166 Wisconsin Academy of Sciences^ Arts, and Letters. 



As the weight on each wheel and the momentum with which 

 the wheels strike irregularities in the track affect the " wear 

 and tear," we give the following data for the two gauges : 



WEIGHT ON WHEELS — THEIR MOMENTUM. 

 [Passenger trains— Speed 25 miles per hour.] 



The ends of the rails are beaten to pieces, the surface abrad- 

 ed, the ties splintered, the fibre of the wood cut under the iron, 

 weak joints rapidly made worse, so that each succeediog wheel 

 falls with an increasing force upon the ends of the yielding 

 rails by the tremendous forces developed by the passage of these 

 enormous weights at high speed. The lightest broad-gauge 

 coach weighs about 16 tons, or 32,000 lbs. empty, and ham- 

 mers the rail joints with 4,000 lbs. on each wheel. When 

 loaded and driven over the rails at 25 or 30 miles per hour, 

 the weight of the blow is enormous and terribly destructive to 

 the superstructure, crushing out the best rail in five or six 

 years. The passenger car of a three-feet gauge would only 

 hammer the rail with 1,500 lbs. per wheel. The same applies 

 to locomotives. A 30-ton locomotive, and its loaded tender, 

 weighing about 14 tons, or a total of 57 tons, will exert a pres- 

 sure of nearly six tons on each driving wheel. When driven 

 at a high speed, the strain upon the track is terribly destruct- 

 ive. The " Fairlie " engine, constructed for narrow-gauge lines, 

 bears its whole load, including wood and water, on the driving 



