4 Prof. Maguus on the Motion of Fluids. 



not constant ; and that if the diameter of the orifice be increased, 

 that of the tube de must increase, not iii the same but in a less 

 ratio. This is probably to be referred to the more violent mo- 

 tion imparted to the fluid in A by the application of a stronger jet. 



8. The experiment was so modified that a vertical jet was 

 projected upwards into a vessel with an aperture at the bottom, 

 in which a vertical tube was fixed. To prevent, in this arrange- 

 ment, the outflow of the water, the ratio of the diameters of 

 the tube and orifice must be considerably smaller than in the 

 former case, perhaps that of 1 to 2. This is doubtless owing to 

 the fact, that the motion of the fluid exerts here a more dis- 

 turbing influence than in the experiment with the horizontal 

 tube. 



9. These phsenomena connect themselves immediately with 

 those made known by the excellent investigations of Felix Savart 

 on the deportment of a water-jet projected against an immove- 

 able plane*. The same investigations inform us of what takes 

 place when two water-jets meet each other from opposite direc- 

 tionsf. I have repeated these beautiful experiments. When 

 two jets of equal diameters and equal pressure meet each other, 

 so that they have a common tangent, the water moves in a plane 

 perpendicular to this tangent, and forms an almost circular 

 transparent disc, fig. 4, which is surrounded by a circular trans- 

 parent rim, the latter being evidently caused by the water form- 

 ing itself into separate masses, which are driven out radially in 

 all directions. 



When the axes of both jets are parallel, but not in the same 

 straight line, that is to say, when one of them is a little higher 

 or lower than the other, the water moves unaltered in a plane 

 inclined to the tangent of the jets. 



If the cross sections of the jets remain equal as before, and if 

 one of them move with greater force than the other, the plane 

 changes into a curved surface, the concavity of which is turned 

 towards the side from which the weakest jet proceeds. When 

 the difference of pressure is greater, the surface closes up ; and 

 the greater the difi"erence, the greater will be the curvature at the 

 place where the jets meet each other. When the cross sections 

 are diff'erent and the pressures equal, a curved surface is also 

 formed, the concavity of which is turned towards the side of the 

 smaller jet. But when both the diameters and the velocities — 

 that is to say, the pressure under which the jets are projected — 

 are different, and when the pressure of the jet with the least 

 diameter is greater than that of the other, a curved sm-faee is 

 also formed, the apex of which, however, as long as the ratio of 

 the diameters of the jets does not exceed that of 1 to 4, lies close 



* Ann, de Chim. et de Phys., ser. 2. vol. hii, p. 337. 

 t Ibid, vol.lv. p. 257. 



