Exper'mir.is en the lateral Cetnmt/htcathn if Mothn i» Fluids, fjg 



dimenfions in lines AB = EF= i8; AC = ii; CD=: 15,5 ; CG =^ 49 ; and this 

 fube being applied to the orifice P, fig. i, under a charge of 32,5 inches, the four cubical 

 fcQt of water were emitted in 27",^. 



We have feen that, in the third experiment, under like circumfl;ance«, the orifice through 

 a thtn plate nfforded four cubic feet of water in 41". The contra£led vein was 0,64 of the 

 orifice. Confequently, by following the enunciation of the theorem, the expence through 

 the pipe A B F ought to be made in 26'',24. The experiment falls ftiort in the quantity 

 l",26. 



Experiment XIV. Between the two Conical tubes of the preceding experiment is'inter- 

 pofed a cylindrical tube three inches long and J5,5 lines in diameter. The interpofition of 

 the cylir.der between the two cones was as in fig. 13. This addition retarded the expendi- 

 ture i", the time now being 2ii",^. 

 ; Experiment 'K'V . The charge of the refervoir being conftantly 32,5 inches, the portion 

 of the tube A B C D, fig. 1 1, had the fame dimenfions as before ; the tube C D F E was 78 

 lines in length, and its diameter 23 lines. To this horizontal tube I added three glafs tubes ; 

 the firfl: D X at C D ; the fecond N Y at the diftance of 26 lines from the firft ; and the 

 third O Z at 26 lines diftance from the fecond.- The. lower extremities of thefe three tubes 

 \<'ere plunged in the mercury of the veffel C^ When the water was fufFered to flow through 

 the tube AE F B the mercury rofe 53 lines in the tube D X ; 20,5 in NY, and 7 in O Z. 

 Thefe quantities correfpond with 62 inches hoight of water in DX ; 24 inches in N Y ; 

 and 8,1 in O Z. The expenditure of four cubic feet was efFcded in 25''. 



I cut ofFthe portion PN F E of the tube, and the remaining pipe ABN P emitted the 

 <^'me quantity in 31^'. 



In the truncated conical tube A C P B D N, the fe£l:ion P N is to the fe£i!on of the con- 

 tracted vein (namely 0,64 of the fe£tion A B) as 41" to 30". In the experiment with this 

 laft truncated tube the retardation is confequently no more than i"lefs than the theory. 



In the entire tube C D FE we have ^ 62 + 32,5 : a/ 32>S = W : 24". The difference 

 of 38 inches elevation of water in the two tubes D X, NY, muft arife from the motion of 

 the -fluid from C to P ; it is i-i3th lefs than by the theory. The lofs is fucceffively greater 

 in the two portions P Q., Q_E. The reafon of this is, that the ftream defcends as it moves 

 from C D, fo that the lateral communication not being made uniformly through the whole 

 of any one feclion, the different parts of the current acquire irregular motions, and even 

 eddies within the tube; whence the jet comes forth by leaps and irregular fcattering.— 

 Thefe uncertain motions cannot be reduced to the theory, and manifefl themfelves the more, 

 the longer or the more diverging the fides of the tube. The efFc£ts confequently remain to 

 be afcertained by experiment. 



Experiment XVI. I conftru£ted a tube CD FE as before, (fig. 11) 148 lines 5ong, and 

 27 lines in diameter at E F, the refl of the apparatus being the fame as in the foregoing 

 experiment. The expenditure of four cubical feet was efFefled in 21'''; the inequality and 

 irregularity of motion in the flream were greater in this experiment than in the foregoing. 



It was ufelefs to prolong the tube CD FE beyond 148 lines ; for the ftream did not in 

 that cafe fill the portion of tube added beyond that length, and the expenditure remained 

 conftantly at 21^'. This expenditure is jiearly double what took place through the fimple 

 aperture in a thin plate ; and it is the greateft I have been able to obtain by additional 

 tubes, the axis of which had an horizontal pofition under a charge of. 32,5 inches. 



N n a It 



