250 Mr. Ewart on the Phcenomena aitetiding 



lowing was one. A (fig. 3.) represents a transverse section of 

 a cylindrical horizontal pipe, seven inches in diameter, which 

 conducts air from a blowing apparatus to a furnace. B is an 

 inverted glass syphon inserted into the side of the pipe A. 

 A round hole, 4-lOths of an inch diameter, was made in the op- 

 posite side of the pipe, to which was adapted a conical tube 

 of tinned iron CD, 5*4 



inches long, and whose 



Fig. 3. 



internal diameter was 

 •4- inch at C, and 1"05 

 inch at the extreme end 

 D, which was open to the 

 atmosphere. To the lower 

 side of this conical tube, 

 two perpendicular glass 

 tubes, E and F, were at- 

 tached, their upper ends 

 opening into CD, and 

 their lower ends being 

 immersed in a trough of 



mercury. The centre of the tube E was '5 inch from 

 the inside of the pipe A, and the centre of F was 2*2 inches 

 from the centre of E. Some mercury having been put into 

 the inverted syphon, and the blowing apparatus being set to 

 work (the air passing through A at the velocity of forty-five 

 feet per second), the mercury stood at 1'8 inch higher in the 

 outer than in the inner leg of the syphon ; while the mercury 

 in the trough rose 2-7 inches in the tube E, and only '4; inch 

 in F ; showing a greatly diminished pressure in the air at E, 

 whUe its pressure was much increased in passing from E to 

 F. On the internal pressure in A being increased, the mer- 

 cury rose higher in nearly the same proportion in E and F, 



In the Annales de Chimie et de Physique for September 1827, 

 there is an account of a fact observed in 1826 by Mr. Griffith, 

 engineer, at Fourchambaut, w-hich is described as consisting 

 of this : — That if air strongly compressed in a reservoir escape 

 by an orifice in a plane surface, and if a plate or disk of me- 

 tal be presented to the jet of air, that plate is attracted to, in- 

 stead of being repelled from, the flat surface from which the 

 air issues *. 



In the same article in the Annales de Chimie, there is an 

 account of some experiments and their results on the issuing 

 of compressed steam. 



• This fact had been previously observed in October 1824, by Mr. Ro- 

 berts, a member of the Manchester Philosophical Society. 



Some 



