862 
NATURE 
[June 23, 1923 

to 1450° C. (within the 6 range) and similarly cooled. | 
On examination, a striking difference in structure 
between the two was found, constituting evidence 
that there is a distinct change in crystal structure 
at the 5 to y transformation. This may be re- 
garded as a confirmation of Westgren’s conclu- 
The Indian Eclipse 
‘THE story of an expedition to observe the total 
eclipse of the sun, seen under the most perfect 
atmospheric conditions, but which failed to achieve 
any results, is described by Mr. Evershed in the report 
before us. Mr. Evershed’s programme was of a high- 
class order, and those who know him and his great 
ingenuity in the construction and manipulation of 
astronomical apparatus will share his regret at his 
extreme misfortune on this occasion. 
Originally Mr. Evershed proposed to occupy the 
Maldive Islands as his observing station, but, owing 
to difficulties of transportation, he and his party 
went to Wallal, near Broome, situated on the north- 
west coast of Australia, and joined Dr. Campbell’s 
expedition. For the Einstein effect he took out 
with him a 12-inch photo-visual lens particularly well 
adapted for this problem, giving, as he states, “a 
large field of good definition and a larger scale than 
the lenses used previously, or that would be likely 
to be used by other expeditions.” It was worked in 
conjunction with a 16-inch ccelostat, and it was the 
erratic behaviour of this instrument that spoilt the 
results. In spite of constructing a new tangent screw 
and refiguring the teeth of the driving sector to 
secure better driving qualities, the fifteen seconds 
~ exposure plates showed movement of the star images 
and poor definition of the corona due to the bad 
driving of the ccelostat. Two short exposure plates 
were badly fogged “‘ in some unexplained way ’’ over 
two-thirds of the surface, but otherwise the remaining 
portion showed the ends of the coronal streamers 
beautifully defined. 
The second main effort of the expedition was to 
photograph with large dispersion the spectrum of the 
corona on the east and west limbs simultaneously, in 
order to determine the displacement of the green 
corona line due to the solar rotation, and to secure a 
more accurate wave-length of this line. Here again 
disappointment was experienced, for the corona line 
did not appear at all on any of the plates owing, 
probably, to the unusual faintness of this radiation at 
this eclipse. Perhaps Mr. Evershed rather courted 
disaster on this occasion, as it is generally conceded 
that during the time at and near a minimum of solar 
activity this radiation is also near a minimum of 
brightness. 
1 Report of the Indian Eclipse Expedition to Wallal, Western Australia, 
by J. Evershed, F.R.S. (Kodaikanal Observatory, Bulletin No. 72.) 

Liberal Education in 
«* Saturday, June 9, a conference of educationists 
in Yorkshire was held in the University of 
Leeds under the presidency of the vice-chancellor, 
Sir Michael Sadler, in response to a widespread 
desire to discuss certain questions affecting the 
supply of full-time education for boys and _ girls 
beyond the age of eleven years, and the choice of 
subjects in the School Examinations. In order to 
make the conference widely representative of educa- 
tional opinion in Yorkshire, invitations were issued 
to the local education authorities, the universities, 
NO. 2799, VOL. IIT] 

sion, based on X-ray analysis, that 6 and y iron 
are constitutionally different. He found that the 
former has a body-centred and the latter a face- 
centred cubic lattice. B.C. Gas 
1 Journal of the Iron and Steel Institute, 1922, No. 1, p. 241, and Nature, 
June 24, 1922, p. 817, 
Expedition, 1922.1 
It will be remembered that the Greenwich expedi- 
tion to Christmas Island purposely eliminated the use 
of a ccelostat in its work by taking out a complete 
equatorial photographic telescope. This was done 
because experience at the eclipse of May 29, 1919, 
seemed to suggest that the definition of the star 
images on the astrographic plates was poor, owing 
probably to the distortion of the ccelostat mirror by 
the heat of the sun. Mr. Evershed’s view regarding 
the employment of a ccelostat is that it is “ good for 
the Einstein effect. For only with a ccelostat is it 
practically possible to get.an adequate scale.” That 
he is emphatic on the point is shown by his statement 
that ‘‘ the question of the ccelostat mirror introducing 
complications is, I think, a bogy. Plane mirrors 
can now be constructed of large size and perfect 
figure, and experience with mirrors, good and bad, 
has shown that little is to be feared from distortion 
of the surface when the silvering is fresh and good, 
and simple precautions are taken.”’ : 
In the opinion of the present writer, the great 
drawback to the use of a mirror during eclipses, 
whether mounted as a ccelostat or siderostat, is due 
to the change of figure of the plane surface of the 
mirror, which causes an alteration in the position of 
the focus of the object glass. On many occasions 
during eclipse expeditions, although extreme care 
had been taken to secure a “‘ perfect’’ focus on star 
spectra at night (the mirror then being comparatively 
cool), the focus was quite different for the solar 
spectrum during the daytime. Thus during eclipse 
work it was always found most necessary to watch very 
carefully the disappearing crescent of the sun on the 
ground glass almost right up to the time of totality, 
and if necessary alter the position of focus accordingly.” 
It is satisfactory to note that Mr. Evershed did not 
return to India with an empty bag. During a short 
stay at Broome on the return journey he set up the 
16-inch siderostat and 12-inch lens and succeeded in 
obtaining a good high dispersion spectrum of Canopus 
and Achernar to use in connexion with his work on 
the spectrum of Sirius. 
During this expedition Mr. Evershed was ably 
assisted by Mrs. Evershed and by Mr. Everson of the 
physics department of the University of Western 
Australia. WILLIAM J. S. LOCKYER. 
~ 
* See Phil. Trans. Roy. Soc. A, vol. 198, p. 406. 
Secondary Schools. 
the training colleges, secondary schools, associations 
of secondary and elementary teachers, and other 
persons of educational experience. Upwards of 270 
representatives attended the conference and were 
welcomed by the pro-chancellor, Mr. E. G. Arnold. 
In an introductory speech, the chairman referred 
to the growing desire for wider opportunities of a 
liberal education in various parts of the world. 
This desire cannot be wholly explained as due to 
self-regarding motives. Ambition for advancement 
is no doubt a strong motive, but is not in itself 
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