212 



Scientific Proceedings, Royal Dublin Society. 



spectrum — as corresponding to m = 2. The values of m for tlie 

 other lines will then be as in the following Table : — 



The Table also gives the values of x (by observation) and of % 

 (by calculation) of the derived curve. If we pass a parabola with 

 its axis vertical through three of these points, viz. through 

 S3 = 250 %; = 111-r z, = 27-7' 



x^ = 169-6878 X, = 3027762 x, = 385-5080, 

 we find, by the method of the last paragraph, that 

 log P = 3-774,0300 

 a = 3337-4120 

 b = 1438-35 

 Putting these values into equation (5) and computing the values of 

 n (i. e. x) for the other terms of the series, we find 



