436 



Mr. E. H. Kidout on some Effects 



take alternatively opposite directions, forming two complete 

 streams with about 400 vibrations per second. On substitu- 

 ting a straight tube for the jet ; figures of great beauty were 

 obtained. 



Fig. 2 shows a simple wave free from harmonics. The 

 phase of the wave relatively to the lever's motion is so strongly 

 marked, that it is not destroyed by passing through tortuous 

 tubes 2 feet long. When the lever presses the tube at any 

 but a right angle, the figures are more complex and show a 

 tendency to rotation. 



A wave with harmonics produces minor streams (fig. 3) in 



Piffs. 2 and 3. 



P P. Figure resulting from primary waye. 

 H H &c. Harmonics. 

 J. Straight tube. 



addition to the primary one. I have shown in ' Nature ' 

 (Oct. 3, 1878) that a flame is capable of producing harmo- 

 nics of its primary note ; and this makes the analogy complete 

 between gaseous and liquid columns, in their behaviour to 

 sensible vibratory motion. 



The experiment analogous to the ordinary sensitive flame 

 was attempted by immersing a sensitive jet in a vessel of water 

 and passing a coloured liquid. The jet always " roared " when 

 a higher pressure than -J in. water was used. Near the critical 

 point I could not produce any marked effect by applying to 

 the water a 4-inch tuning-fork. Possibly larger apparatus 

 would give better results. While working with this, I was 

 struck with the great depth to which a stream of the liquid 

 will descend under a very small pressure from a non-sensitive 

 jet, made by contracting a |-inch test-tube to about -fa inch, 

 and cutting off some distance below the contraction. When a 

 liquid flows through this with a fall of \ inch into a tall cylin- 



