MECHANICS AND USEFUL ARTS. 67 



entire cost of this apparatus is estimated by the inventor at some 

 $1,200 to $1,500 per mile, and he calculates the average saving 

 thereby in the wear of track and rails alone at $350 per mile per 

 annum. 



Gardner's Compound Car Axle. In this new car axle, each wheel 

 is shrunk upon a sleeve which has a loose inside flange upon it and a 

 small rim on the inside of the flange. The axle has a fixed flange upon 

 it, inside of the wheel, and it extends through the sleeves. The 

 sleeves of the wheel, therefore, run upon the axle, and are like long 

 boxes which are secured by screw bolts. By this arrangement of the 

 axle, an independent motion is given to opposite wheels without 

 affecting the relative lateral action. The excessive strain upon the 

 common axle in turning narrow curves is obviated and the danger of 

 breakage removed. 



In turning curves of average radius, and with ordinary trains, a 

 large portion of the motive power may be saved. With the common 

 axle, owing to the greater distance to be traversed over in the same 

 time by the wheel on the outer rail, all the wheels on one rail must 

 slide to compensate for the natural tendency to a difference in veloc- 

 ity. With this axle, each wheel moves with a velocity due to the 

 length of rail to be traversed. 



In the application of the brakes the torsion of the axle is also 

 obviated each wheel turning with the velocity due to the pressure 

 of the brake on itself, and not affecting or being affected by the 

 other. Scientific American. 



Cast-Iron Driving Wheels. Henry A. Chase, of Boston, Mass., 

 has invented an improvement in cast-iron driving wheels for locomo- 

 tives, which consists in casting the " counterbalance " in a double- 

 plated chilled wheel opposite the crank-pin in the inner face of the 

 tread, between the two sides, but not touching them. It is cast on 

 the tread, and stands up from it in the hollow part of the wheel, like a 

 plate, but is not attached to the hub. The plates of the wheel, there- 

 fore, are made of equal thickness throughout, and consequently when 

 cast they contract equally. The counterbalance, or solid plate, cast 

 opposite the crank pin inside of the wheel, is therefore free to con- 

 tract without affecting the side plates after being cast. Scientific 

 American. 



NEW WAY OF CHECKING RAILWAY BAGGAGE. 



The following method of checking baggage has recently been 

 adopted with great satisfaction on two or three of the English rail- 

 ways. 



When a train, say a down train, arrives at any particular station, a 

 porter attends with a book. It contains tickets of stiff card board 

 bound in the book. Each ticket is about 3 inches long and 1 inch 

 wide. It is partly cut. So that two separate parts of it can be easily 

 torn off. The tickets are numbered differently, but each of the three 

 parts of a ticket has the same number. The outer part of the ticket 



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