382 
DR. W. M. HICKS : A CRITICAL STUDY OF SPECTRAL SERIES. 
Here however no such certain conclusions can he drawn. They may enter as links. 
Although their true connection may ultimately be definitely settled the doubt as to 
whether they give true or false scents renders the task of unravelling most 
bewildering. 
In about the region to be expected we find the set 
(1) 1988072 1778-42 (5) 2165914 816-30 (lO) 2247414 
showing from their separations and order of intensities an indubitable satellite set of 
Dg type. Below these come a number of indubitable doublets of type, and then a 
number of strong lines of Du type. There are also in this region an extremely large 
number of lines with separations between 1780—1785 corresponding to the enlarged 
links already found in the KrD spectrum. This portion of the spectrum is set out 
together with their separations in the following table :— 
(2 ft) 17903-44 
(3) 19632-44 
1780-84 
1772-81 
(7) 19676-25 
1781-23 
(1)19785-84 
(3) 19815-84 
(1) 19829-47 
(1) 19880-72 
1778-42 
(1) 19942-53 
1775-45 
(1) 19959-64 
1772-60 
(.371) 18238-60 
(1) 19989-72 
1780-27 
1778-86 
(1) 20017-46 
1783-71 
1783-06 
(1) 20021-66 
1779-51 
(7) 18266-88 
(2) 20029-12 
1774-85 
(2) 20041-73 
1782-55 
(4) -20080-93 
1784-54 
1786-02 
(1) 20107 
(1) 20305-60 
(6) 20312-70 
1783-72 
(4) 20320-25 
1776-17 
(5) 22096-45 
(1) 20333-22 
1774-92 
(3ft) 22108-14 
(5) 20443-29 
(5) 20454-88 
(1) 20467-90 
(6) 20470-75 
(3) 21413-28 
(1) 21457-48 
(5) 21659-14 
(10) 21717-98 
815-30 
(10) 22474-44 
(1ft) 21732-24 
(6ft) 21769-99 
(10) 21801-17 
812-77 
(6) 22545-01 
(1ft) 21824-28 
(1ft) 21865-47 
1784-765 
(2) 2.3650-23 
(1ft) 21866-95 
1783-28 / 
f (7) 
1 
20500 
13 
1784-68 
(2) 
22284-82 
1777 
11 
1 
(9) 
18723 
02 
1 
814 
13 
A2ft) 
17908 
89 
(3) 
20529 
92 
1780-35 
{In) 
22310-27 
(8) 
20559 
08 
1785-64 
(<lft) 
22344-72 
(1) 
20581 
64 
Before however considering these lines in detail it will be desirable to take here a 
preliminary discussion which involves a new fact in series relationships, and at the 
