JuLv 9 1908] 



NA TURE 



Visual observations of three of the more prominent lines 

 in the yellow and green are also given : — 



A more detailed list of lines will be published later. We 

 understand that Sir William Ramsay showed a photograph 

 of the spectrum of the emanation at the meeting of the 

 Royal Society on June 25. It will be of interest to com- 

 pare the two spectra. E. Rutherford. 



T. RovDs. 



University, .Manchester, July 4. 



Tl.e Recent Nocturnal Glows. 



The peculiar light phenomenon at midnight on June 30, 

 which was seen, according to the papers, on the northern 

 part of tne sKy at Copenijageii, Koiiigsberg, Berlin, 

 \'ienna, Biala, and other places, was also observed by me 

 at Prague. At ih. 30m. a.m. on July i, I saw in the 

 direction X.E. and N.N.E. a peculiar strong orange-yellow 

 light over the horizon, the colour of which was more 

 orange in its lower parts and more yellow in its higher 

 parts. Its upper limit was lying twenty to thirty degrees 

 above the horizon. The whole sky was cloudless. Other 

 people saw it here at 11 p.m. on June 30. 



It is reported that magnetic disturbances were experi- 

 enced on the telegraphic lines, but I saw no trace of the 

 characteristic .auroral bands or columns. I may be allowed 

 to add that, according to .\rrhenius, this tiine of the year 

 corresponds to the minimum of auroral display (activity). 

 Interesting is the fact that a high barometric maximum 

 was lying in the north, and that we had winds from that 

 direction for a whole week. 



BOHUSLAV BRAUNER. 



Bohemian University, Prague, July 4. 



A Long-lived Solar Halo. 



There has been visible here to-day a solar halo remark- 

 able both for its vivid intensity and for its protracted 

 duration. It was first noticed by ine at 12.35 P-m. It 

 then formed an unbroken ring, of which the most intensely 

 luminous portion was to the south of the sun, and the least 

 luminous portion to the west-north-west. Half an hour 

 later the southern and northern quadrants of the circle 

 were equally bright, but the northern appeared the more 

 compact and definite ; meanw-hile, the eastern and western 

 portions continued comparatively feeble, more especially 

 the latter. Tlicse condilions rcDiaitifd unchanged for fully 

 ij hours! After 2.15 p.m. the northern segment of the 

 halo was alone conspicuous, and after 3.30 p.m. the ring 

 was never again complete, though two mock suns (to the 

 southward and eastward respectively) still testified to the 

 original configuration. By 4.50 p.m. nothing remained 

 but a diffused, pale rainbow-coloured mock-sun to the north 

 of the sun; but after 5.15 p.m. this became less indefinite, 

 :md by 6 p.m. fully a semicircle of a halo was again trace- 

 able above the sun, but this faded gradually, nothing 

 surviving after about 6.20 p.m. The unusually strong tone 

 of rusty orange colouring, and the conspicuous darkness 

 of the region enclosed, made the halo an unusually striking 

 object when at its best (12.30 to 2 p.m.). 



Throughout the day cirrus cloud has strewn the sky 

 in most intercsiing disorder and variety of fonns. Tele- 

 scopic observation of the sun's image showed (in the 

 features of atmospheric distortion of the sun's limb) the 

 existence of two distinct drifts of the atmosphere, viz. an 

 upper current, of great velocity, passing over from the 

 south-east above the drift from north-north-east that alone 

 affected the local weather-cocks and chimneys' smoke. I 

 may add that my experience as an observer of halos (both 

 solar and lunar) has led me to the conclusion that cirrus 

 clouds, or the conditions conducive to the formation of 

 cirrus cloud, do not in themselves constitute the whole 

 cause of the formation of halos, but that these are further 

 the outcome of cross-currents in the region of cirrus 

 formation. Catharine O. Stevens. 



10 Woodstock Road, Oxford, June 30. 



P.S. — Portions of solar halos were also seen here inter- 

 mittently during July i and 2, thus giving a record of 

 three successive davs of halo formation. 



Genial June. 



The month just past has fully upheld its character, as 

 it did in the Jubilee year, 1887, and on other occasions. 



There were a great number of dates suitable for observa- 

 tion (sixteen out of the last seventeen), but I found shoot- 

 ing stars rare. 



The nights before June 29 were, I thought, unusually 

 dark, the stars and Milky Way being beautifully bright 

 and distinct ; but on June 30 the firmament was abnormally 

 luminous, w-ith a very strong glow all over the north at 

 midnight. Few stars could be seen, and the .Milky Way 

 was hardly distinguishable. On July i the phenomena of 

 the previous night were repeated in rather a different aspect. 

 There were many clouds of various tints, and the light 

 was again intensely strong, the northern sky being in- 

 volved in a brilliant aurora. I have never seen June nights 

 so dark, and the Milky Way so gorgeously displayed in 

 the heavens, as this year to June 28, nor have I ever 

 noticed the sky so bright as it appeared on the nights of 

 June 30 and July i. 



The aurora offered so vivid a spectacle that on the dates 

 mentioned the shades of night may be said to have been 

 quite dispersed, for even at midnight the reflected light 

 from sky and cloud was so strong that terrestrial objects 

 could be seen just as at dusk, say at about 10 p.m. on an 

 ordinary June night. W. F. Denning. 



Bristol, July 2. 



THE DARMIN-W.ILLACE JUBILEE CELEBRA- 

 TION AT THE LINNEAN SOCIETY. 

 ON July I, 185S, Sir Charles Lyell and Dr. J. D. 

 Hooker communicated to the Linnean .Society a 

 remarkable paper entitled " On the Tendency 

 of Species to form Varieties ; and on the 

 Perpetuation of Varieties and Species by Natural 

 Means of Selection," by Mr. Charles Darwin and 

 Mr. .\lfred Wallace. The history of this paper is 

 familiar to every student of biolog-y. Darwin had 

 for many years been studying- the question of natural 

 selection and its bearing upon the origin of 

 species, but, although his views were w-ell known to 

 several intimate friends, he had refrained from pub- 

 lishing them, and was still occupied in the collection 

 of evidence when he received from ^^'alIace a manu- 

 script essay " On the Teiidencv of Varieties to Depart 

 indefinitely from the Original Type," in w-hich the 

 same ideas were set forth. -At the request of the 

 author this manuscript, after perusal, was forwarded 

 bv Darwin to Sir Charles Lyel!, with the added sug- 

 gestion that the essay should be published as soon a-; 

 possible. After consultation with Hooker, Darwin 

 was induced to allow an extract from his own work on 

 the subject to be published simultaneously. 



The reading of this joint paper at the Linnean 

 Society formed the starting point of a revolution in 

 scientific thought the effect of whicli it would 



NO. 2019, VOL. 78] 



