428 



PROCEEDINGS OP THE AMERICAN ACADEMY. 



'o 



00 1> 

 3 



o 

 II 



Values of Correction 



+ 





T^ — 



+ 



Curve showing relation between the correction factor and g, the 

 projection of the larger corner from the smaller. 



The case where a = has for correction factor - (1 — log 2) 



IT 



2 h 

 The case where <j = co has for correction factor — (1 — log 2) 



IT 



The general case is 

 /( ( a — 1 



r^r(!--°-v°>— ^i| 



li [a — 1 /7r 



( r, - tan_ ' V'A " lo S -^TT +( 1 - log 2) 



1_ I 



where f = - — - and the quantities plotted are 9 - and °" " ' ^ 



/( 2 V« A 



( - — tan-i/i/a |— log . 



v«v 2 y «+i 



