172 



Mr KELLAND, ON THE DISPERSION OF LIGHT, 



The following Table contains the values of p deduced in the manner 

 before mentioned. 



The principal discrepancy in these results arises from the values of 

 p given by the line G, they being in nearly every case too great. 



I can only conclude from this, that our approximation ought to 

 have been carried to another term, as for G and H the value which 

 the third term introduces is considerable, and there can be little doubt 

 but that the fourth would produce a sensible effect to the fourth place 

 of decimals. It would, however, diminish the variation which the ex- 

 pression admits of, to proceed to other terms, and for that reason, con- 

 sidering our object merely to test the accuracy of our conclusions, no 

 better plan has suggested itself than to leave the expressions in their 

 present form. 



If, however, it were requisite to determine accurately the values of 

 ;;, q . . . of course the plan to be adopted would be, that of introducing 



