^193 



M>B 



MISCELLANEOiJS lOTKLLiGENCE. 



If (> 



ECHANICAL SciENCE. 



1. On the combined Action of a Current of Art Cthd'ihe Pressure, 

 of the Atmosphere. — The pl^uiomena observed by M. Clement 

 Desormes*, when a flat plate is opposed to air or vapour passing 

 into the attnosphei'e from an aperture in a plane sttrface, liave been 

 rendered so easy of pi-ddviction by M. Hachette, as to be at the 

 command of any person in any situation. M. Hachette has also 

 ^ccQi^i panic d the description of, his instruments jiyith elucidations, 

 experiments, and philpsophical reasonings. , - , 



Tlie first simplification by M, Hachette was to make the nozzle 

 of a pair of double chamber-bellows terminate in the middle of a 

 flat plate ; lie found that when the bellows were worked, effects were 

 produced opposite the jet of air of the kind described by M. 

 Cieonent, disks of card and other substances being; drawn towards 

 the ^erture against the direction of the current. At the same 

 time that lie described this experiment, he also announced his hav- 

 ing produced the same effects by using a stream of water instead 

 of a stream of air. 



The apparatus was still further simplified, so as to make the 

 stream of air from the mouth sufliciqnt to produce the effect. A 



i>»'{|3fcl 





hiM\\Q0U. «<tr iRv 



tin tube, A, Fig, 1, was soldered tothetniddle of a round tin plate, 

 in the centre of which was a small orifice, E ; three or four small 

 projections of the tin, // were left at the edges of the plate, to pre- 

 vent the disks of paper, card, or metal, fi-om slipping o(f sideways. 

 The figure is on a scale of one-half. Instead of the tin plate, a piece 



* See the last volume of Jhis Journal, p. 47S. 

 JULY— OCT, 1827. 



