428 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



o 



M 



'~r~^ — 



^-g- 



Values of Correction 





;> 





Curve sliowing relation between the correction factor and g, the 

 projection of the larger corner from the smaller. 



The case where .9 = has for correction factor - (1 — log 2) 



TT 



2 A 

 The case whore <j — ^ has for correction factor — (1 — log 2) 



TT 



The general case is 



h (a — \ /tt , -\ , , , Ad 



tan-iy,! + 1 - log 





Ja 



Vaw ' '^i 



a + 1 



log 2) 



where - 



li 



ct — 1 , ^, . . , , r; , a—\(w ,-\ 2ii 

 = - -^ and the quantities plotted are-; and ( — tan-i-\/« 1— loe ■ 



