HYDRODYNAMICS. 



I Wilt r 



- * 



. 



*< : 



Four cubical feet 

 were discharged in 



Rectilineal tube 45" 



Curved tube 50 



Rectangular tube 70 



The following results were obtained by Du Buat, re- 

 ing the effects produced by bent tubes 1 inch in 

 ieter, and of different length*. 



Number of 



\K\t M 



Tube 1 inch 

 n diameter 

 and 117 

 inches in 

 length. 



Tube 138 

 nches long. 



Tube 1 1 7 



Tube 138} 



nclie- l.ii:j. 

 Tube 737 



336 

 236 



,'|. : 4 

 324 34 

 136 

 ..'I U 

 124 34 

 1036 



436 



436 

 236 



1:1 .u 

 136 



436 



.; (i 



Velocity 



per fecund 

 both in 



A'.n.i-:iU-!.'n 

 of the head of 'UK 

 wiser which 



<U'.|- 



hi.'ir. 



M5 



84.9*5 



M.'.n:. 



Ml+3 



71 59 



58808 



58.438 



M i .:s 

 .> i < 

 58.438 



29.33 

 28.657 



led from 



t'v i.-r. 



1 1..',,.. 



2.49 



1.5 



1.5 



1.12 



0.75 



0.75 



0.37 



5.905 



1.64 



1.5 

 0.75 

 0.75 

 0.37 



0.41 



Utta 



49 

 1.66 

 1.66 

 1.24 

 0.83 

 0.83 

 0.41 

 5.905 



1.59 



1.57 

 0.78 

 0.78 

 0.39 

 0.396 



0.378 



The but column of the preceding Table U computed 



V'I'K 

 from the formula - ; V being the velocity, t the 



ine of the angle of the bending, n the number of bend- 

 ing*, and m a constant quantity, which M found to be 



nearly 300. Hence - - U the measure of the resist- 



PLATE 



Number of 

 aim it pvti. 

 ... . 



1 .... 

 s . . . . 



5 . . . . 



VOL. II. PART II. 



Time la which lour 

 fabkml feet of viler 



were discharged. 

 . . . . 109" 

 ... 147 

 . ... 192 

 . ... 840 



Dichrge 

 of Water 



Tubes. 



M. Venturi employed a tube of the form shewn in 

 fig. 1 8. The orifice A ha* the form of the contracted 

 rein, and the rert of the tube is interrupted by various 

 i of it* diameter. The following are its 



UM 



A 11.2 



atB, C, F, G, . . . 9 

 Diameter of the enlarged part* 4* 

 Length of B< , <i. 9cc. ... SO 

 Length of CD, EF, (ill, ... 13 

 The length of the enlarged parts was variable, 

 being at one time 38, and another 76 lines, 

 with the tame effect in both. 



By mean* of this tube, the following resulu were 

 btaincd under A nreature of 32.5 ' 



505 



Venturi afterwards applied to the same orifice a tube 

 having the same form and the same diameter as ADC, 

 but cylindrical throughout, and without any enlarge- 

 ments. It was 36 inches long, and the time in which 

 four cubic feet were expended was 148''. w p-y-W 



" When the fluid passes from C," says Venturi, " to 

 the middle of the enlarged part DE, part of the motion 

 is directed from the direction CF towards the lateral 

 parts of the enlargement. This part of the motion is 

 consumed in eddies, or against the sides. Consequent- 

 ly there remains so much the less motion in the follow- 

 ing branch FG. This is also the cause which destroy - 

 or weakens the pulse in the arteries beyond an aneu- 

 rism. 



" From this consideration we are justified in con- 

 cluding, that if the internal roughness of a pipe dimi- 

 nishes the expenditure, the friction of the water against 

 these asperities does not form any considerable part of 

 the cause. A right lined tube may have its internal 

 surface highly polished. Throughout its whole length 

 it may even' where possess a diameter greater than the 

 orifice to which it is applied ; but, nevertheless, the ex- 

 penditure will be greatly retarded if the pipe should 

 nave enlarged parts or swellings. This is a very inte- 

 resting circumstance, to which perhaps sufficient at- 

 tention has not been paid in the construction of hy- 

 draulic machines. It is not enough that elbows ! 

 contractions are* avoided ; for it may happen, by an 

 intermediate enlargement, that the whole advantage 

 may be lost which may have been procured by the in- 

 genious dispositions of the other parts of the machine." 



Eyteltrdn't Experiment* on additional Tulxt. 



The experiments of M. Eytelwein on additional tubes Eytelrein'i 

 confirm the general results obuiiu< I l>\ Vtnturi. Tlie f*"- 

 following are the leading resulta which he obtained : mcn<< > 



Co-effiri- 



IbUoofuwDu- enuforthe 

 CO*TJC. velocity. 



Shortest tube that will cause 1 



the stream to adhere every >. 8 125 to 1.0000 6.5 



where to its tide* . . . . J 

 Short tubes, having their 1 



lengths from 2 to 4 times > .82 6.6 



their diameters J 



Conical tube approaching to] 



th form of UMMIM om-f.92 7.38 



trarta 



The same tube with its 



edge* rounded off .... 

 A too* projecting within the ] 



reservoir . 



'- 

 , Q 



7.8G 

 4.0 



M. Eytelwein U of opinion, that Venturi's assertion 

 that the discharge of a cylindric tube may be inc-i <.-.<- 

 ed in the ratio of 24 to 10, is not generally correct, 

 and that when the tube is very long, scarcely *ny addi- 

 tional expenditure is obtained by the addition ol'such .: 

 tube. From a great number of experiments which he 

 made with different pipes, he infers that a compound 

 conical pipe, such as that shewn in Fig. 16, may in- 

 crease the discharge to 2.J as much as through a simple 

 orifice, <* as 24 to 10, as stated bv Venturi, or to more 

 than half as much more a< would fill the whole section 

 with the velocity due to the height ; but that where a 

 considerable length of pipe intervenes, the additional 

 orifice appears to have little or BO effect. 

 Si 



