January 5, 191 1] 



NATURE 



319 



!it gas mantles now employed give an excellent light 

 uch appreciated by passengers, and gas commends itself 



the companies on account of but little skilled attention 

 ing required. Points which might be considered are a 

 lire generous use of steel in the body of the coach, and 

 ' adoption of fire-proof paint, as on the District Rail- 

 av. Extinguishers and a few fireman's tools might be 

 ovided in ev;ery guard's van. Lastly, it might be asked 

 lether it is not possible to reduce the chances of tele- 

 oping? It is only natural that the two front coaches of 

 ; ? train in question should be crushed ; they were situated 

 tween two engines and a sleeping-car weighing about 



tons. A uniform weight for passenger-carrying vehicles 

 ould appear to be a point worthy of attention. 



OLi? ASTEOSOMICAL COLUMN. 



Discovery of an Eighth-magnitude Nova. — A telegram 

 ■m the Kiel Centralstelle announces that a new star 

 as discovered by Mr. Espin, at Tow-Law, on December 

 , igio. Measurements were made at yh. 35-9m. G.M.T., 

 d the position of the nova is given as 



R..\.=22h. 32m. 9-5S., dec. =52° 15' 21* N. 

 This is just circumpolar in our latitudes, and, as the 

 object is at present of the eighth magnitude, numerous 

 observations should be possible, weather permitting. 



This object will be known as Nova Lacertae, as it lies 



in that constellation, forming the apex — to the north-east 



— of an approximately equilateral triangle, of which the 



base is the line joining a and /3 Lacertae ; it lies in the 



southern border of the Milky Way in that region. As 



' acerta transits during the afternoon, observations should 



possible during the greater part of the evening, and as 



^r. Espin records " bright lines," spectroscopic observa- 



■ns are desirable wherever possible. 



Later reports state that the star is red, and that bright 

 Hum and hydrogen lines have been seen in the spectrum, 

 lotographs of the nova were taken at Greenwich on 

 -cember 31, and the magnitude w'as reported as 7-5. 



Metcalf's Comet, 19106. — A continuation of Dr. Ebell's 

 liemeris for comet 1910b appears in No. 4462 of the 

 troiiomische Nachrichten. The present position of the 

 met lies in Corona at i5h. 52m., -1-36° 45-4', and is 

 jving northwards and slightly towards the west ; the 

 agnitude is nearly constant at 120. Although not very 

 .vourably placed for observation, the comet may still be 

 served during the hours of the early morning. 



Elements for Faye's Comet, igioe. — From observa- 



■ins made on November ii, 18, and 25, Prof. Risten- 

 part and Dr. Prager have calculated new elements for 

 comet igioe, and now publish them in No. 4462 of the 



'stroHomische Nachrichten. These elements confirm the 

 rntity of the comet with Faye's comet, and give the time 



i perihelion passage as 1910 October 30-04 G.M.T. ; the 

 eccentricity of the orbit is given as 0-5x69, and the comet's 

 period as 596 years. 



.\ set of elliptic elements, calculated by Mr. Meyer and 

 Miss Lev\', of the Berkeley Astronomical Department, and 

 published in No. 186 of the Lick Observatory Bulletins, 

 gives the time of perihelion passage as 1910 November 

 12-413 G.^LT., the eccentricity as 0-5459, ^^^ ^he period 



~ 6-926 years. 



-\ New Map of the Moon. — A map of the moon, pre- 



ired by Mr. Goodacre, was exhibited during last session 



the Royal Astronomical Society, and was enthusiastic- 



!y received by the selenographers present. Mr. Goodacre 



'w proposes to have the map reproduced on such a scale 



at the lunar diameter will be 60 inches, and to issue it 



the form of twenty-five separate charts, each 13 inches 



4uare. If 200 subscribers are forthcoming this can be 



done at the price of 22s. 6d. per set. The map shows all 



the known lunar features, their accurate delineation 



pending upon the positions of 1433 points given in Mr. 



;under's memoir (the Observatory, No. 429). 



The Total Eclipse of the Moon, November 16, iqio. 

