476 report— 1878. 



in which 



«4 



(02m iy 



and 6 1 • 6 2 , depending only on the radii of the cylinders and the distances of their 

 centres, may be expressed in various forms — e.g., if e l e 2 are the angles subtended 

 by the two cylinders, at the line where their radical plane cuts the plane of their 

 axes, 



6 1 - cot \ e v 8 2 = cot \ e v 



Or again, if r be the distance of their centres, 



a _ \/{(r + a + b) (r + a-b)} + \/{(r-a + b) (r-a-b)} 



1 V{ }-V{ } 



« _ <s/{(r + a + b) (r-a + 6)}-y{(r + a-&) (r-q-6)} 



2 y{ }w{ } 



the cylinders being external. If one is inside the other, this form is only slightly 

 modified. 



These formulae are applicable to the case of one cylinder in a fluid bounded by 



an infinite plane, by putting in them b = a, 6 2 = w v l = v,u 1 =u; but the properties 

 of the fluid motion deduced from these formulae were not discussed. 



