obtain equally good results 

 with steam of a lower pressure. From 10 to 121bs. is the usual 

 pressure we employ in the merchant service for engines and boilers of 

 comparative small power. The steam pressure at present employed 

 in the service is about 81bs. per square inch. We consider steam 

 of this pressure to be well adapted for the exigencies of the service ; 

 we believe it is calculated to secure all the important advantages of 

 power, and economy of weight and space, in a very eminent degree ; 

 these advantages will, in some respects, be slightly increased by aug- 

 menting the steam pressure to 10 or 12lbs. to the square inch. We 

 strongly recommend that the steam employed in the navy should not 

 be of greater pressure than 10, or in extreme cases, 12lbs. ; any ma- 

 terial increase to the latter pressure will be attended with consider- 

 able risk without any adequate advantage." These remarks do not 

 apply to the use of high-pressure non-condensing engines, London 

 Atherucum* 



THE CHLOROFORM STEAM-ENGINE. 



THE " Combined Vapor Engine," as it is called, on the principle 

 of M. du Tremblay, a French inventor, is now attracting the atten- 

 tion of London mechanics and savans. The engine was originally 

 brought out in Paris, in 1846; subsequently the French government 

 had one constructed, and appointed commissioners to experiment as to 

 its value. The commissioners made a report, in which they stated 

 that the power of the steam-engine was more than doubled by the ad- 

 dition of M. du Tremblay's apparatus, without any additional fuel be- 

 ing required. The invention, it appears, is applied " either to a 

 single engine with two cylinders and pistons, or, as is usual for mari- 

 time purposes, to two distinct engines with a cylinder and piston each." 

 To the engine exhibited a small pipe is attached from a boiler, by which 



