January 26, 1893] 



NATURE 



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Wt' a bbautiful optical phenomenon, which has not yet been 

 satisfactorily explained, is described by M. F. Folie in the 

 Bulletin of the Belgian Academy. It was observed about a 

 mile from Zermatt on August 13 at 8.30 a.m. " On our right, 

 towards the east, on the steep flanks of the mountains which 

 enclose the valley of the Vie^e, rose a group of fir trees, the 

 highest of which projected themselves against the azure of the 

 sky, at a height of 500 m. above the road. Whilst I was 

 botanising my son exclaimed : ' Come and look : the firs are 

 as if covered with hoar-frost ! ' We paid the most scrupulous 

 attention to the phenomenon. To make sure that we were not 

 misled by an illusion we made various observations, both with 

 the naked eye and with an excellent opera-glass." It was 

 observed that not only the distant trees, but those lining the 

 road, glittered in a silvery light, which seemed to belong to the 

 trees themselves, and that the insects and birds playing round 

 the branches were bathed in the same light, forming an aureole 

 round the tops of the trees, somewhat resembling the light effects 

 observed in the Blue Grotto. It is suggested that the light was 

 reflected from the snow. Since it disappeared as soon as the 

 sun rose above the hill, and has never been seen except in the 

 presence of snow, this explanation appears plausible, but it is 

 highly desirable that further and more detailed observations 

 hould be made of this spectacle feerique. 



The Tasmanian Official Record is henceforth to be issued 

 tri-annually instead of annually, and a handbook has been 

 issued to take its place during the intervening years. This hand- 

 book (which is described on the title-page as "for the year 

 1892") contains a brief epitome of the historical portion of the 

 Official Record, and summarises in a convenient form the more 

 important statistical inforoaation contained in the detailed tables 

 of the last volume of the general statistics of the colony. 



Messrs. Asher and Co. will publish shortly an English 

 translation of the " Recollections of the Life of the late Werner 

 von Siemens," the well-known electrician, and brother of Sir 

 ■\Villiam Siemens. Two editions of the German original, pub- 

 lished in December last, were issued in the course of a few 

 weeks. 



The course of four winter lectures in connection with the 

 London Geological Field Class will this year be delivered by 

 Prof. H. G. Seeley, F.R.S., on Tuesday evenings, at the 

 Memorial Hall, Farringdon Street, the subject being "The 

 Fossil Reptiles of the Thames Basin," All particulars may be 

 had of the Hon. Sec. Mr. J. H. Hodd, 30 and 31, Hatton Gar- 

 den, E.G. 



The bacterial purification which takes place in a river during 

 ^ its flow has been recently attributed in part to the process of 

 \ sedimentation which the micro-organisms in the water undergo, 

 ! but it would seem that yet another factor must be taken into 

 I account. Buchner, in some investigations which he has recently 

 published (" Ueber den Einfluss des Lichtes auf Bakterien," 

 Centralblatt fiir Baktcriologie, vol. il, 1892, also vol. 12, 

 p. 21 7) shows that this diminution of the numbers present may be 

 also assisted by the deleterious action which light exercises upon 

 certain micro-organisms. A systematic series of experiments 

 was made by introducing typhoid bacilli, B. coli communis, 

 B. pyocyaneus, Koch's cholera spirilla, also various putrefactive 

 bacteria, into vessels containing sterilized and non-sterilized 

 ordinary drinking water. As a control, in each experiment one 

 vessel thus infected was exposed to light, whilst a second was 

 kept under precisely similar conditions, with the exception of its 

 being covered up with black paper, by means of which every 

 particle of light was excluded. The uniform result obtained in 

 all these experiments was that light exercised a most powerful 

 bactericidal action upon the bacteria in the water under observa- 

 tion. For example, in one water in which at the commencement 

 of the experiment 100,000 germs oiB. coli communis were present 



NO. I 2 13, VOL. 47] 



in a c.c, after one hour's exposure to direct sunlight none were 

 discoverable, whilst in the darkened control flask during the same 

 period a slight increase in the numbers present had taken place. 

