ON THE HISTORV OF HrDRAULrCS AND PNEUMATICS. 361 



About the same time, the profound Leonard Euler applied himself, with 

 some success, to the examination of the motions of fluids, particularly as 

 they are connected with the subjects of seamanship and naval architecture; 

 but the investigations of Euler are in general more remarkable for raathe- 

 inatical address, than for philosophical accuracy and practical application; 

 although his calculation of the resistance of the air to the motions of pro- 

 jectiles may be employed with considerable advantage by the gunner. 



The beginning of the modern experimental improvements in hydraulics 

 may perhaps be dated from the investigations of Smeaton respecting the 

 effects of wind and water, which were published in the Philosophical Trans- 

 actions for 1759. His observations are of material importance, as far as they 

 are capable of immediate application to practice, but he has done little to il- 

 lustrate their connexion with the general principles of mechanics. It was 

 JVIr, Borda that first derived from a just theory, about 10 years after, the 

 same results, respecting the effects of undershot water wheels, as Smeatoil 

 had obtained from his experiments. Before this time, the best essay on the 

 subject of water wheels was that of Elvius, published in 1742; his calcula- 

 tions are accurate and extensive; but they are founded, in great measure, 

 on the imperfect suppositions respecting the impulse of a stream of water, 

 which were then generally adopted. 



Our countryman Mr. "Watt obtained, in 17^9, a patent for his improre- 

 ments of the steam engine, which includes almost every essential change 

 that has been made since the time of Beighton. On a subject so important, 

 it cannot be superfluous to insert the words of the inventor, whose admiraWc 

 application of the sciences, to practical purposes, most justly entitles him to 

 a rank among philosophical mechanics, not inferior to that of Ctesibius a!i»d 

 Dr. Hooke. 



** My method of lessening the consumption of steam, and consequently 

 fuel, in fire engines," says Mr. Watt, in his specification of his patent, " con- 

 sists of the following principles. First, that vessel in which the powers of 

 steam are to be employed, to work the engine, which is called the cylinder 

 in common fire engines, and which I call the steam vessel, must, during 

 the whole time the engine is at work, be kept as hot as the steam that 



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