376 JAMES WATT. 



occasioned the Reasons of Moving Forces to be disin- 

 terred from their dusty shelves. Without hesitation they 

 pulled down their former idol ; the Marquis of Worcester 

 was sacrificed to the desire of annulling the claims of 

 Solomon de Caus ; the bomb placed on a burning brazier 

 with its ascending tube, ceased at last to be the true germ 

 of the present steam-engine ! * 



As to myself, I do not grant that the man was of no 

 utility who, reflecting on the enormous elasticity of steam 

 when greatly heated, was the first to perceive that it 

 might be used to raise great quantities of water to all 

 imaginable heights. I cannot admit that no mention is 

 due of the engineer who was also the first to describe a 

 machine adapted to realizing such effects. Let us not 

 forget that we cannot judge soundly of the merit of an 

 invention, without transferring ourselves in imagination 

 to the epoch in which it was made ; without expelling 

 from our mind for the time all the knowledge that subse- 

 quent centuries have poured in upon us. Let us imagine 

 an ancient mechanic, Archimedes, for example, consulted 

 on the means of raising the water contained in a vast, 

 closed, metallic recipient, to a great height. He would 

 certainly speak of great levers, of single or multiplied 

 pulleys, of a windlass, perhaps of his ingenious screw ; 

 but what would be his surprise if to solve the problem 

 some one would be content with a fagot and a match ? 



* In Les Raisons des Forces Mouvantes, it is evident that De Caus 

 ascribes the force which shivered the shell entirely to the air; and he 

 seems to consider that the force of the air proceeded from the water 

 which exhaled in it. M. Arago cannot be borne out in saying, of those 

 who do not arrive at his conclusions, that " d'ecarter tout nom Fran- 

 gais" was their principal thought. We know not to whom he alludes 

 in assigning such a base motive, but the assertion infringes greatly on 

 the impartiality which he promised us. Translator. 



