MECHANICS AND USEFUL ARTS. 27 



IMPROVEMENT IN LOCOMOTIVES. 



TUE English engineers are directing attention to the superiority of 

 Crampton's system of building locomotives by suspending on the extrem- 

 ities of the frame. Mr. Crampton places the driving wheels at the 

 end of the engine, instead of the centre, and these wheels carrying about 

 one half of the whole weight of the engine on them, it is clear that one 

 half will be on the driving wheels ; and, by assuming four wheels at 

 the other end to take the other half, the machine, in fact, is suspended 

 on the extremities ; but, in the ordinary machine, the driving wheels 

 being in the centre, with half the weight on them, the other half is 

 necessarily equally distributed on the fore and hind wheels, having the 

 effect of a balance beam action one of the greatest causes of oscilla- 

 tion. To accomplish the same result, the superintending engineers of 

 the Great Western and Northern railways, England, have adopted the 

 plan of applying compensating springs, which have the effect, to a cer- 

 tain extent, of placing the weight of the engine on the extreme ends. 

 Scientific American. 



IMPROVEMENT IN RAILWAY AXLES. 



Ax important improvement, to prevent the heating of railway axles 

 and the bearing parts of machinery, has recently been effected by Mr. 

 George Little, of England. His plan is to bore several longitudinal 

 apertures, for about 15 inches, up each end of the axle, letting the 

 same terminate by several tubes let into the axle under the body of the 

 carriage, so arranged that the centrifugal force will impel a powerful 

 current of cold air through the apertures, thereby keeping the journals 

 and bearings of the axles from heating. To prevent grit, &c., getting 

 into the grease-box, a circular plate is screwed on the end of the axle. 

 This principle is also applicable to the shafts of stationary and marine 

 engines, and, in fact, to all kinds of shafts used in machinery. Min- 



ing Journal. 



RAILROAD CHECK-SIGNAL. 



THE following is a description of a check-signal, invented by Mr. 

 Richard Rollings, of Boston, designed for use when from any cause a 

 signal is needed to inform the engineer that the train must be stopped. 

 A cross-bar made of wood or iron, equal in length to the gauge of the 

 road, is laid across the track, between the rails, and is there secured in 

 place. In the centre of the cross-bar a stout plug or pin is fixed, pro- 

 jecting upward eight or ten inches. Beneath the engine a roller is 

 hung transversely, through the centre of which an iron tongue is 

 fastened, of sufficient length to strike the plug when the engine passes 

 over it. On the upper side of the engine, over the roller, is a spring 

 fastened to the engine frame, consisting of a trigger, a set of wheels 

 acting on a principle similar to that of a clock, and a hammer and bell. 

 The trigger has two arms one extending downward, and connecting 

 with the roller, the other extending upward, and communicating with 

 the wheels. The spring is set by winding up, and is held in place by 

 the trigger. Then, when the engine passes over a cross-bar, the tongue 



