i6 



NA TURE 



[November 6, 1902 



Henry Frowde at the price of one shilling net, should be 

 obtained by everyone interested in the history of science. 



In a communication published in the May number of the 

 Transactions of the American Microscopical Society, Messrs. 

 Whipple and Parker discuss the connection between the amounts 

 of oxygen and carbonic acid dissolved in natural waters and the 

 occurrence in these of microscopic organisms. It has long been 

 known that exhaustion of nitrates takes place in ground 

 water supporting a vigorous growth of alga?, and it has been 

 assumed that nitrates are the fundamental factor in the 

 development of these. Nitrates are indeed important, but the 

 inadequacy of this explanation became manifest when it was 

 observed that some water, comparatively poor in nitrates, at 

 times supported large growths of algx. The authors point out 

 the apparent importance of carbonic acid, and express the 

 opinion that the alga; are influenced by it more than by the 

 nitrates. The study of the number of organisms in water at 

 different depths has given some interesting results. Water 

 taken from Lake Cochituate was found to contain the following 

 numbers of Mallomonas per cubic centimetre : — 



Depth in feet ... o 10 30 30 40 50 

 No. of organisms o o 1454 548 112 88 



At the surface and throughout the circulating water above the 

 ihermocline, oxygen was abundant, but carbonic acid was absent. 

 Near the bottom of the lake there was carbonic acid, but no 

 oxygen, whereas just below the thermocline both gases were 

 present, and as Mallomonas is a chlorophyll-bearing organism it 

 fcund there ccnditions favourable for its development. 



The additions to the Zoological Society's Gardens during the 

 past week include two Kusimanses (Crossarchus obscurus), 

 a White-crested Tiger Bittern {Tigtiscma lettcolophum), a Great- 

 billed Touracou (Tin;!, us macrorhynchus), a Sharpe's Wood 

 Owl (Syrnium nuchale) from West Africa, presented by Mrs. 

 Hurst; a Mute Swan (Cygnus olor), a White-fronted Goose 

 (Anser albifrons), four Widgeon (Mareca penelope), two 

 Pintails (Dafila acuta), four Pochards (Fuligula ferina), six 

 Common Ducks (Anas boscas) European, two Black Swans 

 (Cygnus at rat us) from Australia, presented by Mr. W. N. 

 McMillan ; a Persian Gazelle (Gazella stibgutterosa) from 

 Central Asia, presented by Mr. B. T. Ffinch ; two Emperor 

 Boas (Boa imperator) from Central America, presented by 

 Dr. Hans Gadow, F.R.S.; a Thick-tailed Opossum (Didelphys 

 crassicaudatus) from La Plata, a Blue-fronted Amazon (Chrysotis 

 oestiva) from South America, deposited. 



OUR ASTRONOMICAL COLUMN. 



Variation in Magnitude of a Orionis. — Mr. D. E. 

 Packer, of Birmingham, has recorded, in a letter to No. 1961 

 of the English Mechanic, the observation that a Orionis is in- 

 creasing in brightness. Although a known variable, its general 

 vaiiations for the past thirty years have been so minute as to 

 attract no particular attention, but Mr. Packer says that, on the 

 night of October 15, the star was distinctly brighter than 

 Capella and only slightly less bright than Sirius. 



Herschel recorded very marked variations in the magnitude of 

 this star between 1836 and 1S40, and Sir W T . Huggins noticed 

 variations in its spectrum during a second period of variability, 

 1849-1852. Mr. J. E. Gore confirms Mr. Packer's observ- 

 ations. 



The Nebula around Nova Persei. — Prof. C. D. Perrine 

 publishes, in the Bulletin (23) of the Lick Observatory, several 

 reproductions, and the measures, of the excellent photographs of 

 the nebula around Nova Persei which were obtained with the 

 Crossley reflector, and he also discusses the striking changes 

 observed in the condensations of the nebula. 



From measurements of the negatives obtained on March 29, 

 1901, and January 10-11, 1902, respectively, it appears that the 

 inner ring of nebulosity is expanding radially, at an average rate of 



NO. J 723, VOL. 67] 



1 "'4 per day, whilst the outer ring is similarly expanding 2" '8 

 per day. These measurements of the inner ring would carry 

 it back to the Nova on February 8, 1901, whilst the outer ring 

 is similarly carried back on February 16-17 ; both the plates 

 give the same dates. This does not imply the prior formation of 

 the inner ring, for. considering the uncertainties of measurement, 

 Perrine suggests their contemporary origin. 



