WATER BLOWING MACHINE, 5$ 



To judge of this in the cafe before us, we fitted in one 

 of thele crofles, all the other circumftances remaining as above, 

 and then obferved the progrefs of the inftrument. 



The column of water in the tube frequently defcended toThey diminifh 

 24 inches, and feldom rofe to 26 : whence we may eftimate tlle *■&&* 

 the mean height, which before was 26 inches, only 2 4-J. 



Now this difference occafions a diminution of velocity in 

 the em\ix of the air, and confequently (hews the faultinefs of 

 this method" under the circumftances here mentioned. 



IV. Experiments on the Effect of Hatches placed near the Orifice 

 of the Machine. 



The hatch a Fig. 1. was replaced in the grooves adapted Advantage ^f 

 to the channel. We altered its height from the bottom of the \ n f{ ux if water, 

 channel, obferving the movements of the anemometer, in 

 order to find the pofition moft favourable for the effect of the 

 machine. 



The mean height of the column of water in the tube never 

 exceeded 28 inches, the elevation of the lower part of the 

 hatch above the bottom of the channel, being then five inches 

 one line; and it is remarkable, that the difference of a tingle 

 line in this elevation lowered the water in the tube confider- 

 ably. 



V. Experiments on the Crojfes when the Hatch is ufed. 



The hatch being placed as has juft been faid, we, fitted the When thus re* 

 crofs again at the fuperior aperture of the funnel, when the 8 ed * 

 water in the tube of the anemometer funk. We then varied 

 the height of the hatch above the bottom of the channel, 

 obferving the progrefs of the inftrument, to determine the 

 moft advantageous pofition for it under the prefent circum- 

 ftances. 



The elevation of five inches eight lines was now found The crofs pro* 

 the moft favourable to the effea. With this the water ofcil- duced more air > 

 lated in the tube between 28 and 30 inches, moft frequently 

 reaching the latter height, which we could never bring it to 

 exceed, whatever changes we made in the arrangement of 

 the parts that compofe the machine. 



If we compare the fituatton of the hatch before the addition *>«* expended 

 of the crofs, with that which is moft fuitable in the ca/e™ ewate * 

 before us, we find an increafe of feven lines in the height > • 



2 from 



