32 ANNUAL OF SCIENTIFIC DISCOVERY. 



propelled during the present season with side screws one at each side, and 

 two short-stroke, high-pressure engines, connected by direct application to the 

 cranks. It has been running in connection with the New York Central 

 Railroad and Lake Erie Railroad, between Buffalo and Sandusky cities, and 

 with astonishing success. She now carries 300 tons more freight, and uses 

 only one-half the fuel that she required with her paddle-wheels and old en- 

 gines. Her cylinders are of 3 feet stroke and 26 inches bore, and her steam- 

 pressure is 45 Ibs. on the square inch. Scientific American. 



Leper's Improvement in Propellers. It is frequently desirable in practice, to 

 drive the screw-propeller at such velocity as would endanger the safety of the 

 engines, and gearing or pitch chains are introduced in order to surmount this 

 difficulty. The propeller Sarah, lately constructed by Captain Loper, of Phil- 

 adelphia, has some arrangements for overcoming this difficulty, of a novel 

 character : The shafts of the engine and of the propeller are placed exactly in 

 line, a fact, by the way, which adds greatly to its convenience, and forms one 

 of the most desirable peculiarities of this machine. To the inner extremity 

 of the propeller-shaft is keyed a crank. The engine-shaft proper is very short, 

 and placed some feet further forward, its after end being provided with a short 

 universal joint. From this universal joint to the extremes of the crank ex- 

 tends a stout shaft, which we will term the gyrating shaft, on account of its 

 peculiar motion, revolving while one end is also compelled to describe a cir- 

 cle. A gear-wheel is keyed on this gyrating shaft, near its after end, and a 

 stout ring of cast-iron, with suitable gear on its interior surface, is fixed in 

 the vessel in such position that the gear-wheel shall always mesh into and 

 travel around within it. The proportion of the parts may be modified so that 

 the propeller shaft shall be compelled to revolve as much faster than the en- 

 gine-shaft as may be desired. The multiple in this steamer is 1\ to 1, so that 

 while the engine makes 100 revolutions the screw-propeller makes 225, and 

 the apparatus is reported by the engineer as producing very little friction, 

 noise, or vibration. 



Palmer's Improvements in Propellers. An improved screw-propeller, in- 

 vented by Mr. Edward Palmer, of Southampton, England, consists of a light 

 skeleton frame, forming two wheels, held together by cross-arms at the re- 

 quired distance, secured by bolts and nuts into suitable grooves, in which 

 the curved blades four in number are fixed. These blades are made of 

 plate-iron, formed to take as much purchase in the water as will have the 

 maximum effect without choaking. One side of each blade is placed at an 

 angle of 65, and the other takes the water at an angle of 45. They are 

 capable of being removed or attached at pleasure, and to suit the power of 

 the engine and sailing of the vessel. When not required as a propeller, this 

 screw may be allowed to revolve by the natural force acquired by drawing 

 through the water, with scarcely any impediment to the vessel's motion, from 

 its lightness and the peculiar angle of the blades, as, when detached from the 

 fast gearing, it revolves on the shaft with the slightest power. The patentee 

 considers that the subject has as yet been but imperfectly understood, and 

 that he has at last discovered the most perfect and effective figure and pitch 

 of the screw-propeller ; and he claims for it a ready inclination to revolve 



