34 TRANSACTIONS OF THE 



Result. 



Mean weight by first trial, 4,953 lbs. 12 oz. 4-10. 



Mean weight by second trial, 4,954 lbs. oz. 



Mean difference of weight by first and second 



trials, lbs. 3 oz. 6-10. 



Second. — Two trials of Sampson's 100-ton railroad track scale. 



This railroad track scale is 11 9 feet in length and about 5 feet in 

 width. The metal weighed by it was placed upon a railroad car, 

 consisting of two ordinary railroad four-wheel trucks, resting upon 

 railroad rails, placed four feet nine inches apart, which rested upon 

 the track scale. The wheels, or hearing points., of each truck upon 

 this scale were four feet six inches apart, and the distance between 

 the centre of those trucks was eleven feet two inches. 



This track scale of 1 1 9 feet in length was tested at five points or 

 stations, viz : at each of its ends and in the middle, and about mid- 

 way between the middle and the ends of the scale, and numbered 

 successively 1, 2, 3, 4, and 5. Eeginning at one of its ends. The 

 trial of weight was made by placing the centre of this loaded car at 

 each of those five points or stations, which gave the following re- 

 sults, viz : 



First trial. 



The loaded car when placed at ""'"'"J^rdMirnirau wefghf'"^^ 



No. 1 weighed 31,142 lbs. 8 oz. =4 lbs. 8 oz. 



No. 2 " 31,132 lbs. 8 oz. — 5 lbs. 8 oz. 



No. 3 " 31,140 lbs. Ooz. =2 lbs. oz. 



No. 4 " 31,142 lbs. 8 oz. =4 lbs. 8 oz. 



No. 5 " 31,132 lbs. 8 oz. ~5 lbs. 8 oz. 



Sum 5)155,690 



Meanof5wts. 31,138 



Second trial. • 



The loaded car returning at 



Station No, 4 weighed 31,138 lbs. oz. —3 lbs. 10 oz. 



No. 3 " 31,147 lbs. oz. =5 lbs. 6 oz. 



No. 2 " 31,139 lbs. oz. —2 lbs. 10 oz. 



No. 1 " 31,142 lbs. 8 oz. =0 lbs. 14 oz. 



Sum 4)124,566 8 



Mean of 4 weighings, 31,141 10 



