OF ARTS AND SCIENCES. 239 



If, for insUiuce, we apply (38) to 



■( z — a a- r- 



w = ^^ II 



\ 



which yieltls (5), we get 



1 r^ r^ — 2 ^2 



±X-{{z-af a' (^_>_ 



a 



which, after reduction, gives (30). 



By meaus of (38) and other similar equations, a great number of 

 cases of flow inside circular disks may be found. 



Jefferson Physical Laboratoev, 



Cambridge, Mass., August 1«, 1891. 



