(Jn tht laUral Communieation of Motion in Fluids. 425 



Experiment XXI. The orifice R, fig. 8, was circular, and 4,5 lines in diameter; the 

 charge was 3 1,7 Inches, and the jet declined a little from the perpendicular. The orifice 

 being through a thin plate, afforded a cubical foot of water in 161". With an additional 

 cylindrical tube of the fame diameter, and ten lines in length, the cubical foot of water 

 was emitted in 121". 



Under a charge of 56 inches, the fame orifice afForded, through the vertical jet, a cu- 

 bical foot in 123" through the thin plate, and in 91'' with the fame additional tube. 



Thefe two refults being combined, give for the expenditure of vertical jets a mean ratio,- 

 between the thin plate and the cylindrical adjutage, of 100 to 134, which is alfo the ratio- 

 between the horizontal jets. 



Experiment XXII. I applied the glafs tube QJl T, fig. 6, to the point S fig. 5. of the 

 compound tube A C M N, the diftance B S being 24 lines. In this fituation the fluid T no- 

 longer rifes in the tube. This proves that the lateral tranflation of jhe fluid in the cylin- 

 drical tube is made very near the place where the vein is contrafted, and that confequent- 

 ly D R muft briflcly flrlke the fide G M. 



By this experiment we fee that the diftance BR to which the oblique filaments ftrikc 

 the fides of the tube, does not amount to 24 lines. Suppofing D O = 20 lines, the time 

 which the particle D employs to pafs through the fpace D O in my experiments is lefs than 

 c",Oi. Let us decompofe the curve-lined motion DR according to the lines DO, OR. 

 Let us fuppofe the acceleration through O R to be uniform, and it will be found that this 

 acceleration is at leaft five times as great as that of heavy bodies. If the lateral force through 

 G R were fimply the mutual attraction of the particles of the water, this attraction in the 

 particle D muft not only overcome the inertia of the particle itfelf, but likewife that of the 

 other particles nearer the axis, which follow D in its deviation through D R, and imprefs 

 upon them a much greater fum of acceleration than that of gravity. Now the force of 

 attraction of one particle of water is not greater than the natural gravity of a thread of wa- 

 ter of the length of one line at moft. The lateral communication of motion, which is the 

 caufe of the acceleration through O R, is therefore much greater than could have been 

 produced by the mutual attra£tIon of the particles of water. 



Propejition VII. By means of proper adjutages applied to a given cyllndric tube, it Is 

 pofllble toincreafe the expenditure of water through that tube in the proportion of 24 to- 

 10, the charge or height of the refervoir remaining the fame. 

 _ I (hall here give an account of the different precautions neceflary to be taken when the 

 expenditure of water through a cylindrical tube of a given. length is requiredto be the 

 greateft poffible. 



i.The inner extremity of the tube AD (fig. 13.) muft befitted at A B with a conical piece 

 of the form of the contra<3;ed vein* ; this incrcafes the expenditure as 12,1 to 10. Every 

 other form will afford lefs. If the diameter at A be too great, the contraction will be; 

 made beyond B, and the feCtion of the vein will be fmallcr than the feCtion of the tube. 



2. At the other extremity of the pipe B C apply a truncated conical tube C D, of which 



let the length be nearly nine times the diameter C, and its external diameter D muft be' 



1,8 C. This additional piece will Increafe the expenditure as 24 to I2,i. (Experiment 



XVI. ) By this means the quantity of water will be increafed by the two adjutages ABC D, 



in the. proportion of 24 to 10. 



♦ Boffur,,Art, 509. 



Att 



