STREMMATOGRAPH. • 99 



to the rail were very firm in the ballast, and to the eye did not 

 seem to depress as much as those on either side ; therefore, the 

 compression stresses should be higher than on ties all practically 

 depressing alike in the ballast. 



It will be exceedingly interesting and important to have the 

 records of stresses under this type of locomotive when drawing 

 one of the trains of fifty-five 6o,oc*D-lbs. capacity cars, each 

 carrying i,ooo bushels of grain. 



The picture on the screen shows two trains side by side of 

 fifty cars each, the length of one train not quite reaching from 

 New York to Chicago, but each is 2,000 feet long, and 2,640 

 such trains would fill one continuous track between the two 

 cities.. [See Plate XIII.] 



In the trials of a number of switching locomotives in the yard, 

 on tracks of not very uniform tie spacing, the locomotives having 

 three pairs of coupled drivers, but without pony truck the front 

 driver usually shows greatest tension on the 6 5 -lb rails. 



Under locomotive No. i, at Grand Central Station, having 

 125,000 lbs. upon drivers, the instrument between ties of 30- 

 inch centres, having tie plates, the apparent mean stresses were 

 as follows ; on 65- and lOO-lb, rails respectively : 



65-lb. rail. 



Compression in front of driver, 3j07i lbs. 



Tension under front driver, 51, 964 ' ' 



Compression between front and middle driver, 2,124 ' ' 



Tension under middle driver, 22,445 '' 



Compression between middle and rear driver, 2,362 '' 

 Tension under rear driver, 23,856 '' 



The 65-lb. rails are of recent composition, the elastic limits 

 of the steel being 60,000 lbs., while on the lOO-lb. rails it is 

 65,000 lbs. 



In the above table it is interesting to note the great reduction 

 and more uniform fibre stressses in the lOO-lb. rails as compared 

 with those in the 65-lb. rails. The 65-lb. rails require from six 

 to eight times as much labor to keep them in surface as the 

 lOO-lb. rails in the Grand Central Yard. 



loo-lb. 



rail. 



I, 



181 



lbs. 



8 



-031 







2 



834 







6 



849 







2 



834 







6 



,142 