Many suggestions have been made to explain the apparent 

 velocities of parts of the nebula, the two chief explanations 

 being the transition of material particles, and the propagation of 

 a wave of light through, and reflection from, the fine particles 

 of matter making up the nebula. The former seems unlikely, 

 because the movement contains a large tangential factor, whilst 

 the latter theory would have to presume largely variant velo- 

 cities of the light waves, a presumption which is inconsistent 

 with our present knowledge of light. In order to test the 

 " reflection" theory, Prof. Perrine introduced a double-image 

 prism between the plane mirror of the Crossley reflector and the 

 photographic film, and found that the light was not polarised, 

 i.e. the two images were of equal intensity. On polarising the 

 light from a Lyra; and treating it in the same manner, he 

 found that the mirrors of the instrument had practically no 

 effect on polarised light. 



The final result points to the existence of little or no polar- 

 isation in the light from condensation D, and, with less 

 certainty, in that from condensation A, and therefore refutes ihe 

 reflection theory. 



Coronal Disturbance and Sun-Spots. — In No. 98 of 

 Popular Astronomy, Prof. Perrine demonstrates the close con- 

 nection between the coronal disturbance, photographed at 

 Sumatra during the total eclipse of 1901, and the group of sun- 

 spots and extensive faculce which came round the limb of the 

 sun on May 19. 



From photographs of the solar disc obtained at Dehra-Dun, 

 India, between May iS and 28, inclusive — of which copies were 

 kindly supplied to Prof. Perrine by the Astronomer Royal— it 

 is seen that a fairly large group of spots and facula? came round 

 the limb on May 19, and that at the time of the eclipse this 

 group would be very near to the limb. The position angle of 

 the spot, as projecled on to the limb, was 6o Q- 2, whilst that of 

 the apex of the coronal disturbance was 6o°o, and during the 

 eleven days under observation this was the only group of spots 

 photographed. This shows conclusively that the spot and the 

 coronal disturbance were in the same line of sight, and further 

 reductions have shown ihe probability that the origin of the 

 coronal disturbance was also near to the limb at the time. The 

 long, thread-like prominence seen projected almost tangentially 

 from the sun's limb during the eclipse appears to have emanated 

 from the same group of spots and faculae, so that, in this case 

 at least, all these phenomena appear to have had a common 

 origin. 



This aggregation of related phenomena seemed to point to 

 the possibility of the existence of a great disturbance in the 

 solar atmosphere on this date, and a further investigation was 

 made in order to discover Jf any measurable displacement of 

 the coronal masses took place in the disturbed region. The 

 photographs compared were taken at an interval of five 

 minutes, and no measurable displacement can, with certainty, be 

 traced thereon ; from this we may conclude that the velocity 

 across the line of sight was less than twenty miles per second. 

 A comparison between the photographs obtained at Mauritius 

 and Sumatra, respectively, with an interval of one-and-a-half 

 hours, would probably decide this question of movement. 



The Variable Star 13, 1902, Lyr.-e. — Further observations 

 of this Algol variable have given the following results : — 



Approximate position for 1900, I9h. 12m. 31s. +32° 14' "S. 

 Range of magnitudes, 1098 to about 128. Period, 3d. 14)1. 

 22m. 23s. '5. 



The Variable Star Committee of the Astronomische Gesell- 

 schaft has assigned to this star the designation R.V. Lyra; 

 (Astronomische Nachrichten, No. 3821). 



New Variable Star, 15,1902, Delphini. — Dr. Anderson, 

 of Edinburgh, has communicated to No. 3S21 of the Astro- 

 nomische Nachrichten his observation that a star, not men- 

 tioned in the B. D. , but having the approximate position R. A. = 

 2oh. 34m. 43s., Dec. = + 11° 2i' - 5 (iS55'o), has proved to be a 

 variable. 



Assigning the'magnitudes 9 "5, 9 7 and 1 1 - 2 toB. D. + 11° '4353 > 

 B.D. + ii°'435S, and a star having the approximate position 



