256 PROFESSOR L. BECKER ON 
TABLE I.—contonued. 
Photo-Plate No. 3, 1901 March 18 and 20. 
Angle of inclination of plate=13°; width of slit 0-018 mm.; Imperial plate ; exposure 4:4 hours, 1°2 
h, on March 18 and 3-2 h. on March 20; clear negative; the spectrum was measured 6 times, the H-bands 
12 times, and referred to 50 standard lines ; good definition. 
A v. | Intensity. r . | Intensity. a v. | Intensity. aA ». | Intensity. 
4028 | 155 | 4251 7 | 4512 | 4 4871-0 = 
| I 105 13 
4034'8 | 0-4 15] 4260 6 6 4535 2 10 4875°1 13 =9 
4037°3 | 1 5 2 42847 | 08 7 4551 2 10 | 4879-4 1 
40440 | 0 4315°31 =O | 4562 4 11 | 4883°9 8 
4055 | 2 6 4318-4 . 4500 | 2 10 | sane ae i 
4061 | 3 y 4319-03 ib 4602 3 9 | 4900 3 3 | 
4080°76 | 4319°6 9 4607°2 | Ol 8 | 4911-4 4 
4081°51 | f 4326°9 ul 4611 13 | 9 | 4922 9+5 
4082°2 6 4335°6 12 | 4620 3 | 10 10 | 4931:2 | 0-2 3 
40857 7 4340°9 13 | 4643 6 u 49410 | 05 | 2 
4090-4 3 4343 id 14 | 4679 8 10 | 4956 2 1 
4097°8 9 | 4348°7 vs = 10} 4700 3 8 | 4978 1 15 
4102°7 10 10 | 4358-0 12 | 4735 7 6 | 5003 4 9 
4117°9 10 | 4368-9 10 | 4794 a 5D | 5025 2 15 
4121°1 9 | 4382 5 9 9 | 4833°46 | =0 | 5042 3 0° | il 
4132 5 6 6 7 4396 1°4 10 4836°5 507- 6 0-8 
4148 6 | 4423 3 | 10 | 4837-43 \q 509— 10 0:3 
41545 | 1-1 | 5 | 4427°8 | 06 9 9 | 4838°4 / P 5133 0 
4165 my 4449 2 9 | 484471 5154 : 
4187 3 Ed 4459 3 | . 10 | 4849-4 " 5175 me | 0:2 
4203°9 | 0-7 P 4473 3 “4 4855°8 9 5188 0-1 05 
4219 1:3 6 4492 3 1088 4858-0 13 5207 | 0-1 
4233 16 7 4502 6 10 4864:1 13 =9 | 5265 O-1 0 
4251 4 4512 4 4871°0 =9 | 5295 
5. Lhe three H-bands.—On photo-plates Nos. 3 and 4 three well-defined Fraunhofer 
lines are a prominent feature, appearing respectively in the neighbourhood of the 
hydrogen lines H, H, H;, and the difference between the wave-length of a Fraunhofer line 
and that of a corresponding H-line is proportional to the wave-length. Towards the 
less refrangible side of the Fraunhofer lines there are bright bands, which also occur 
on the other five photo-plates. If the wave-lengths of corresponding points of the 
three bands be compared with the wave-lengths of the three hydrogen lines, the 
differences are found also to be proportional to the wave-lengths. I conclude that the 
