Prof. Magnus's Hydraulic Researches. 93 



when their axes were not in the same plane, the phsenomena 

 were different according as the axes were more or less distant 

 from each other. When they were so far apart that their edges 

 only encountered each other, and when the angle which they 

 fonned was not greater than 60° or 70°, each jet, after contact, 

 continued its path, although both deviated from their original 

 directions and approached each other, so that at some distance 

 from the place of their encounter they moved in almost parallel 

 directions. At the same time a water surface was ]iroduced 

 between them, kb, fig. 6, which ended in an irregular form at k. 



11. When the angle made by the jets remained unaltered, 

 but when by a parallel displacement of one jet their axes were 

 brought nearer to one another, the phsenomenon changed, so 

 that the jets no longer moved parallel, but approached and again 

 crossed each other on their paths ; in such a manner, however, 

 that the jet which at their first encounter was uppermost, was 

 undermost when they encountered each other a second time. At 

 the same time a surface of water formed itself between them, as 

 shown in fig. 7, where ahcd represents the one jet, and afiffit^ 

 the other ; and where in the space bcdCf, the water surface may 

 be seen extended like a membrane. 



When the angle between the jets was only about 30^, they 

 crossed each other a second, and sometimes a third time, as in 

 fig. 8 ; so that each jet formed a spiral-shaped line, and the 

 spaces bcdCf and dd^fe were filled with surfaces of water. In 

 order to observe the phsenomenon in this manner, the velocity 

 of the water in the jets must not be too great, and they must 

 have besides this a suitable diameter. In the pha;nomenon as 

 shown in fig. 8, the orifices had a diameter of 3 millims., from 

 which the jets issued so as to form an angle of 30°, and to touch 

 each other only at their extreme edges. In order to obtain many 

 such successive surfaces, the orifices from which the jets issue 

 must be perfectly round, and at the same time the whole appa- 

 ratus, and particularly the efflux tubes, must be immoveable. In 

 this manner, however, about three surfaces can be obtained, as 

 well when the jets ab and ap, before contact are vertical, as when 

 they are horizontal. 



12. Each of the water surfaces bcdc, and defd^ fig. 8, appeared, 

 as already mentioned, like a membrane stretched between the 

 jets. They were not therefore plane, but of double curvature, 

 and formed skew surfaces. Neglecting this curvature, however, 

 as %ve11 as the parabolic curvature imparted by gravity to jets 

 issuing from vertical orifices, the several surfaces were all nearly 

 parallel to the axes of the jets ab and a^b^, when the latter en- 

 countered each other only at their extreme edges. 



13. When the jets did not so encounter one auothei", but had, 



