CHAP. VI. WILLIAM HEDLEY'S EXPERIMENTS. 91 



established method of hauling coal; and pronounced 

 that they would " never answer." 



Notwithstanding, however, the comparative failure oft 

 this second locomotive, Mr. Blackett persevered with) 

 his experiments. He was zealously assisted by Jonathan"/ 

 Foster, the engine-wright, and William Hedley, thel 

 viewer of Wylam Colliery. The latter was a highly in- ; 

 genious person, and proved of great use in carrying out 

 the experiments to a successful issue. One of the chief 

 causes of failure being the rack-rail, the idea occurred 

 to him that it might be possible to secure sufficient 

 adhesion between the wheel and the rail by the mere 

 weight of the engine, and he proceeded to make a series 

 of experiments for the purpose of determining this 

 problem. He had a frame placed on four wheels, and 

 fitted up with windlasses attached by gearing to the 

 several wheels. The frame having been properly 

 weighted, six men were set to work the windlasses ; 

 when it was found that the adhesion of the smootLj 

 wheels on the smooth rails was quite sufficient to enable^ 

 them to propel the machine without slipping. Havingj 

 thus found the proportion which the power bore to the; 

 weight, he demonstrated by successive experiments that 

 the weight of the engine would of itself produce sufficient 

 adhesion to enable it to draw upon a smooth railroad the 

 requisite number of waggons in all kinds of weather. 

 And thus was the fallacy which had heretofore pre vailed ; 

 on this subject completely exploded, and it was satis-i 

 factorily proved that rack-rails, toothed wheels, endless 

 chains, and legs, were alike unnecessary for the efficient 

 traction of loaded waggons upon a moderately level road. 1 



From this time forward considerably less difficulty 

 was experienced in working the coal trains upon the 

 Wylam tramroad. At length the rack-rail was dis-f 



1 Mr. Hedley took out a patent to secure his invention, dated the 13tlA 

 March, 1813. Specification No. 3666. 



