358 
ASTRONOMY: W. S. ADAMS 
June 10 June 11 June 12 June 13 June 15 
-21.7(30) -22.4(30) -23.0(26) -23.7(19) -24.6(11) 
During this period the average daily increase in displacement is slightly 
over 0.5 angstrom. The decrease in the number of lines (given in parenthesis) 
shows the gradual disappearance of the absorption spectrum within this time. 
Reference has already been made to the double character of the hydrogen 
and helium lines during the interval when the absorption spectrum of Nova 
Aquilae was prominent. A similar characteristic was found in the case of 
Nova Geminorum. The less refrangible of these components shows dis- 
placements which are in close agreement with those of the absorption lines 
due to iron and other elements which have been identified. An investigation 
of the more refrangible component shows that its displacements may also be 
represented as a direct function of the wave-length. We find for the two stars 
the relations : 
Nova Aquilae: AX = 0.0075 X: Nova Geminorum: AX = 0.0048X 
The differences as computed from these equations are as follows: 
NOVA AQUILAE (JUNE 12) 
NOVA GEMINORUM 
Observed 
Computed 
0 - C 
Observed 
Computed 
0 - C 
H 
30.7 
30.8 
-0.1 
19.4 
19.7 
-0.3 
H 
31.7 
32.6 
-0.9 
20.6 
20.8 
-0.2 
m 
37.6 
36.5 
+1.1 
23.7 
23.3 
+0.4 
Ha 
49.0 
49.2 
-0.2 
At X 4500 we find the displacements 
Nova Aquilae; —33.8 Nova Geminorum; —21.6 
In the case of Nova Geminorum, therefore, the displacement of this com- 
ponent of the hydrogen lines is almost exactly twice that of the less refrangible 
component and the numerous metallic lines, while in Nova Aquilae it is one 
and one-half times as great. In other words 11, 22 and 33 angstroms, in the 
harmonic ratio 1, 2 and 3, represent very closely all the displacements found 
among the absorption lines in the spectra of these four stars with the excep- 
tion of the four narrow nearly undisplaced lines of calcium and sodium from 
which the radial velocities of the stars may be derived. These lines, like the 
broad emission bands of hydrogen and helium, may perhaps be considered as 
belonging to the stars themselves, while the greatly displaced absorption lines 
originate in an outer envelope possibly detached from the body of the stars. 
It is certain that no adequate explanation has been offered as yet to account 
for these immense displacements. Were the hydrogen and helium lines alone 
involved it is possible that some of the complex phenomena of self-reversal 
under conditions of marked variations in density and pressure might, at least 
in part, be responsible. The presence, however, of a great number of com- 
