MECHANICS AND USEFUL ARTS. 15 



radial paddle-wheels for sea-going vessels, B. F. Isherwood, Chief 

 Engineer of the United States Navy, concludes that, " for vessels of a 

 medium size and a nine days' voyage, the perpendicular paddle-wheel 

 possesses decided advantages over the radial paddle-wheel, economi- 

 cally, potentially, and in view of the practical advantages of less strain 

 upon the machinery and ship." The correctness of this conclusion 

 has, however, been disputed by others, in later numbers of the same 

 journal. 



ENGINE FOR STREET LOCOMOTION. 



THERE is now in operation upon the Hudson River Railroad, for 

 drawing the cars through the city, a double condensing engine, so con- 

 structed as to make no noise and emit no smoke. On the outside it 

 resembles a baggage-car, all the works being inside. It has two cyl- 

 inders of twelve-inch diameter and eighteen-inch stroke. It condenses 

 its steam, but can be immediately converted into a non-condensing 

 high-pressure engine, if required. It carries a tank of water suffi- 

 ciently large for the trip from Thirty-first Street to Chamber Street, 

 and, of course, there is no puffing. It burns coke and uses a blower, 

 so that no smoke, sparks, or chimney are visible. It works quietly, 

 and has thus far proved itself capable of drawing a train of eight cars 

 with the utmost ease, at the cost of only a few cents per trip for fuel. 

 Scientific American, Aug. 3. 



OSCILLATION LOCOMOTIVE ENGINES. 



AT the meeting of the Society of Arts, on Jan. 30, Mr. George 

 Heaton read a paper, " On the cause of the oscillating motion in loco- 

 motive engines at high velocities, and a method of correcting it." 

 When a man walks upright, on placing his right foot forward he 

 throws his right hand in the same direction, and his left arm back- 

 wards, and when the left foot is advanced the left arm follows its di- 

 rection and the right goes back. This counteracting motion, which 

 comes instinctively, keeps the body upright, and the author has en- 

 deavoured to apply this principle to prevent transverse oscillation in 

 locomotives, from the effects of which they are frequently thrown off 

 the track. He illustrated his remarks by a working model, which 

 was driven at a velocity of forty-two miles per hour, and the oscilla- 

 tion, evidently taking place from the unequal concussion of the pis- 

 tons at the dead parts of the stroke, was so great as to cause the 

 frame-work to vibrate transversely some two or three inches from its 

 position at each end alternately, as if turning backwards and forwards 

 on a central pivot. Experiments were then shown with the wheels 

 weighted on one side to balance the force of the crank-motion, which 

 had some effect Dt a moderate speed, but did not cure the oscillation 

 at the highest velocity. It will be found when an engine of twenty- 

 inch stroke, with six-feet driving-wheels, goes fifteen strokes per min- 

 ute, or three miles per hour, it requires one tenth of the weight mov- 

 ing along the horizontal line (that is, the piston and gearing moving 



