MEMOIR OF DANIEL TREADWELL. 



505 



The cars upon wliicli the loads were placed were of the common form and size, the bodies resting 

 npon springs. Tlie ^vhecls were 3 feet in diameter and the journals (gudgeons) IJ inches in diametca'. 



With this account of the apparatus, I shall proceed to give an account of six experiments made with 

 the engines before described. 



1. Frida}', October 14, 1836. Experiment made with the Mercurj', with the sparker on the engine, 

 from the depot in Boston to Framingliam, 20 J miles. 



Load or Train. 



Tender No. 4, to which the dynamometer was attached from the first car. 



10 cars loaded with iron nails Weight, 81,843 lb. 



1 car loaded with stone 9,210 



1 car loaded with some iron, and carrying apparatus and four persons 5,050 



Whole weight, 90,103 lb. 



One car was left at the ascent between the 11 th and 12th mile, and is therefore accounted at 

 half its weight carried through. On the return the weight of the car is deducted, which leaves 

 the load on the return 91,795 lb. 



Wood used, being pine of ordinary quality. Out, 83 cubic feet, measured as ordinarily piled. Return, 60 

 cubic feet. The wood required to get up the steam not included in either case, either in tliis or the experiments 

 afterwards made. 



Water used. Out, 5.3.4 cubic feet. Return, 42.5 cubic feet. 



Wood used to evaporate 1 cubic foot of water. Out, 1.55 cubic feet. Return, 1.41 cubic feet. 



The method pursued in noting the velocity and force of the draft, or traction, was as follows. An 

 assistant marked at every thirty seconds tlic |)hico of the index of the dynamometer. 'I'iio time of pass- 

 ing each mile-post was observed and set down bj' myself. Tliese accounts were afterwards compared 

 together, and the mean force of the draft, as shown by the assistant's minutes, cast for each mile. The 



