January 19, 1899] 



NATURE 



279 



trations of pictures taken by some of the more well-known photo- 

 graphers, and many other subjects too numerous to mention, but 

 which are of practical use to the amateur. Great pains have 

 apparently been taken to ensure the successful reproductions of 

 the pictures included in the 370 pages which compose this 

 volume, and a perusal of even these alone may give hints to 

 many amateurs on the somewhat difficult tasks of lighting, 

 pose, &c. 



The additions to the Zoological Society's Gardens during the 

 past week include a Gazelle [Gazella donas, 9 ) from Egypt, pre- 

 sented by Mr. J. S. N. Allison ; a White-cheeked Hill Par- 

 tridge (Arboricola atrigitlaris) from the Naga Hills, Assam, 

 presented by Mr. K. S. Cassells ; a Regent Bird (Serii iihis 

 iiiclinus, i ) from Australia, a Weka Rail (Ocydrotniis atistralis) 

 from New Zealand, a Black-headed Lemur (Lumiir brtinncus), 

 tired in the Gardens, deposited ; two Gluttons {Culo luscus, i 9 ) 

 from Northern, Kurope, a Common Otter (Lutra vulgaris), 

 British ; three Aiistralian Rails [Rallus pectoralis), two White- 

 <:heeked Honey-eaters [Meliphaga scricea) from Australia, a 

 Red Ground Dove (Geoliygoii niontaiia) from South America, 

 purchased. 



OUR ASTRONOMICAL COLUMN. 



Comet Chase. — This comet, which is now about as bright 

 as it was at the time of its discovery last year, has the following 

 ephemeris for the current week : — 



Berlin Alidyiigkt. 



Velocity i.v the Line ok Sight of tj Pegasi.— In a 

 previous number of the Astrop/iysical yournal{vo\. viii. No. 3), 

 Prof. Campbell pointed out that his observations had indicated 

 that the motion in the line of sight of the star t) Pegasi (R.A. 

 22h. 38-2m., Dec. -l-29'4i'-2, mag. 3-1) is variable. Writing 

 in the Astronomische Naihrichteii (No. 3536), Herr Belopolsky 

 tells us that he is able to corroborate this statement from observ- 

 ations made by him at the Pulkova Observatory. The following 

 ai-e the results of his measures of this star, the number in the 

 last two columns representing the velocities per second in geo- 

 graphical miles, in relation to the earth and sun respectively. 



The mean of Belopolsky's values for the two years thus re- 

 duce to -4'8 and -f i6"9 kilometres per second, while those of 

 Campbell for 1S97 July-September and 1898 August-Septem- 

 ber, are given as -4"-3and -f i6-2 kilometres per second. These 

 values it will be noticed agree well with one another, and 

 indicate further the accuracy that can now be obtained in such 

 measures. 



The Leonids in 1898.— In the December number of the 

 Monthly Notices there are several communications on the 

 meteors seen in November last, to which we have not yet drawn 

 our readers' attention. At the Cape Observatory, Dr. Gill had 

 made special provision for obtaining both eye observations and 

 photographs on the nights of the 13th and 14th. 



For the latter work, five cameras were arranged to cover the 

 region round the radiant point, while a Cooke doublet was 

 directed towards the radiant. All the cameras were fixed to 

 equatorials, and the plates changed every hour. No photo- 

 graphic results were obtained, and, indeed, the eye observations 

 indicated that the shower was nothing out of the ordinary. No 

 more fortunate was Dr. Copeland, who, with some assistants, 

 NO. 1525. VOL. 59I 



watched on the nights of the 13th to 15th. .\t Cambridge, Mr. 

 Hinks, who with several other observers kept their vigil during 

 the same three evenings until dawn, and were perhaps a little 

 more fortunate on the 14th, when from iih. to l8h. thirty-two 

 Leonids were seen. 



The shower seems, however, to have been better seen in 

 America, as will be gathered from the following extracts of a 

 letter from Prof. Barnard to Dr. Johnstone Stoney. Prof. 

 Barnard watched on the nights of the Iith-i6th, between the 

 hours 5 p.m. -6 a. m. 



He writes : — "The sky cleared shortly after midnight on the 

 14th. I soon saw there were a few meteors, but not noticeable, 

 which could be traced back to the radiant, though they were 

 mostly low in the north-west, near a Cygni. They became more 

 frequent, and some large ones were seen. From this till day- 

 light several hundreds were seen— many of the first magnitude, 

 and a few brighter. Very few were seen near the radiant, and 

 none at it." As regards the time of greatest frequency of the 

 meteors, Prof. Barnard says : — " It seemed to me the maximum 

 was reached between 3 and 4 a.m., perhaps nearer 4. It was 

 the finest display of meteors I have yet seen." 



On the i6th and 17th, not a single Leonid was observed by 

 Prof. Barnard. Five cameras were employed to record the 

 trails, but the development of the least promising of them has 

 given no trails. . 



New Instrument for Measuring Astrografhic 

 Plates. — Now that photography is so largely used for obtain- 

 ing charts of the stars, several styles of measuring instruments 

 have been devised to obtain directly the coordinates of the star 

 discs from the negatives. The great difficulty in designing 

 such instruments is that simplicity of construction, accuracy of 

 measurement, and rapidity of working must be well combined. 

 The most recent form is that which we owe to Dr. Gill, and 

 which will be found fully described and illustrated in the 

 Monthly Notices of the R.A.S. (vol. lix. No 2). While taking 

 advantage of the rapidity of Prof. Turner's method, Dr. Gill 

 has retained the accuracy which is attainable with the filar 

 micrometer. The result, as Dr. Gill states, has fully realised 

 his expectations, " thanks to the artistic skill and care of 

 ■Messrs. Repsold, to whom I entrusted the carrying out of my 

 plans.'' The whole process of measurement is "so simple 

 that an observer without any previous knowledge or experience 

 in practical work of the kind can, after very short training, 

 easily measure the two coordinates of eighty stars per hour 

 (including diameters) ; and were it not that the observers are 

 instructed to work very carefully, a larger number could be 

 measured in the same time." 



THE SPECTRUM OF THE CORONA} 

 T^HE announcement by Prof. Nasini of the possible presence 

 of the characteristic green line of the corona in the spec- 

 trum of the gases collected at the Solfatara of Pozzuoli (Nature, 

 vol. Iviii. p. 269, July 21, 1S98) renders it desirable that I 

 should at once publish some of the results of an investigation 

 relating to the spectrum of the corona with which I have lately 

 been occupied. 



In the course of my early observations of the spectrum of the 

 chromosphere, I discovered on June 6, 1S69, a bright line at 

 1474 on Kirchhoff's scale, which I stated to be coincident with 

 a line of iron {Koy. Soc. Proc, vol. iS, p. 76). 



During the total eclipse of the sun on August 7, 1869, a green 

 line was recognised by Prof. Young as belonging to the spectrum 

 of the corona, and the position of this line was also stated to be 

 1474K, 



Although other determinations of the position of the green 

 line of the corona during eclipses have not all agreed absolutely 

 with Young's observations, the differences have been attri- 

 buted to errors of observation, so that Young's statement of the 

 coincidence of the coronal and chromospheric lines, and their 

 correspondence with the solar dark line at 1474K has been 

 generally accepted. No special attention appears to have been 

 directed of late years to the measurement of the corona line 

 itself. 



This and other coronal radiations were photographed as rings 

 by the use of prismatic cameras in 1893, 1896, and 1898, but a 

 full list of them has only so far been published for the photo- 



' Paper read before the Royal Society 

 Lockyer, K.C.B., F.R.S. 



r 24, by Sir Norman 



