MECHANICS AND USEFUL ARTS. 43 







Mr. W. Fairbairn showed a specimen of the india-rubber lining from an 

 axle-box that had run 17,000 miles in a locomotive engine; also, a model of 

 the axle-box fitted up with india-rubber, and a specimen of one of the con- 

 necting-rod ends. He stated that it was requisite to take great care to keep 

 oil away from the india-rubber: as in one trial, the india-rubber had lasted 

 only a month, from neglect of this precaution; but, when properly protected 

 from oil, its durability was found to be very great. A cap was now fixed 

 over the india-rubber, as a more complete protection for this purpose. These 

 axle-boxes and connecting-rods were working in several locomotives on the 

 Chester and Birkinhead Railway, and they were found to be now as good 

 and perfect as when first put in, though some had run as much as 17,000 

 miles; they were considered quite satisfactory, and the result of the axle- 

 boxes was an improvement in reducing the wear of the wheel-flanges. 

 The connecting-rods were screwed up at the ends, insteacUof being cottered, 

 as in the usual manner; and this mode of construction he considered an 

 improvement as regarded convenience and security from accident. New- 

 ton's Journal, Feb. 18-39; Jour. Franklin Institute, April 18-39. 



LOUGHRIDGE PATENT BRAKE. 



The construction of this new railway brake is described by the Scientific 

 American as follows : Alongside the throttle-lever there is a bent lever 

 which communicates with a ten-inch friction -wheel, and presses it against 

 the flange of the rear driver, at will. This causes it (the friction-wheel) and 

 its shaft to revolve, and a chain attached to the brakes throughout the train 

 is wound on the shaft. On the shaft is a ratchet-wheel with a pawl, so that 

 as the chain is wound to any given strain, it is kept in place. In connec- 

 tion with it is a weighing-beam, by means of which the power may be grad- 

 uated on the brakes to suit the condition of the rails. A weight sliding on 

 the notched weighing-beam gives more or less power as it is slipped from or 

 to the fulcrum, and, once gauged, the engineer cannot put more power on the 

 brakes if he wished, or should not wish, to; but he can apply any degree 

 less than the fixed maximum down to zero. The beam is fixed so that the 

 engineer cannot slip the wheels, nor break the chain, but can get what power 

 he wishes up to the slipping-point. And this is all that is requisite; for if 

 the wheels ai-e slipped, the retarding power is lessened rather than increased. 

 To loose brakes, a small lever is pulled, and the pawl being thrown out of 

 the ratchet, the chain is suffered to unwind. The great beauty of the con- 

 trivance is the weighing-beam ; for if the power were not gauged, the engi- 

 neer, by braking up too suddenly, would snap any chain that might be 

 used. To relieve the enormous shock which comes upon the pawl as it is 

 thrown into the ratchet, the inventor has attached to its end a long gun 

 spring, which effectually absorbs the sudden strain. The lever once thrown 

 back, the ratchet and pawl below hold the brakes in place, so that the engi- 

 neer need only put on the required power, and may then give his attention 

 to the working of his engine. Coming to a station, the speed of the train 

 may be so controlled that the reverse gear need never be used. The cost of 

 applying the brake to an engine is $75; to an ordinary car, but $30. 



ON BOILER-PLATE JOINTS. 



In the discussion of boiler-plate joints, Mr. Clark demonstrates that the 

 bursting strain on the longitudinal seams of cylindrical boilers is double the 



