IN THE NEIGHBOURHOOD OF A CAUSTIC. 401 



The number of terms computed by logarithmic process for tliis part 

 of the integral is about 900. 



I could have wished to extend the computation as far as m = + 60, 

 so as to include perhaps one or two more maxima of the values of in- 

 tensity. Indeed, if it had been possible to foresee the approximate 

 places &c. of maxima, I should probably have commenced the compu- 

 tations to that extent. The trouble however would be great, as the 

 summation must be extended as far as tv = 2 5. Should any person be 

 disposed to go to that extent, I would recommend that the summation 

 of the values computed in this Paper should be also extended, for the 

 values of w/ beginning with + 30. 



I subjoin a Table of the different sections of the summation and re- 

 maining integration for all the values used in this Paper. 



