December 29, 192 1] 



NATURE 



571 



li^ht is reflected into them by means of a clock- 

 work-driven plane mirror called a " siderostat " 

 or "coelostat." Unfortunately such mirrors, 

 owing to changes of temperature, do not remain 

 "plane," but become slightly curved, thus ren- 

 dering it very difficult to keep the telescope in 

 perfect focus. Pointing the telescope directly at 

 the sun and keeping it clock-driven on an equa- 

 toriallv mounted stand eliminates all such diffi- 

 culties. 



Numerous photographs of the stellar field in 

 which the sun will lie at the time of the eclipse 

 have already been secured to compare with those 

 that will be taken during totality. The ex- 

 pedition will reside six months in the island pre- 

 vious to the eclipse, and will, in addition to other 

 work, make a comparison between the photo- 

 graphic scales of stellar magnitude in the north 

 and south hemispheres. Even if the eclipse be 

 not observed owing to possible bad weather, sdme 

 very useful work will have been accomplished. 

 The Christmas Island Phosphate Company will 

 assist the observers by levelling the site, erecting 

 the concrete base for the equatorial, and putting 

 up the necessarv huts, thus rendering valuable 

 assistance in the cause of astronomy. An 

 expedition from Batavia, in Java, will also 

 take up its station on this island. Mr. 

 J. G. \'oute will be the leader, and the party 

 may possibly camp near the Greenwich 

 observers to take advantage of the available 

 local assistance. 



The region on the north-west coast of Aus- 

 tralia, where the shadow next strikes land, known 

 as Ninety Mile Beach, is perhaps the most favour- 

 able station from the point of view of weather. 

 This area of the continent is excessively dry, and 

 the percentage of cloudiness small. The sun's 

 altitude will be 58° and the duration of totality will 

 be comparatively long, namely, 5m. i8s., at a 

 post station named W'ollal. Wollal lies about 

 200 miles to the south-westward along the coast 

 from Broome. Commercial steamers run from 

 Perth to Broome, and at the latter place local 

 small schooners or launches can be chartered to 

 beach near Wollal. Prof. A. D. Ross and Mr. 

 R. D. Thomson, of the Perth University, have 

 published (Monthlv Notices, R.A.S., vol. 31, No. 3) 

 a large amount of useful local information about 

 Wollal. Good water, fuel, and unskilled labour 

 are available. 



It is definitely known that a party of astrono- 

 mers from the Lick Observatory in California, 

 under the direction of Prof. W. W. Campbell, the 

 director of the observatory, will take up their 

 station there, and it is hoped that an Australian 

 party will occupy a position on the west coast in 

 addition to one or more on the east. The work 

 of the American party will probably include in its 

 programme the photography of the corona, and 

 spectroscopic investigation of the chromosphere. 

 In South-Eastern Queensland the shadow passes 

 consecutively over Cunnamalla, Goondewindi. 



NO. 2722, VOL. 108] 



Stanthorpe, and Casino. The first of these lies well 

 inland to the south of Queensland, about 475 miles 

 from the coast, and totality lasts 3m. 45s. This 

 station is more difficult of access than the other 

 three, but lies on the Western Railway of 

 Queensland. 



Goondewindi and Stanthorpe, 180 and 100 

 miles respectively from the coast, lie just to the 

 north-west of the New England range, and the 

 railway is also available. Casino, to the north- 

 east of the range, and only thirty miles from the 

 coast, is on the railway, and therefore quite easy 

 to occupy. The nearer the coast is approached 

 the more chance there is of unfavourable weather 

 conditions, so the most distant inland station, 

 Cunnamalla, is from this point of view the pick 

 of these stations. 



Mr, W. E. Cooke, the Government astronomer 

 of New South Wales, has published a pamphlet, 

 which is full of detail, of local notes on the selec- 

 tion of sites in Australia, and the large-scale map 

 of the Queensland region which accompanies it 

 should prove \^xy useful. Mr. H. A. Hunt, the 

 Commonwealth meteorologist, has also issued a 

 weather card showing the duration of the wet 

 seasons on the line of totality. 



The Australians are very keen that British 

 astronomers should take up their stations on 

 their continent, for at a public meeting held 

 recently at Adelaide under the presidency of the 

 Governor, a resolution was adopted inviting 

 British astronomers to view the eclipse there. 

 It was urged that Australia was superior to 

 Christmas Island because of the clear sky, par- 

 ticularly in the high northern district. 



While reference has been made only to official 

 expeditions which will be taking advantage of this 

 favourable eclipse, there will no doubt be other 

 parties which will proceed to one or other of the 

 above-mentioned localities. The sun itself will 

 most probably be in a state of quiescence, judging 

 from the recent low activity of the solar atmo- 

 sphere, and from the fact that the last maximum 

 of spot disturbances occurred in the year 191 7. 

 Thus the form of the corona will most probably 

 be of the " windvane " type, in which the coronal 

 streamers are restricted to the lower solar lati- 

 tudes, while the regions of both poles will be con- 

 spicuous by tlie presence of the well-known polar 

 rifts. 



It is well known that some eclipses are termed 

 " dark " or " bright," according to the visibility 

 of the distant landscape, near objects, or the face 

 of a watch held in the hand. Owing to the low 

 state of solar activity and to the long duration of 

 totality, next year's eclipse would be expected to 

 be of a " dark " nature. If this be so, then the 

 coming event will be more favourable for photo- 

 graphing those stars that are apparently near the 

 sun than was the case on the last occasion, when 

 such successful photographs were secured for 

 making one of the tests connected with the theory 

 of Einstein. 



