1890.] Slipping at the Boundary of a Liquid in Motion. 227 



in diameter due to the silver layer. Different thicknesses of silver 

 were used. The differences in the times were all within the limits of 

 experimental error. 



J. 2. 





II. In order to determine whether any slipping occurred when the 

 gradient of velocity was pushed near the limits of linear motion, as 

 investigated by Prof. Osborne Reynolds,* the difference of pressure 



* ' Phil. Trans.,' 1886. 



