ON HYDRAULICS AS A BRANCH OF ENGINEERING. 17i) 



at a distance from the sides and bottom of the reservoir, pro- 

 mising to investigate with similar accuracy in a future memoir 

 the cases which may occur to the contrary. 



A note is appended to the memoir by M. Lesbros, contain- 

 ing formulae for calculating the effective expenditure of com- 

 plete orifices ; and also a Table of constants, which gives the 

 effective expenditure of each orifice as compared with experi- 

 ment. We have been thus particular in detaihng the results of 

 MM. Lesbros and Poncelet's work, because they have com- 

 prehended all the cases upon which there remained any doubts, 

 and with very few exceptions are in accordance with the expe- 

 riments of Brunacci, Navier, Christian, Gueymard, D'Aubuis- 

 son, and by the author of this paper *. So that in point of 

 accuracy and laborious investigation, the authors of these va- 

 luable accessions to our knowledge, not only merit our grati- 

 tude, but have very amply i-ephed to the liberality of the French 

 Government. 



Having thus endeavoured to elucidate the labours of the 

 foreign philosophers who have contributed so greatly to the 

 progress of hydraulics, it only remains for us to notice the 

 scanty contributions of our countrymen to the science. While 

 France and Germany were rapidly advancing upon the traces 

 of Italy, England remained an inactive spectator of their pro- 

 gress, contented with the splendour of her own Newton, to 

 receive from foreigners whatever was original or valuable in 

 the science. The Philosophical Transactions, rich as they 

 are in other respects, scarcely contain a single paper on this 

 subject founded on any experimental investigations. Some 

 erroneous and inconclusive inferences from Newton, by Dr. 

 Jurin ; a paper on the Measure of Force, by Mr. Eames ; a 

 paper on Wiers, by Mr. Roberts ; another on the Motion and 

 Resistance of Fluids, by Dr. Vince ; and a summary of Bossut 

 and Dubuat's Experiments on the Motions of Fluids through 

 Tubes, by Dr. Thomas Young, comprise nearly the whole of 

 the papers on hydraulics in the Philosophical Transactions. 

 The various treatises on the subject published by Maclaurin, 

 Emerson, Dr. Matthew Young, Desaguliers, Clare and Switzer, 

 with the exception of the theoretical investigations, are compiled 

 principally from the works of foreigners ; and it was not until the 

 subject was taken up by Brindley, Smeaton, Robison, Banks 

 and Dr. Thomas Young, that we were at all aware of our defi- 

 ciency. Practical men were either necessitated to follow the un- 

 certain rules derived from their predecessors, or their own expe- 

 rience and sagacity, for the little knowledge they possessed. 

 * Philosophical Transactions for 18SI, 

 N 2 



