Theories of Microscopical Vision. By A. E. Conrad ij. 619 



Table I. 



* In column 4 the rigorous values of the integral are given, which show agree- 

 ment with column 3 even more closely than could be expected. In computing 

 these we have, of course, J 2 c cos £d/3 = 2 c sin /3, or (c being = £) simply equal 



to sin £. But we must re member that in columns 2 and 3 we have adopted 15° a.-* 



qc|| 



our unit of angle, whilst in mathematical calculations the radian = - — is the unit. 



2 IT 



Hence the value of the integral has to be multiplied by the ratio of these units, 



12 



which gives — . sin $ as the complete formula for computing column 4 



