DR. W. M. HICKS: A CRITICAL STUDY OF SPECTRAL SERIES. 



Se. 



The lines allotted by RUNGE and PASCHEN to the D series present a quite different 

 appearance from the normal, although there can be little doubt but that they form 

 the SeD. The weak satellite lines after the first appear on the violet side of the 

 strong lines, whereas in all other yet known cases they lie on the red side. Moreover, 

 the strong lines instead of standing by themselves are each the first members of 

 complete triplets for m = 4, 5, 6, 7 (m = 4 is the first set observed). The numbers in 

 the table are calculated with D(oo) = 19274. The value of S(<) calculated from 

 (4,5,6) is 19275*10 (2'4), but it requires, as in S, a further diminution of over 1 

 (i.e., within error limits) to bring in the fifth line. Hence D() cannot be far from 

 19274. The value of S is calculated from A, + A a = 161 x90-40w*, and consequently 

 must be considered very exact. A, and A 2 are calculated by transferring 15w* from 

 calculated A 2 to A,, making the values 28ix36r62w s and 12 x 361*61^. The 

 numbers calculated fi-om the observed values are given in a separate list. A glance 

 shows that the usual regularity is here quite upset, and one feels convinced that 

 some disturbing influence must have been at work. If we examine the wave numbers 

 of the first four sets as exhibited in the following table, we notice that for the first 



J~ (14149-27)? (3)14252-84 (3) 14300'31 



:4 1(5) 14156-19 (3)1425976 



f(6) 15803-95 (3) 15907'80 



5 1(1) 15804-95 (1)15908-67 (4) 15953'89 



J(5) 16768-10 (1) 16872-15 



3 1(1) 16769-17 (1)16872-67 (3) 16917"33 



f(7) 17375-92 (l) 17482'33 (3) 17523'15 



= 7 1(2) 17379-58 (7) 17483'00 (4) 17527'20 



set, we should expect a weak satellite about 6'92 behind 14156, which is not likely 

 to have been observed in that region far in the red. Its difference, 3129, is close 1 

 55^ = 3118, and provisionally we may regard this as normal The next two triplt 

 (ro = 5,6) give separations respectively TOO and 1'07, corresponding to a lateral 

 displacement in D() of S, (S, actually gives '925 displacement), 

 separation is 3'66 corresponding to a displacement of S (4*. gives 3*7). 

 for this line the intensity has increased from 5 to 7 and gives suspicion of a d 

 ment by addition. If we suppose that the chief lines have a lateral displa 

 ( + J)D () it means adding 370 to their wave numbers, i.e., they are now 

 and 16771-80, and they come 27, 2'63 in front of their satellites, which, allowing i 

 errors in observation, is in fair order with the first separation 6'95. 

 only is the strong line abnormally more intense than for m - 

 VOL. ccxur. A. 3 B 



