(\2 Journal of the Mitchell Society [December 



We exclude the value x = 0, since it obviously gives the minimum 

 lectangle, of zero area. For the present, we may omit the value 



X = ^from consideration — primarily because a negative length 



n/2 

 would ordinarily be excluded in seeking a positive area. We shall 

 revert to this case, however, in the latter part of the paper. Con- 

 fining our attention to the value + T/^rf ' ^^'^ have: 



f (A-h) = C^ -h'^^a^- 2 +av/~2h-hj- 



h2 — 



- h 



v/2 , ., 



f (A) — f (A— h) = + h- + — '1- 





7T + '' 



This is a positive quantity, since as h approaches zero, h^ remains 

 positive, the first two terms are positive, and the remaining terms 

 approach zero, since they all involve powers of h, and indeed h^ 



Proceeding in similar fashion, we derive 



f(A)~f(A + h) = ^_(— |. + h)^a^-|^-ax/2 h-h'-)' 



