MECHANICS AND USEFUL ARTS. O 



wheel, so that the steam cannot escape without driving them. In its 

 passage out from under the cap the steam may be conveyed to a second 

 engine, and applied a second time. The wheels are kept in their 

 place by perpendicular and horizontal set-screws, and by stationary 

 guides. The engine at Tyrees Spring has steam wheels of 10 inches 

 diameter from pitch circle, and 10 inches face ; it has 10 cogs to each 

 wheel, and the position they occupy is such as to give 20 square 

 inches of effective surface. The boiler is a cylinder 20 feet long, 32 

 inches in diameter, carries steam at a pressure of 65lbs. per inch, and, 

 with what fuel the mill makes (dust and slabs), cuts an average of 

 3,000 feet of oak lumber per day of twelve hours. What Mr. Delano 

 saw induced him to put up a similar engine, to drive a single saw, in 

 the mills under his charge. It is of the same size as that at Tyrees 

 Spring, but the boiler is 22 feet long, 36 inches in diameter, has two 

 11-inch flues, and a pressure of steam of 601bs. per inch. With saw- 

 dust and half a cord of green slabs, 5,000 feet of inch-square edge 

 lumber is sawed per day. It has been in operation three months, and 

 it has not been necessary to clean the boiler out once. The only wear 

 observable is in the Babbitt metal, and the arrangement for moving 

 and adjusting the pillow-blocks is such that it is done while the engine 

 is in operation. 



IMPROVED OSCILLATING ENGINE. 



MR. JAMES WYLIE, of New York, has in operation an improved 

 oscillating engine. It is of 6-inch bore in the cylinder, and 12-inch 

 stroke. It employs no valve-rod, and, strictly speaking, the only valve 

 about it is the throttle-valve. The cylinder is horizontal, vibrating on 

 trunnions, and on its top is a spherical projection, smoothly planed on 

 the face, hollow, and it has two openings into the steam passages, 

 leading into both ends behind the piston. The steam-box has three 

 openings, two for the exhaust, and one for the steam. This box is 

 fixed and is concave on the under side to fit like a cap on the central 

 spherical projection of the cylinder. When the cylinder vibrates, it 

 opens communication with the exhaust and steam passages alternately, 

 thus dispensing with the use of the slide-valve. It is a good improve- 

 ment, as it has fewer parts than the common engine, and avoids all 

 loss by back pressure on the valves. Scientific American, Aug. 3. 



DOUBLE-PISTON STEAM-ENGINE. 



IN this machine of M. Paltrineri's, the steam-cylinder has two pis- 

 tons, which move in opposite directions ; a single valve-box suffices to 

 lead the steam at one time to the middle of the cylinder, when the 

 pistons are to be driven outwards, at another to the ends, when they 

 are to be driven inwards. The author points out various applications 

 of this system for locomotives, and for steamships of great power, and 

 he has succeeded in some of them in making very simple arrange- 

 ments, which allow the reduction of the dimensions- and weight of the 

 apparatus. Recudl de la Societe Poly technique. 



