50 Mechanical Philosophy. [Chap. T, 



Verv i^reat improvements have also been made, 

 durin"- the period in question, in the principles and 

 construction of Water-Mills. The proper mode 

 of adjusting forces, and calculating velocities, in 

 this, as well as in almost every other branch of hy- 

 draulics, has long been considered among the most 

 difficult problems in philosophy. — Dr. Desaguliers, 

 early in the century, made a number of experi- 

 ments on mills, and suggested some important im- 

 provements in their principles and construction. 

 About the same time, M. Belidor, of France, 

 Mr. Emerson, of Britain, and J. Bernoulli, em- 

 pIo}^ed their great learning and talents on this sub- 

 ject, and made considerable progress in its illus- 

 tration. These were followed by Mr. Lambert, 

 of Berlin, Mr. Elvius, of Sweden, Professor Karst- 

 ner, of Gottingen, M. de Parcieux, before men- 

 tioned, and Messrs. Smeaton, Barker, and Burns, 

 of Great Britain. To attempt an enumeration in 

 detail of all the inventions, discoveries, and usefld 

 suggestions produced by these several philosophers 

 and artists, would swell this account beyond all 

 bounds. It is sufficient to say, that although that 

 part of the science of hydraulics which relates to 

 mills did not arrive at absolute certainty and per- 

 fection in their hands; yet they made so many 

 .successive additions to the knowledge of preceding 

 theorists, that to each large acknowledgements are 

 due from the friends of human improvement. Nor 

 ought the still later inquiries of Mr. Waring of 

 Philadelphia, on the same subject, to be forgotten. 

 His memoir on the )7iaximum velocity of a wheel 

 or other body, moved by a giveu quantity of iluid, 

 may be regarded as a singular monument of accu- 



