Manchester Memoirs, Vol. xlvi. (1902), No. 10. 27 



Helmholtz states that " the total quantity of all the 

 forces capable of work in the whole universe remains 

 eternal and unchanged throughout all their changes." 

 Tyndall also, in his Heat as a Mode of Motion, says, 

 p. 141, "To create or annihilate energy is as impossible 

 as to create or annihilate matter, and all the phenomena 

 of the material univ^erse consist in transformations of 

 energy alone." 



Newton attempted to disprove the Cartesian doctrine 

 of the conservation of motion, by showing that force was 

 lost by letting two equal pendulums of lead or soft clay 

 fall against each other. This demonstration, would not, 

 however, be accepted at the present time, as the energy in 

 this instance was transformed into ths motion of heat. 

 Molecular mechanics were unknown to Newton, and also 

 to his followers for more than a century after the publica- 

 tion of the Principia. 



That the quantity of motion and rest in the universe is 

 not always the same now admits of an easy demonstration. 

 Let it be granted that at any given moment the universe 

 contains a definite amount of rest and motion, or, in other 

 words, that all the static and dynamic forces in the 

 universe are /// cqiiilibrio. Now, it will be evident that the 

 explosion of our disc of gunpowder (4-5 lbs.) would add 

 2200 foot-tons of energy and motion to the sum pre- 

 viously existing. Moreover, if all the endothermic bodies 

 on the planet were exploded at the same moment, the 

 sum of their motions and energies would further increase 

 the sum of the motions and energy of the universe. 



Just as the molar and molecular j-/'c?//ic forces of bodies 

 are identical with the state or force of rest, so also is the 

 attribute or force of m&tion identical with the molar and 

 molecular dynamic forces of these same bodies. It is 

 therefore evident that, as a body cannot be at rest and in 



