VIEWS OF RUNNING WATER. 



655 



drical and vertical in its origin, becomes necessarily the seat of 

 horizontal oscillations independently of the vertical vibrations 

 which were first considered. Not a single molecule of which the 



Fig, IS. Fig. 14. Fig. 15. 



Instantaneous Photographs showing the Fokm of Liquid Sheets escaping from a 

 Canal or from a Prismatic Vessel with Parallel Walls. 



mass is composed follows a straight or parabolical line in its fall. 

 All, without exception, describe a sinuous or zigzag course. Such 

 is the general phenomenon. Let us follow out some of its details. 



For the jet to be rigorously 

 cylindrical in its origin is not 

 a sufficient condition of its pre- 

 serving that form. When it 

 issues horizontally in full gush 

 from a fountain, the parabolic 

 trajectories, upper and lower, 

 lose their parallelism and cause 

 by approaching one another a 

 flattening of the jet. From this 

 fact arise horizontal undula- 

 tions, only slightly marked, it 

 is true, but which suffice, if the 

 light is favorable, for produc- 

 ing the illusion of swellings 

 and contractions (Fig. 12, xxi). 



,..,.. ' Fig. 16. Fig. 17. 



Even When a liquid Vein ISSUeS Escaping Liquid Veins and their Profiles, 



vertically from the bottom of a As shown by Keflection at 45 in the 



-\ -1 t i 1 -i Vertical Plane. 



vessel by a circular hole, it as- 

 sumes a helicoidal form in consequence of a motion of rotation 

 which develops gradually within the vessel. This is independent 



