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APRIL II, 1912] 
NATURE 
153 
photographs were secured illustrating intimate 
association between prominence and the overlying 
coronal material, thus affording further evidence of 
their close connection. 
While, therefore, prominence activity is most likely 
responsible for providing and raising the material 
from the body of the sun in the various latitudes 
according to the diflerent epochs of prominence 
activity, what action is it that organises and arranges 
the streamers which extend sometimes five or six 
millions of miles into space? 
The close association between the occurrences of 
terrestrial magnetic storms and solar disturbances, 
and the results of the researches which were described 
in this institution in 1909, namely, the discovery of 
solar vortices and the presence of powerful magnetic 
fields which result from the revolution of the nega- 
tively charged particles, termed corpuscles, in them 
electro- 
—these suggest strongly a cause, namely, 
magnetic action, to explain the effect. 
being of the “slit” type, employing a 1o-ft. concave 
grating, while the other was of the ‘‘slitless” or 
prismatic camera type, in which the dispersion was 
secured by four 6-in. prisms of 45° angle. 
The lecturer then referred to the various eclipse 
parties, namely, the two British official parties under 
himself and Father Cortie, a private party under Mr. 
Worthington, an Australian party under Prof. 
Baracchi, and two other observers who went out 
separately. The great assistance which the officers 
and men rendered to the lecturer’s party can be 
gathered from the fact that 14 officers and 107 men 
took part in the observations. 
Vavau was reached on April 2, and a camp was set 
up about a mile and a half up the harbour. 
Work was commenced at once to clear the 
for the eclipse and living camps, to cut paths, 
erect landing-stages and steps. The various groups 
of volunteers confined themselves to their several 
duties, and general working parties were formed for 
ground 
and to 
Fic. 2.—A view of the eclipse camp (Solar Physics Observatory expedition). 
So long, then, as the corona can only be observed 
during eclipses, the study of its general form and its 
structure in close proximity to prominences should be 
minutely recorded and discussed. 
About the chemistry of the corona nothing is 
known. The spectroscope on many occasions has 
permitted observers to photograph the many radia- 
tions that it emits, and while numerous determina- 
tions of the wave-lengths of these radiations have 
been made, no terrestrial equivalents have yet been 
discovered. Thus its composition is still a mystery. 
For the occasion of last year’s eclipse the main 
work intended to be accomplished by the expedition 
of which I was in charge was a study on a large 
scale of the spectra of the chromosphere and corona, 
together with the form of the corona. 
For the spectroscopic work, two instruments giving 
large dispersion were constructed, adjusted, and “taken 
out, and several coronagraphs of different focal 
lengths were utilised for recording the form of the 
corona. 
The large spectroscopes were of two kinds, one 
NO. 2215, VOL. 89] 
fetching dead coral, sand, and water for the concrete 
pillars, for building the pillars, and putting together 
and covering the instrument-huts and dark-room. 
The weather experienced for the first week was all 
that could be desired in the way of absence of rain, 
but the high humidity, coupled with a high tempera- 
ture and the presence of millions of flies and 
thousands of mosquitoes, rendered the work of the 
camp formation extremely arduous. In the water we 
had other enemies in the form of sharks and 
snakes. 
At a later stage a rainy type of weather set in, and 
it was the exception to have a day free from it. 
Tropical downpours were very frequent, and special 
precautions had to be taken to have efficient coverings 
for every instrument and to Reach the small com- 
pounds in which each instrument was enclosed. 
By April 20 arrangements were sufficiently 
advanced to warrant the commencement of rehearsals, 
and on six days before the eclipse these rehe arsals 
took place (Fig. 2). 
During the period occupied in preparing the instru- 
sea- 
