HYDRODYNAMICS. 



507 



f Vtttd*. 



SECT. VIII. Experiments on the ascent of Water in Jets 

 d'eau, either vertically or obliquely. 



L*T 

 1,3. 



Experi- 

 ments on 

 Jets d'eau. 



with two vessels A BCD, DCBA, Fig. 2. and Fig. 3. 

 whose internal diameter is 6 inches, and height 3 inches. 

 The length of ED was one foot, and E\ two feet. 



The diaphragm EF was pierced with an aperture G, 6 THE custom which formerly prevailed of decorating 



lines in diameter; covers DC, AB with different orifices, pleasure grounds and public squares with jets d'eau, ?," J cts 



were placed successively on the cylinder, and the cy- rendered the subject of the present Section much more 



linden were inverted, as shewn in the two Figures. A interesting than it is at present. The phenomena of 



jets, however, are still of importance in a scientific point 



narrow opening, 1 8 lines broad, was cut through the 

 whole length of the cylinders, and covered up with glass, 

 in order to see what was going on within, and near 

 the diaphragm EF was perforated a small aperture /, 

 which could be either opened to admit the air, or shut 

 up with wax. The following result* were then ob- 

 tained. 



rp. 1. The cylinder Fig. 2. being completely filled, 

 and the hole / shut, orifices of 6, 12, and 21 lines were 

 successively applied. In alljthese cases the water in 

 the lower compartment abandoned the diaphragm when 

 the height EH of the water was about ti or 7 lines. At 

 the instant ut separation a whistling noise was heard, 

 arising from the passage f the air from the upper to 

 the under compartment. 



Etp. 2. By inverting the cylinder as in Fig. 3. and 

 applying the same orifices, the very same effects were 

 produced. 



Eip. 3. The vessel having the position in Fig. 2. 

 the hole t being now opened, and the orifice at M b. inn 

 6 lines, the separation took place when EH wa about 

 1 4 inches. 



ETD. 4. When the diameter of the orifice at M was 

 four lines, the separation took place when EH was six 



of view ; and as the fashions of former times may a^ain 

 return, it would be inexcusable to omit altogether the 

 consideration of this branch of Hydrodynamics. 



According to the theory of vertical jets, which has 

 already been explained under Chap. I. of Part It. they 

 ought to rise to die same height as that of the surface 

 of water in the reservoir* Irom which they How. 1 his, 

 however, is not found to be the case in practice. The 

 friciion of the water on the sides of the tubes, the re- 

 sistance of the air, and the obstruction of the descend- 

 ing drops, all conspire in diminishing the altitude to 

 which water would otherwise be projected. 



In the experiments made by BO-MU, lie employed PLAT* 

 a large reservoir A BCD, Fig. 4. and 5 to which he CC XIX. 

 fitted horizontally two tubes BE of white iron, closed f V- *> 5 - 

 at the end E, and open at the end next the reservoir. 

 Each of these was six feet long. The diameter of the 

 first was 3 inches S lines, and that of the second from 

 y to I lines, and on the upper surface of these tubes 

 ajuUge* of different sue* were placed. Around the 

 mis of each ajutage was soldi red a tube of white 

 iron, wbose diameter was grater Uuui that of the aju- 

 tage, in order to be able to stop the jet by means of 

 cork, which goes uito the white iron tubes. The fol- 

 lowing Table contains the results of the experiments. 



TAILS XIII. Skewing He AMndet to mkiek J*, me through Aj*tge* of different for*,, the Altitude of tht 

 Retenotr being El**n Feet, reckontmgjrom tke wpfer turfu* O j t t,e horizontal T*ba OE, OE. Fig. 4. and 5. 



