Prof. Magnuses Hydraulic Researches. 95 



In consequence of cohesion, the water moving sidewards forms 

 an uninteiTupted circular surface, fig. 2, which becomes thinner 

 as the distance from the centre increases, until finally it is rup- 

 tured. The separated small masses of water gather into drops 

 and fly off in the direction of the radii. 



16. As long as the water surface is unbroken, two forces act 

 on its parts. The one is the pressure of the approaching masses 

 of water which propels them in the direction of the radii, the 

 other is the cohesion which maintains it in connexion with the 

 adjacent parts. In consequence of the latter, the velocity in the 

 direction of the radius is diminished, for a part of the force 

 which acts in this direction is expended in spreading the water 

 out. Wlien the continuity of the water surface therefore is rup- 

 tured by a solid body held at a small distance from its centre, 

 the particles of water which pass this body are only drawn to one 

 side by cohesion. The edges of the water surface, therefore, 

 continually recede from this place of interruption. The curved 

 edges which the water surface assumes in this case is shown in 

 fig. 10, at a/3 and ay. As the particles of water moving along these 

 edges are only connected with the water surface on one side, they 

 are propelled in a tangential direction much further than are the 

 particles of the water surface moving in a radial direction. 



17. If the axes of both jets, which we still suppose to have 

 equal transverse sections, lie in one plane, in other words, if a 

 central encounter of two jets having equal velocities and forming 

 an angle with each other takes place, it is evident that a water 

 surface will likewise be produced, and that this will bisect the 

 angle made by the jets, as shown in figs. 4 and 5. It is also 

 evident that this surface cannot be equally extended in all direc- 

 tions ; for if the water did not spread itself out, it would pursue 

 its path so as to bisect the angle made by the jets, that is, in the 

 direction of the resultant of both jets. When', besides this, each 

 particle of water is propelled in a radial direction from the place 

 where the jets meet, the several particles will move in curved 

 lines approaching more and more to parallelism with that result- 

 ant. The sui'face, therefore, is extended principally in this direc- 

 tion. The small masses of water which separate themselves from 

 the edges of the surface fly ofi" in the direction of the tangents 

 to their curvilinear paths. The smaller the angle aba, made by 

 the jets, the greater the velocity of the water after contact in the 

 direction of the resultant, and the smaller the pressure which 

 causes the spreading out of the water. Consequently the breadth 

 cd of the surface cdf, figs. 4 and 5, decreases with the angle aba^, 

 and the water also extends less in the direction bq, fig. 4. 



18. The thickness of the surface also diff"ers at difi'erent points. 

 At the place where the jets meet, the lateral motion of the water 



