Manchester Memoirs, Vol. xlvi. (1902), No. 10. 19 



In this review, the author, while expressing his high 

 opinion of Ewart's scientific attainments and labours, 

 manifests his inability to do justice to the subject of 

 which he had been requested to give an account. He 

 confuses the moving force of bodies under the free action 

 of gravity with that of connected bodies, as in the work 

 done by machines ; echoes the opinions of those who 

 maintained that the dispute was only about terms, and 

 characterises as assumptions the clear demonstrations of 

 Smeator, Wollaston and Evvart of the loss of moving 

 force in the collision of inelastic bodies, which is now 

 common knowledge. 



The greater number of experiments on the measure 

 of moving force, as will be seen, were made with recti- 

 linear motions, until Smeaton found, in the course 

 of his engineering undertakings, the great difference 

 between accepted theory and actual practice, and under- 

 took a series of experiments on the rotatory motions of 

 bodies which confirmed, in the most complete manner, 

 the results previously obtained with rectilinear motions.* 



Although the proportion of moving force necessary 

 for giving different velocities to bodies rotating about an 

 axis was completely demonstrated by Smeaton, yet, the 

 design of his experimental machine, which involved the 

 motion of several of its parts in addition to the falling 

 weights used therewith, failed to satisfy the critical 

 accuracy of Atwood and other opponents of the vis viva, 

 who made the most of the small differences between the 

 theoretical results and those obtained from Smeaton's 

 experiments. Now, the gyroscope, from the fewness and 

 simplicity of its parts, affords the means of determining 

 the moving force of a body in a decisive manner, as the 



*Phil. Trans., Vol. LXVL, 1776. Abridgment, Vol. 14, p. 72. 



