Prof. Magnus's Hydraulic Researches. 91 



Experiments on the mutual action of tivo Jets. 



_ 4. In these experiments I used an aj^paratus consisting of a 

 zinc vessel containing about a cubic foot of water, in the bottom 

 of which a glass tube, 15 miUims. in interior diameter and r™3 

 long, was fixed perpendicularly. At the lower extremity of this 

 tube was a cock, and to this was affixed a brass tube witli two 

 branches inclined to each other at an angle of 30°, and provided 

 with long tubes of vulcanized india-rubber. These tubes had 

 also an interior diameter of 15 millims., and were provided with 

 brass tubes of the same interior diameter and 0'"-25 long, to 

 the anterior ends of which caps were attached whose thin walls 

 were pierced to form the efflux orifices. These tubes were so 

 disposed upon a fixed frame, that any required direction could, 

 be given to the water-jets issuing from them. Eig 1, Plate I., is 

 a view of such an apparatus. In order to dispel the air lodged 

 in the tubes of brass or india-rubber, and to prevent the admis- 

 sion of air through the orifice in the cap i during the prepara- 

 tion of an experiment, it was necessary to be able to close the 

 tubes completely. For this purpose other caps, qq', without 

 orifices, were in readiness ; these could be placed over those with 

 orifices by sliding them over a thicker part of the tube at jjp'. 



As it was necessary during the experiments to be able to 

 change slightly the direction of the jets, the tubes were fixed to 

 a separate apparatus, by means of which this could be accom- 

 plished with perfect security. The brass tube connected at w 

 with the caoutchouc tube was fixed, by means of the circular 

 clasp nn, to the brass piece Ik. The spiral screw r kept k from 

 the piece mm, at a distance which could be regulated by the 

 Bcrew s. To the piece mm a cylindrical pin was fixed capable of 

 turning in the socket ffff. This socket was fixed by a clamp and 

 screw, zz, to the frame. In this manner a horizontal or a vertical 

 rotation could be given to the tube top. In order to raise and 

 sink it parallel to itself, a screw thread was cut on the socket ^^, in 

 which the ring z;y could be screwed up and down. By this means it 

 was possible slightly to raise or sinkm/n,togetherwith its pin,in^</. 



5. From the investigations of F. Savart*, it is known that 

 when two jets, issuing with equal velocity from two equal circular 

 orifices, whose axes fall in the same right line encounter one 

 another at places where each is still unbroken, they form an 

 almost circular surface perpendicular to the direction of the jets. 

 Such a surface is shown in fig. 2. 



6. When the axes of both jets, being still parallel, do not fall 

 in the same right line, the water surface which is formed when 

 they encounter one another is inclined to the direction of the 



• * Annates de Chimie et de Physique, 2nd series, vol. Iv. i). 257. 

 H2 



