404 PROF. F. W. DYSON: DETERMINATIONS OF WAVE-LENGTH FROM SPECTRA 
(No. 5.) Spectrum shows between 250 and 300 bright lines, but shows also 
continuous spectrum and some absorption lines. The 
definition is good from 4580 to 4100. 
(No. 2.) About 150 lines are very strongly shown on 
the violet side of H y . They are short lines standing out 
from a perfectly black continuous spectrum. If in the 
diagram A be the point of second contact, and DE be 
the crescent a little before totality, the image of the sun 
was adjusted so that the slit might pass through A. 
Spectrum No. 2 is the spectrum at B, while (5) and (6) 
are at A. 
Quartz Spectroscope .—Minimum deviation at 3650. Quartz objective focussed 
for 3750. 
(No. 8.) Taken after totality and contains 17 lines from h (4101) to Ti (3685). 
Measured for the wave-lengths of the hydrogen series. 
(No. 7.) Taken after totality. Contains 36 lines extending from h (4101) to 
Ti at 3685. 
(No. 6.) Extends from h (4101) to Sc at 3572. This photograph contains 300 lines 
in excellent definition and free from any continuous spectrum. 
(No. 5.) This photograph shows a continuous spectrum with very few absorption 
lines and 500 bright lines extending from 4180 to 3460. 
(No. 4.) Contains about 300 lines between 4170 and 3474. The brightest lines 
run through the whole spectrum, but, generally speaking, it consists of a continuous 
spectrum alongside a solar spectrum. 
(No. 3.) Contains about 150 lines extending from 4101 to 3510, and approximates 
in character somewhat to (No. 2). 
(No. 2.) Contains about 150 lines from 4101 to 3460 by the side of a solar spectrum, 
which is over exposed at the blue end, but not in the extreme ultra-violet. 
(No. 1.) Shows a few of the strong chromospheric lines in the extreme ultra-violet, 
between 3510 and 3341. The photograph has been measured and wave-lengths 
deduced, but as this part of the spectrum was obtained better in Sumatra, the 
deduced wave-lengths have not been used. 
Ovar, 1900, May 28. Third Contact. 
Flint Spectroscope. 
(No. 52.) This photograph contains about 300 lines, extending from 4670 to 4026. 
There is a continuous spectrum with a very occasional absorption line. There are a 
few lines to the red of 4670 and the violet of 4026, but the definition is not good and 
they have not been measured. 
