ON THE MEASUREMENTS OF WAVE-LENGTHS. 
101 
The Spectrum of Aluminium. 
Scale- 
numbers. 
Description of lines. 
Wave¬ 
lengths. 
Eemarks. 
15-5 
Strong, short. 
4511-0 
A comparison of the map with the 
15-85 
f Strong, short. 
4518-3 
photograph of this spectrum 
17-66 
Strong, very short. 
4477-2 
will show that most of the 
19-42 
Strong, very short. 
4445-2 
short lines photographed are 
49-85 
f VERT STRONG, CONTINUOUS, sharp, ex- 
due to iron or other impurities. 
tended. 
3960-9 
51-16 
Vert strong, continuous, sharp, ex- 
tended. 
3943-4 
70-02 
J 
Strong, short . 
3713-4 
71-03 
|_ Fairly strong, short. 
3701-5 
79-17 
C A TRIPLET, VERT STRONG . 
3612-4 
80-50 
The lines are short and extended, the 
3601T 
82-07 
most refrangible being the strongest 
and most extended. 
3584-4 
142-86 
f Very strong, continuous, sharp, ex- 
tended. 
3091-9 
144-5 
Very strong, continuous, sharp, ex- 
tended. 
3081-2 
147-10 
J 
Fairly strong, short, fine. 
3065-0 
147-40 
Fairly strong, short, fine. 
3062-8 
148-12 
'Fairly strong, short, fine. 
3058-5 
148-50 
J 
Strong, short, fine, sharp, slightly ex- 
1 
tended.. 
3056-4 
148-90 
Fairly strong, short, fine. 
30536 
149-60 
Fairly strong, short, fine. 
3049-1 
179-00 
Strong, fine, discontinuous, slightly 
extended. 
2879-9 
191-76 
Vert strong, discontinuous, broad, 
sharp, much extended .... 
2815-3 
226-30 
J 
Fairly strong, discontinuous, fine 
2659-3 
228-26 
^ Fairly strong, discontinuous, fine 
265F2 
233-25 
Vert strong, short, broad, with a nim- 
bus, extended. 
2630-6 
247-75 
J 
Strong, discontinuous, extended. . 
2574-1 
249-66 
1 
Strong, discontinuous, extended. . . 
2566-9 
308-55 
^Strong, discontinuous, nebulous. 
2373-3 
309-00 
Strong, short, nebulous. 
2372-0 
309-60 
<1 
Weak, short, fine. 
2370-2 
309-94 
Weak, short, fine. 
2367-2 
310-62 
^Strong, discontinuous, nebulous. . 
2364-5 
This spectrum was from carbon electrodes, kept moistened with a strong solution of 
pure aluminium chloride. 
The photographs show faintly at one pole the two lines of copper, wave-lengths 
3273"2 and 3246'9. A number of iron lines also appear ; their wave-lengths have not 
been determined. 
