IT'S Prof. ^lagnus's Hydraulic Researches. 



b}' the stream, which show with what regularity the drops move 

 in the swellings. 



If into the first, second, or any regulavly-formed swelling when 

 it is at its maximum breadth, a cylindrical body, for instance a 

 glass tube [c, fig. 18) of 1 centim. in diameter, be introduced 

 horizontally almost as far as the internal cylinder z z formed by 

 the small drops, but with the precaution of not touching it, the 

 swelling assumes the strange shape shown in fig. 18. The small 

 drops ])ursue their way undisturbed, so that the internal narrow 

 cyliiuler z z '\s, seen unaffected. The greater drops, on the con- 

 trary, are drawn by capillarity against the glass tube. In con- 

 sequence, however, of the velocity which the water has attained 

 in falling, smaller and greater portions of it pass continually over 

 the glass tube by a, and are thrown out as drops of various mag- 

 nitudes. At the same time a thin surface of water [z a h, fig. 18) 

 is seen, which below h collects again to an irregular mass, and in 

 which separate peculiarly-formed lines are seen by certain de- 

 gi'ees of illumination. 



170. If this portion of the jet be examined by means of 

 the rotating slit (§ 154), it appears as is represented in fig. 19. 

 The great drops are seen to be attracted by capillarity upon the 

 glass tube, and thereby assume a long pointed form. As soon 

 as they are separated from the glass they can no longer retain 

 this form, they are decomposed into several separate drops, 

 which move, however, with the same velocity, so that they remain 

 in concentric circles whose centre lies in the glass tube c. As 

 long as these drops move uniformly, they appear to the unas- 

 sisted eye like the thin surface of water z ab. But at some di- 

 stance down, more and more of them are thrown off laterally, 

 whereby the expansion of the surface is diminished. 



Examination by means of the rotating slit fui'nishes no expla- 

 nation of the pecidiar lines which, by certain kinds of illumina- 

 tion, are seen in this surface, z a b, fig. 18. Probably they depend 

 upon the refiexion of the light from different drops of equal size. 

 171. If, instead of the glass tube, a fine wire be introduced into 

 a perfectly-formed swelling, with the precaution that the narrow 

 internal cylinder z z n not touched by it, the stream is divided as 

 is represented in fig. 20. Here P denotes the fine wire, and z z 

 the narrow cylinder. If the jet having this form be examined 

 by the rotating slit (§ 154), it is seen that the drops in the two 

 limbs, P X, P Y, into which the stream becomes divided, remain 

 at equal distances from the wire P, and that the small drops 

 which form the vertically-descending narrow cylinder V z move 

 at about the middle point of the distance between each two drops 

 in P X and PY, just as they would have moved between the 

 great drops if these had not been separated by the wire P. In 



