518 Prof. Baly and Mr. Garrett on the Ultra-violet 



average very much better than this, and would seem to 

 .give great support to the formula. The most important 

 result obtained, however, is the arrangement of the observed 

 lines into 82 series of about 21 members each, and, although 

 no such series is complete, yet the mean wave-number 

 differences calculated from these series are far more com- 

 parable amongst themselves than those found by Miss 

 Lowater. 



There is no need to publish the whole of the calculations, 

 hut in Table IV. are given the number of the observed 

 lines in each of our series and the mean values of the 

 wave-number differences that we have found, together with 

 those of Miss Lowater's series. Our series are numbered 

 from the central line of the sub-group in each case. Only 

 one line has been observed which belongs to the 23rd series 

 on the blue side, and therefore no wave-number difference 

 can be found from this series. 



The superiority of the new arrangement of the lines is 

 manifest from Table IV. Not only are the extreme 

 values of the differences, 223*45 and 222*94, much closer 

 together than those of Miss Lowater's table, namely 223*9 

 and 222*8, but 64 per cent, of the new mean differences lie 

 within 0*1 of the mean value, while, according to Miss 

 Lowater's arrangement, only 34 per cent, lie within the 

 same limits. Then, again, the means calculated from the 

 red and blue series are the same, 223*23, and equal that 

 •calculated from the infra-red basis constants. Further, the 

 interval between any two members of any of the new series 

 is never greater nor less than the calculated interval by an 

 amount greater than can be accounted for by the experi- 

 mental error which Miss Lowater gives in her paper. As 

 was shown above, Miss Lowater's arrangement of the lines 

 can be criticised from this point of view. Every single 

 observed line finds a place in our series between the limits 

 l/\ = 32070 and 1/A, = 36646. Six lines outside these limits 

 have not been included, two of smaller frequency (1/X = 32065 

 and 3206]) and four of larger frequency (l/\ =36633*3, 

 36712*5, 36885*1, and 36922). The former two lines no 

 doubt belong to the 8th sub-group on the red side noted by 

 Garrett, while the four latter lines lie in the intermediate 

 region between the two mnin absorption band groups, and 

 therefore we have not included them since it has been shown 

 that in this region the fundamental interval varies. 



Some reference may be made to the fact that only 586 

 lines have been observed out of a total calculated number 

 of 1722. This cannot be considered as an argument against 

 the theory, for there can be no doubt that by a still further 



