Manchester Memoirs, Vol. xliii. (1899), No. 5- 



V. On the Slipperiness of Ice. 



By Professor OSBORNE REYNOLDS, F.R.S. 



Received and read Febrtiary jth, iSgg. 



The slipperiness of ice is, and has been, one of the 

 most noticeable, interesting, and important circumstances 

 under which we live, as well as one of the commonest. 

 Ice is not the only slippery thing in the world, but it is 

 the only one of all the solid substances which, in the 

 condition nature has left them on the surface of the earth, 

 possesses the property of perfect slipperiness. This being 

 so, and being commonly known to be so, it is certainly 

 remarkable that, whatever may be the reason, there 

 appears to have been little or no curiosity as to the 

 physical significance of the unique property which ice 

 possesses. Speaking for myself this is simply explained ; 

 ice was slippery when I was born, I never knew it other- 

 wise, and, to put it shortly, it was slippery because it was 

 ice, whereas it now seems to me that, of all the secrets 

 nature has concealed by her method of deadening curiosity 

 by leaving them exposed, in this her method has been the 

 most successful. 



The cause of my ultimately discovering the secret, 

 unsought by me, was an accident, though brought about 

 by another line of research. The other sources of perfect 

 slipperiness are complex ; a smooth solid surface covered 

 by a viscous fluid, as a well-greased board, is perfectly 

 slippery just as ice is, which fact had been taken for 

 granted much in the same way as the slipperiness of ice, 

 neither more nor LiS. 



June 6th, i8gg. 