 — RepK)rts of the observations made at a number of Con- 



NO. 2149, VOL. 85] 



tinental observatories during the total lunar eclipse which 

 took place on November 16 appear in No. 4460 of the 

 Astronomische Nachrichten. 



Dr. Max Wolf gives the times of entry and exit of 

 various features as recorded by a number of observers at 

 Heidelberg ; detailed observations of the various colorations 

 of different features are also reported. 



Father Fenyi, at Kalocsa, also records colours and re- 

 marks on the general brightness of the eclipsed surface ;. 

 at i2h. 33m. 12-37S. G.M.T. he observed the occultatioa 

 of the star B.D.-(-i8° 489. 



Occultations and colour variations are also recorded by 

 Herr Miindler, Prof. Kiistner, and Dr. Courvoisier. 



Nineteen Stars with Newly Discovered \'ariable 

 Radial Velocities. — In a paper appearing in vol. xxxii.. 

 No. 4, of the Astrophysical Journal, Mr. O. J. Lee gives 

 the measures of the spectra of nineteen stars which have 

 recently proved to be spectroscopic binaries. The spectra 

 were photographed at the Yerkes Observatory, the dis- 

 persion of one prism being usually employed. The stars 

 are «r Andromedae, t Cassiopeiae, p Tauri, v and ^ 

 Geminorum, 42 Camelopardalis, 7 Cancri, Hydrae, 

 <r Leonis, 23 Comae Berenices, t} and y Coronae, j and ir 

 Serpentis, y Ophiuchi, <j> Sagittarii, 13 Vulpeculae, 

 16 Lacertae, and a Pegasi. 



The multiple character of some of these stars was 

 announced by Prof. Frost and Mr. Lee at the Cambridge 

 meeting of the Astronomical and .Astrophysical Society in 

 -August, but t Cassiopeiae, y Ophiuchi, and a Pegasi are 

 now included for the first time. Some of these binaries- 

 are members of visual multiple systems, and in others 

 the examination of the H and K lines suggests that the 

 stars may belong to that class of binaries in which the 

 calcium lines appear to have a constant velocity. 



Observations of Planets. — The December (1910) 

 number of the Bulletin de la Societe astronomiaue de 

 France contains some interesting notes, by M. J. Halley,. 

 on observations of Venus made at Roubaix during 1909—10. 



M. Halley used a Secretan refractor of 135 mm. aper- 

 ture, and was favoured with excellent atmospheric con- 

 ditions. He records, in addition to the bright polar areas, 

 several markings which persisted during his observations ;; 

 the chief of these is a pair of dark streaks, divided by a 

 bright lane, running from the terminator towards the 

 south ; a dark patch, which appeared to lengthen, in the 

 northern hemisphere near the bright limb ; and a dark 

 area bordering the bright area at the north pole. 



Several of the photographs of Saturn exhibited by Prof. 

 Lowell are reproduced to illustrate a paper on planetary 

 photc^raphy which appears in the November (1910) number 

 of the Bulletin. 



COLOUR CONTRAST IN PHOTOMICRO^ 

 GRAPHY. 



'T'HE latest of the series of booklets issued from the 

 -*• laboratory of Messrs. Wratten and Wainwright,, 

 Ltd., Croydon, deals with photomicrography. This 

 booklet differs from most of the more pretentious works 

 dealing with photomicrography in that but little attention 

 is paid to the instrumental side of the subject, which is 

 dismissed with only a few words of practical advice, 

 attention being concentrated upon the relation between 

 colour and contrast, especially from the point of view 

 of the photography of stained sections. 



A perusal of most books on photomicrography indicates 

 that the more difficult parts of the subject technically, 

 such as the high-power photography of diatoms or minute 

 bacteria, receive a somewhat undue amount of attention 

 compared with their importance to the average worker in 

 science, the difficulties which less expert workers find in 

 obtaining really first-rate photographs of sections or pre- 

 parations being somewhat apt to be overlooked. The 

 greatest difficulty found is usually that the contrast 

 between the structure to be examined and the background' 

 is insufficient, and the main control of contrast is supplied 

 by the colour of the light used for illumination. 



A coloured object is, of course, coloured by virtue of 

 the propert)- w-hich it possesses of absorbing some of the 

 constituents from white light ; if the light reflected from 



