212 ON DIVERGING STREAMS 



was \i inches above the seat, by gradations of 

 l-32nd of an inch each, and the heights of 

 the mercury in the tubes were noted at each 

 step, distinguishing by a P, or a V, whether they 

 shewed pressure from below, or a partial vacuum, 

 and thus a table of five columns was formed. 

 The first column shewed the height of the valve 

 above the seat, and the other four columns, the 

 heights of the mercury in the four tubes, and 

 whether they indicated pressure or vacuum. 



This table shewed, that the pressure from the 

 stream below, on No. 1 tube, continued at H 

 inches of mercury, until the valve was raised 

 from its seat to 1-1 6th of an inch above it; but 

 from that elevation until it was raised to I i inches 

 from the seat, the mercury shewed a gradually 

 diminishing pressure, and at that height the 

 pressure was only 6-lOths of an inch. 



No. 2 tube, shewed its greatest degree oi vacuum, 

 which was one and 8-lOths inches of mercury, 

 when the valve was raised 3-32nds of an inch; 

 from which point, as the valve was further ele- 

 vated, the vacuum became less, until at a height 

 of 3-8ths there was no vacuum, — the mercury in 

 the two Umbs of the tube being at the same level. 

 On raising the valve from 3-8ths to IJ inches, 

 this tube shewed an increasing pressure from the 



