Fiar. 1. 



Lord Rayleigh : Investigations in Capillarity. 325 



(corresponding to Tate's law) that the weight is proportional 

 to surface-tension. 



The entries under the heading " Metal " relate to experi- 

 ments in which the glass tubes were re- 

 placed by metal disks, bored centrally and 

 turned true in the lathe. The water was 

 supplied from above through a metal tube 

 soldered to the back (upper) face of the 

 disk (fig. 1). At the time of use only the 

 lower face was wetted. 



A plot of both sets of numbers is shown 

 in the figure (2). The two curves prac- 

 tically coincide up to diameters of about 

 '4 inch, after which that corresponding C 

 to the disks falls below. The lower curve shows some 

 irregularities, especially in the region of diameters equal to 

 '6 inch. These appear to be genuine ; they may originate in 

 a sort of reflexion from the circumference of the disk of 

 the disturbance caused by the breaking away of the drop. 

 It is possible that at this stage the phenomenon is sensibly 

 influenced by fluid viscosity. 



Fi<?. 2. 



That the size of the bore should be of secondary im- 

 portance is easily understood. Up to the phase of instability, 

 the phenomenon is merely a statical one, and the element of 

 the size of the bore does not enter. It is only the rapid 



