212 



NATURE 



[April 14, 192 1 



time, is reproduced by kind permission of the 

 Astronomer Royal. The second exposure on the 

 plate was made in order to render a greater length 

 of the reference wires visible ; it was found very 

 difficult to orientate the plates of the 191 2 eclipse, 



Fig. 1. — Partial solar eclipse one minute after greatest phase. 

 Reproduced by permission of the Astronomer Royal. 



owing to the small amount of the wires that was 

 registered. 



It is curious that the writers of many of the 

 popular accounts of the eclipse speak of it as the 

 only large eclipse visible in London in the last 

 forty years, in forgetfulness of the still larger 

 €clipse of 191 2, for which also the weather con- 

 ditions were, favourable. 



Mr. Elborn, one of the assistants in the Botany 

 School at Cambridge, has made some interest- 

 ing observations on the behaviour of leaves during the 

 eclipse on April 8. 



It is well known that the stoma ta (which are minute 

 apertures in the leaves) are open in daylight and shut 

 in darkness. These facts are demonstrable by means 

 of a little instrument called the Horn hygroscope 

 described in my paper "Observations on Stomata " 

 (Phil. Trans.. B, vol. cxc, 1898, pp. 531-621). It will 

 1)6 seen that as the eclipse came on the readings fell 

 from 3-5 at S.40 a.m. to 15 at 9.38— that is, the stomata 

 closed considerably — and by 11.45 ^•"^- <^hey had re- 

 turned to their original condition, as shown by the 

 reading of the hygroscope, viz. 34. 



The plant used for the experiment was the common 

 Tropaeolum ; the behaviour of its leaves is shown in 

 the following table, the second column giving the 

 readings of the Horn hygroscope : 



A.M. 



8-40 3-5 



9- 5 3-2 



9.19 2-4 



9.21 2-3 



9.27 1-9 



9-32 17 



9-3^ 1-5 



A.M. 



9-So 



10. 4 

 10.20 

 10.34 



11. I 

 11-45 



1-5 

 17 



2-0 



2-8 



30 



3-4 



Francis Darwin. 

 Brookthorpe, Gloucester, April 11. 



The partial annular eclipse of the sun was well 

 seen in a clear sky in Herefordshire (N. lat. 51° 56', 

 W. long. 2° 38'). The darkening of the landscape 

 was marked, and the sky in the north assumed a 

 dark purplish-blue colour. It was not dark enough 

 to show any planets or stars even with field-glasses. 

 Birds continued to feed and hop about as usual. 



The most remarkable effect observed during the 

 darkest phase was on the sky surrounding the sun. 

 The atmosphere was slightly hazy from the east 

 wind, and on the sky, from the sun as a centre, was 

 projected a radiating series of narrow light and dark 

 rays visible for quite 20° from the sun. It was a 

 pretty phenomenon, and one which I had not ob- 

 served before. Eleonora Armitage. 



Dadnor, Herefordshire, April 8. 



During the maximum phase of the eclipse on 

 April 8 the shadows thrown by trees on a footpath 

 had a strange appearance, the details of boughs and 

 twigs being broken up more or less completely into 

 parallel crescents. At first sight the appearance sug- 

 gested a modification of the dappled effect of sunlight 

 falling through trees in summer ; but the shadows of 

 bare twigs were broken up in the same way, and such 

 scanty foliage as the trees bore was far too thin to 

 give rise to ordinary pin-hole images. Moreover, quite 

 detached shadows were affected. The shadow of a 

 narrow window-bar thrown on a floor was tagged out 

 at each side so as to look like the shadow of a ragged 

 feather from a pheasant's tail, 



E. Leonard Gill. 



Hancock Museum, Newcastle-upon-Tyne, 

 April 9. 



Obituary. 



Prof. S. W. Burnham. 

 pROF. S. W. BURNHAM, whose death is 

 -^ announced, was born on December 12, 

 1838, at Thatford, Vermont, U.S.A. His early 

 profession was that of journalist and stenographer 

 at Chicago. Burnham was, however, soon filled 

 with a zeal for astronomical research, in particular 

 double-star observation, in which department he 

 was one of the greatest and most successful 

 workers of all time. In 1870 he became the pos- 

 sessor of an excellent 6-in. refractor by Alvan 

 Clark. In spite of his arduous professional work, 

 he observed with this instrument nightly " till day- 

 light drove him to bed." He discovered 451 pairs 

 with it, nearly all difficult, and some of special 

 interest, being" faint, close companions of naked- 

 eye stars (for example, v Scorpii, mags. 4 and 8, 

 NO. 2685, VOL. 107] 



dist. 0-3''). Burnham had a marvellously acute 

 eye, some of the pairs discovered with the 6-in. 

 taxing the powers of the largest telescopes to 

 separate. His next work was done with the 

 i8J-in. refractor of the Dearborn Observatory, 

 Chicago, from 1877 to 1879; with this he dis- 

 covered 413 pairs, many of which are recorded in 

 vol. xliv. of Memoirs of the Royal Astronomical 

 Society. 



Burnham was selected in 1879, on Prof. New- 

 comb's recommendation, as Prof. Holden's col- 

 league for testing the atmospheric conditions at 

 Mount Hamilton preparatory to the founding of 

 the Lick Observatory. He remained there to 

 observe the transit of Mercury in 1881, and was 

 afterwards on the staff of the Lick Observatory, 

 making still further discoveries and observations, 



