618 

sea 7 URE 
[May 5, 1923 
The Total Eclipse of the Sun, September 21, 1922. 
By Dr. Wiritam J. S. Lockyer. 
So time ago an account was given in these 
columns (December 29, 1921, vol. 108, p. 570) 
of the probable expeditions which would go out, and 
the stations that would be occupied, for the observa- 
tion of the total eclipse of the sun in September of 
last year. This programme was very nearly followed, 
excepting that Mr. Evershed’s party from South 
India, instead of occupying one of the islands of the 
Maldive group, went to a station, Wallal, on the 
north-west coast of Australia, thus joining up with 
other expeditions located there. 
The eclipse track, it may be remembered, passed 
over the Maldive Islands, Christmas Island, and 
Australia, leaving that continent on its eastern coast. 
3000 
SUNSPOTS 
MEAN DAILY 
AREAS 
+60 
N. HEMISE yao 
+20 
LATITUDE OF . 
PROMINENCES- 
-20° 
POLAR 
(/RREGULAR) 
INTERMEDIATE 
(SQUARE) 
EQUATORIAL 
(wind VANE) 
1910 
5 
Fic. 1.—Comparison between prominence zones and forms of the corona. 
1890 5 
Notices R.A.S., April 1922, vol. 82, No. 6, p. 324. 
nomical Society. 
The Maldive Islands seem to have been unoccupied 
on this occasion, and the British and German expedi- 
tions to Christmas Island were so clouded out that 
no observations could be made. All the stations in 
Australia were favoured with fine weather, so a 
valuable series of records may be expected in due 
course. 
The success of the Crocker Eclipse Expedition, 
which occupied Wallal, is shown by Dr. W. W. 
Campbell’s account of the expedition which appears 
in the Publications of the Astronomical Society of 
the Pacific (vol. 35, p. 11). In the first instance, this 
expedition was organised on a modest scale, owing 
to the probable great difficulties of transport, etc., at 
this remote and somewhat inaccessible station in 
Australia. The generosity of the Australian Govern- 
ment in providing transport from Fremantle, and 
assistance both in personnel and material, altered the 
whole aspect of affairs. A much enlarged programme 
was, therefore, decided upon and was eventually 
carried out successfully. 
NO. 2792, VOL. IIT] 


By permission of the Royal Astro- 

5 1920 
The main programme was as follows : 
A pair of cameras of 5 inches*aperture and 15 feet 
focal length for application to the Einstein eclipse 
problem: the Shaeberle camera, aperture 5 inches 
and focal length 40 feet, for the photography of the 
solar corona : two cameras of 4-inch quadruplet lenses 
and 5 feet focus for the Einstein effect and other 
possible results of the sun’s surroundings: several 
spectrographs for the photography of the coronal 
spectrum: and a camera of 5-inches aperture and 
66 inches focal length for the photography of the 
form of the corona. 
Dr. Campbell’s account describes very fully the 
many and varied experiences of the trip to the 
station, the landing, the erection of 
the instruments, and the procedure 
to prevent the great amount of 
dust from affecting the mechanisms 
of the instruments. He pays great 
tribute to the valuable assistance 
rendered by Mr. H. A. Hunt, the 
Government meteorologist, charged 
with the general organisation of all 
the expeditions, and to the officers 
and men of the Royal Australian 
Navy detailed to accompany the 
expeditions to Wallal and provide 
for their needs at transfer points 
and at Wallal itself. The camp 
was quite up-to-date, receiving wire- 
less time signals and a weekly aero- 
plane mail service. ‘ 
Eclipse day proved ideal and the 
whole programme was followed 
successfully. 
Owing to the irregularity of the 
moon’s motion, the times of the © 
eclipse were not exactly as fore- 
casted. On this occasion the dura- 
tion of the total phase for Wallal, 
assigned by the “ Nautical Alma- 
nac,”’ was five minutes nineteen 
seconds. At Wallal the beginning 
of totality came about sixteen 
seconds earlier than the predicted 
time, and the end occurred about 
twenty seconds earlier. Thus, 
mid-totality was eighteen seconds 
early and the whole total duration 
lasted five minutes fifteen and a half seconds. 
The corona appeared visually small and relatively 
faint, and no large prominences were visible. 
stated that the form of the corona corresponded to 
that generally associated with sunspot minimum. 
This verifies the forecast I made in the article in this _ 
journal mentioned above, where it was stated that 
“the corona will most probably be of the ‘ wind- — 
vane’ type, in which the coronal streamers are re- — 
stricted to the lower solar latitudes, while the regions — 
From Monthly 
of both poles will be conspicuous by the presence of 
7, 
the well-known polar rifts.’’ The illustration which — 
accompanies Dr. Campbell’s paper indicates a typical — 
form of ‘‘ wind-vane ”’ corona. i= 
Dr. Campbell seems to have made supreme efforts — 
to measure, on the spot, some of his plates for the © 
Einstein effect, having previously succeeded in his — 
arrangements for securing night comparison plates in — 
the island of Tahiti. 
the expedition to the solution of the Einstein eclipse 
(See Fig. 1.) ai 
Ita 
He wished at least to make a 
preliminary statement concerning the contribution of 
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