 Even the addition of culture fluid to the flasks exposed to sun- 

 light could not impair in the least the bactericidal properties of 

 the sun's rays. In the flasks exposed to diffused daylight the 

 action was less violent but still a marked diminution was ob- 

 served. In his later experiments Buchner has employed agar- 

 agar, mixing a large quantity of particular organisms, patho- 

 genic and others, with this material in shallow covered dishes and 

 then exposing them to the action of light an! noting its effect 

 upon the development of the colonies. For this purpose strips 

 of black paper cut in any shape (in the particular dish photo- 

 graphed by Buchner letters were used) were attached outside to 

 the bottom of the dish, which was then turned upwards and 

 exposed to direct sunlight for one to one and a half hours and 

 to diffused daylight for five hours. After this ths dish was in- 

 cubated in a dark cupboard. At the end of twenty-four hours 

 the form of the letters fastened to the bottooa of the dish was 

 sharply defined, the development of the colonies having taken 

 place in no part of the dish, except in those portions covered by 

 the black letters. Some interesting experiments on the same 

 subject have also recently been made by Kotljar {Centralblatt 

 fiir Baktcriologie, December 20, 1892). In the course of these 

 investigations the author found that of the coloured rays of the 

 spectrum the red favoured the growth of those bacteria experi- 

 mented with, whilst the violet rays acted prejudicially, although 

 less so thin the white rays. The exceedingly interesting obser- 

 vation was made that the violet rays actually favoured the sporu- 

 lation of the Bac. pseudo anthracis. 



The additions to the Zoological Society's Gardens during the 

 past week include a Macaque Monkey (Macacus cynomolgiis S ) 

 from India, presented by Mr. A. Sandbach ; a Triton Cockatoo 

 {Cacatua triton) from New Guinea, presented by Mr. Arthur 

 Harter ; a Gannet {Sula bassana) British, presented by Mr. F. 

 W. Ward ; two Tuatera Lizards {Sphenodon punctatus) from 

 New Zealand, presented by Mr. W, H. Purvis ; two Wanderoo 

 Monkeys {Macacus silenus) from the Malabar Coast ; a Straw- 

 necked Ibis {Carphibis spinicollis) Uom Australia; four Snow 

 Buntings {Plectrophanes nivalis) ; six Wild Ducks {Anas 

 boschas, 3 cJ 3 9 ) British, purchased ; a Meadow Bunting {Em- 

 beriza cia) European, received in exchange ; two Shaw's 

 Gerbilles {Gerbillus shaivi) born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Comet Y{oi.^e.s.— Edinburgh Circular, No. 37, announces 

 that Palisa, telegraphing from Vienna, states that Comet 

 Holmes now resembles an 8 m. star with a nebulous envelope 

 20" of arc in diameter. 



A further observation made by Prof. Schur in Gottingen on 

 January 19 showed that the nucleus was of the loth magnitude, 

 and could not be considered at all brighter than that magnitude. 

 For the latter observation the air, as regards clearness, was all 

 that could have been desired. 



At South Kensington, on January 18, the comet was observed 

 as a hazy star and estimated to be about the 8th magnitude. 



The following ephemeris is that given by Schulhof :— 

 Date. R.A. app. Decl. app. 



h. m. s. a I II 



Jan. 26 ... I 35 33° ••• + 33 42 3 



27 ••• 36 587 •■• 42 SI 



28 ... 38 25-1 ... 43 44 



29 ••• 39 52"i ••• 44 43 



30 ... 41 198 ... 45 46 



31 ... 42 48-1 ... 46 55 

 Feb. I ... 44 170 ... 48 8 



2 ... I 45 465 • • 33 49 26 

 On January 30 the comet will lie very nearlyjbelween j3 Andre- 

 medoe and /3 Trianguli, about one-third of the distance from the 

 latter star. 



