VJO New Hydraulic Machines, [MarcW^ 



jBndIng itself all on a sudden stopped by the pla^'* at the topy 

 produces the ordinary blow of the hydraulic ram. The living 

 force is in part destroyed by the shock, and the rest of it passes 

 in a jet of water which corresponds to the small opening in the 

 plate, and this jet is forced to a great height. This effect, which 

 is common to the machine of Montgolfier, and of M. Mannoury, 

 does not prevent the two machines from differing essentially 

 from each other. Montgolfier's machine cannot dispense with 

 its valves, wliich are essential to it ; while the oscillating column 

 of M. Mannoury has no valve whatever, and preserves the 

 fundamental property of all the machines which he has submitted 

 to the judgment of the Class. By the combination of so many 

 methods, either little known or altogether unknown, in the 

 construction of his hydraulic machines, M. Mannoury has 

 deviated from the ordinary circle of ideas, according to which 

 such machines are conceived ; of course it was likely that he 

 should arrive at results quite unexpected. The author unites the 

 knowledge acquired by study with that fineness of tact which 

 produces inventions. It is therefore to be presumed, that in his 

 hands several of his machines, which at present are merely 

 curious, will acquire a perfection which will make them still 

 more interesting on account of their utility. 



The intermitting syphon, and tiie hydreole, give already very 

 good results, as far as they can be judged of; but new experi- 

 ments are wanting to measure exactly their products. 



We shall defer till another time the particular report which we 

 propose to make of the corn-mill invented by M. Mannoury. 

 We shall only say that this new mill seems to be of more public 

 utility than any other. There are already 14 established at the 

 forges of Paimpont in Britanny, and the departments of the 

 Orne, of the Manche, •M^^\ of Calvados. It consists in a happy 

 application of the machine a reaction, contrived by M. Segner, of 

 the Academy of Berlin, and afterwards subjected to calculation 

 by several illustrious mathematicians, particularly by the two 

 Eulers, father and son, and by M. Bossut. According to very 

 accurate and well authenticated experiments, these mills produce 

 an effect superior to the best executed ordinary mills. 



The commissioners are of opinion that M. Mannoury has 

 rendered essential service to the theory, as well as the practice, 

 of the motion of water, by his researciies and his experiments 5 

 and that his inventions deserve the approbation of the Class. 

 (Signed) Dk PaoNY, Perier, Carnot, Reporter. 



The Class approves the Report, and adopts the conclusions 

 contained in it. 



Certified as conformable with the original, 



The Perpetual Secretary^ Chevalier de VEmpiref 

 (Signed) Delamjbb?;. 



