106 Prof. Magnus's Hydraulic Researches. 



is present, §§ 44, 45 ; they do not, however, encounter centrally. 

 Hence the jet assumes, as seen in the drawing, a form exactly 

 similar to that described in § 11, and represented in fig. 8, Plate I., 

 which results when two separated jets meet at an angle, but not 

 centrally. Each of the edges moves in a spiral line about the other, 

 and between them the water surface is extended as a membrane. 

 The edges may move at a tolerable distance from each other, and 

 need not meet, as was necessary in the case of two separated 

 jets, § 11. 



53. The more considerable the hindrance at E, the more 

 spiral-shaped does the jet appear ; for with increasing breadth 

 of the hindrance, the edge Af^g^h^ deviates more towards D, 

 where the hindrance is placed. At the same time the two edges 

 not only remain at a considerable distance from each other, but 

 it occurs sometimes that the mass of water between them bursts, 

 and that then each continues its own path, like two separated 

 jets. The phsenomenon is then just like that described in § 11, 

 and depicted in fig. 6, Plate I., which is seen at the encounter 

 of two separated jets. 



54. Instead of employing a hindrance at E, a spiral-shaped 

 jet may be obtained in several other ways. It is only necessary 

 that both the thick edges which are formed as soon as the mass 

 of water has left the orifice, should not encounter centrally. If, 

 for example, the aperture be so altered that it is not everywhere 

 of equal breadth, but something of the form of fig. 16 c, the jet 

 will have the previously described, § 51, spiral form. It also 

 does not fall vertically, but is deflected a little towards the side 

 upon which the aperture is broader. 



55. If the narrower part of the aperture is situated, as in 

 fig. 16 d, just in the middle of the broader part, the jet is not 

 spiral-shaped, but has a similar form to that described in §§ 44 

 and 45, and depicted in fig. 15 a and b, which was obtained from 

 an aperture having everywhere the same breadth, and in which 

 there was no hindrance to the afflux. 



56. There are, doubtless, besides the hindrance produced by 

 the metal plate E, § 51, and the changed form of efflux orifice, 

 § 54, other kinds of hindrances and changes of form of the 

 efflux orifice, by which the spiral shape of the jet can be pro- 

 duced. But even with an orifice of perfectly regular form, and 

 in the absence of any hindrance, the jet assumes the spiral shape, 

 especially when such a motion is by any cause produced in the 

 water as to render the afflux to the aperture irregular. 



57. It has been already remarked, § 37, that a rotatory motion 

 occurs whenever a special arrangement, such as the tranquilizer 

 described in § 38, is not employed. It was also explained there 

 why the water assumes such a motion. 



