130 



THE ROYAL SOCIETY OF CANADA 



To obtain the ripple, apparatus as shown in Fig. 1 was used. 

 By means of a filter pump (V, a tube leading to filter pump), the 

 reservoir R was exhausted and when the tap E was opened, keeping 

 tap F closed, the water ascended the tube T. By opening F, it could 

 be lowered again. P is a pressure gauge and B is a barometer; by 

 means of these, the pressure in the reservoir could be kept constant, 

 thus, ensuring the same velocity of the liquid surface in tube T. To 

 vary the velocity of the surface, a number of capillary tubes in parallel 

 were introduced, these being connected by means of rubber tubing to 

 the larger distributing tubes C and D. By means of clips, each or 

 all of these could be shut off. The velocity could further be altered 



Figure 1 



by changing the pressure in the reservoir. To measure the advance 

 of the ripple, an instrument, H, similar to a hydrometer but calibrated 

 in millimetres was used. This was allowed to ride on the surface of 

 the liquid as it ascended the tube and thus, the advance of the ripple 

 was measured directly. 



The relation between the advance of the ripple and the velocity 

 of the moving surface was first studied. The liquid was allowed to 

 ascend to the top of the tube each time, measurements were taken as 

 the surface passed a selected point, and its velocity measured by tak- 

 ing the time for it to pass from one point to another, these points 

 being equidistant from the selected point. Using a constant velocity. 



