THE CONQUEST OF TIME AND SPACE 



whereby the carriage was made so easy that one horse 

 would draw four or five chaldrons of coal to a load.'' 



At this time the use of iron rails had not been thought 

 of, or at least had not been tried, probably from the 

 fact that iron was then very expensive. Even the 

 wooden rails in use, and the wheels that ran upon 

 them, were of no fixed pattern. Some of these rails 

 were in the form of depressed grooves into which an 

 ordinary wheel fitted. But these were very unsatis- 

 factory because they became filled so easily with dirt 

 and other obstructions, and a more common type was 

 a rail raised a few inches above the ground like a mold- 

 ing, a grooved wheel running on the surface. 



Such rails were short lived, splitting and wearing 

 away quickly, and being easily injured by other ve- 

 hicles. But they were, on the whole, more satisfactory 

 than the depressed rails, and were the type adopted 

 when iron rails first came into use, about 1767. Ten 

 years later the idea of the single flange was conceived, 

 not placed on the wheels of the cars as at present, but 

 cast on the rails themselves. These flanges were first 

 made on the outside of the rails, and later placed on 

 the inside, the wheels of the cars used on such rails 

 being of the ordinary pattern with flat tires. 



But, in 1789, William Jessop, of Leicestershire, be- 

 gan building cars with wheels having single flanges on 

 the inside like modem car wheels, to run upon an ele- 

 vated molding-shaped iron rail; and the many points 

 of superiority of this type of wheel soon led to its gen- 

 eral adoption. So that aside from some minor changes, 

 the type of rails and wheels in use at the close of the 



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