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TRANSACTIONS OF THE 



there be no springs; and if there be springs intervening between 

 the engine and the driving wheels, the oblique direction of the 

 connecting rods, through which the power is applied, will pitch 

 and rock the suspended parts. This dilemma, Scott Kussell 

 states, was met by the steam carriage men, by tying down, and 

 thickening and stiffening the springs until they become little 

 better than rigid blocks of metal. Gm-ry left his engines entirely 

 unsuspended in one of his latest carriages. Russell himself suspen- 

 ded his engines and boiler on springs so still tliat he had to put 

 on extra springs to bear his carriage body, in which the passen- 

 gers rode; and tliis plan was adopted by Hills, one of the latest 

 inventors. Hancock, Church and others, used a parallel connec- 

 tion, consisting of a geai-ing chain to transmit the power from the 

 engine crank shaft to tlie driving wheels; this completely avoided 

 the pitching caused by the engine when the connection was 

 oblique, but the pitching and jolting caused by the unevenness 

 of the road soon broke the chain, if the springs had much action; 

 and practically, this theoretically perfect device would not allow 

 more than half springs, three feet long, whose play could not 

 have exceeded eight-tenths of an inch without straining them. 



The effect of the irregular motion caused by the road may be 

 judged of by the experiments of Morin, who found that, at nine 

 miles per hour, a carriage with its springs blocked required 

 twice the power that drew it when the springs were in action; 

 and that the enormous difference increased with the increase of 

 speed. Estimating from the results of Morin's experiments, I 

 conclude that at a speed of 23 miles per hour on a McAdam road, 

 a carriage with half elliptic springs three feet long, would require 

 three times more power than one with elliptic springs six feet 

 long, the bores being of equal thickness. 



The power lost by irregular motions is equal to what would 

 be requii-ed to shake the mass to the same extent when it is not 

 moving forward. Let any one jump like a cart on a rough road, 

 or shake himself like an unbalanced locomotive, and he will 

 soon be fatigued. Let him then consider that some locomo- 

 tives have actually expended in this way at least twelve hun- 

 dred times more power than he can exert, and he will have a 

 general notion of the loss of power resulting from the deviations 

 from the proper line of motion. 



In 1847, or tliereabouts, Robert Stephenson took out a patent 

 for an arrangement to prevent sinuous motion and rocking. It 

 consisted in the use of three cylinders, one acting on a crank in 



