3o6 



NA TURE 



[January 25, 19C0 



OUR ASTRONOMICAL COLUMN. 



Densitv ok Close Double Stars.— Many authorities hold 

 the opinion that the mean density of close double stars is in 

 general low as compared with that of the sun. In the Astro- 

 physic ai Journal (\o\. X. pp. 308-318) there are two papers, by 

 Messrs. A. Roberts, of Lovedale, South Africa, and 11. N. 

 Russel, of Princeton, U.S.A., which examine mathematically 

 the possible limiting values of the densities of those double 

 stars constituting the Algol type of variables. The limiting 

 value for the mean density of the star is calculated from the 

 observed period and duration of light variation. The results 

 obtained independently by the two authors are, considering the 

 uncertainty with which many of the periods of variation are 

 known, fairly well in agreement. The general conclusion is 

 that these variables of the Algol type are probably more than 

 five or six times less dense than the sun. 



A New Photographic Photomeier. — Dr. J. Hartmann 

 describes in the Astrophysical Joiirnal (yo\. x. pp. 321-332) a 

 new photographic photometer he has devised for use at the 

 Potsdam Astrophysical Observatory, in the determination of 

 stellar and other magnitudes. The difficulties involved in 

 previous instruments — viz. distance between standard scale of 

 intensities and portion of plate to be measured, apparent alter- 

 ation of intensity owing to surrounding parts of plate — have 

 been eliminated by employing a broken microscope, the two 

 objectives of which feed a single eyepiece with the images of 

 the standard scale'and the portion of the plate under examina- 

 tion ; and, by arranging small apertures over both scale and 

 plate, practically all contrast effect is got rid of. The double 

 microscope enables the two regions to be optically in juxta- 

 position, so that the point of equalisation of intensity can be 

 found with great precision. 



A BRILLIANT METEOR IN SUNSHINE. 

 /^N Tuesday afternoon, January 9, at2h. 55m. p.m., when the 

 ^^ sun was shining brightly in a cloudless sky, a large meteor 

 was observed as a conspicuous object by many persons in the 

 south-eastern part of England. Moving in a direction from 

 west to east, it dashed rapidly across the southern sky and 

 finally terminated its career, as observed from several places in 

 Surrey and Kent, when situated under the moon, then in E. 

 by S., altitude about 33°. The rarity of a daylight fireball, and 

 the astonishing brilliancy it must exhibit to enable it to present 

 a striking aspect even in the presence of the sun, lends a special 

 interest to the phenomenon, and makes it desirable to collect 

 all the particulars concerning.it. 



I have seen about fifteen descriptions of the meteor, and they 

 nearly all emanate from the counties of Surrey, Kent and Sussex. 

 Three of these accounts have already been quoted in Nature 

 of January 18, and the remainder, in a summarised form, are as 

 follow : — 



Maida Vale, London, W. Time 2h. 59m. — Apparent course 

 of meteor due W. to E. First appeared in S.S.W., and dis- 

 appeared somewhat to the right of the moon. Track nearly 

 horizontal, about 25" altitude. Nucleus elliptical ; long tail ; 

 colour silvery ; no sparks or explosion. — J. G. Wood {Tt»ies). 



Warlingham, Surrey. Time about 2h. 30m. — A very con- 

 spicuous meteor passed from about S.W. to N.E., and vanished 

 almost under the then position of the moon. It was about 45° 

 from the horizon, and its line of movement curved downwards. 

 Colour very white, reminding one of burning magnesium wire. 

 It was rounded in front and tapering to a tail, leaving a few 

 sparks behind, but no cloud.— F. '&V.^\iM:\:'Y: {Ensilish Mechanic). 



Guildford, Surrey. Time 2h. SS^i- — The meteor was first 

 seen to the S. [? W.] of the moon, and two-thirds of the dis- 

 tance from the earth between the moon and the earth, and 

 moved downwards towards the N. , and vanished exactly under- 

 neath the moon. The lowest star of the three stars in Orion's 

 sword was as near as possible in the place where the meteor 

 vanished, at 5h. 45m. p.m. The head was very bright, pure 

 white, and appeared about 3 inches across. It left a faint«tail. 

 It went out and did not burst. — C. J. Careless. 



Earlsfield, S. IV. Time between 2h. 50m. and 3h. — A yellow 

 meteor shot from the right-hand side of the moon downwards, 

 disappearing under the moon. The duration was estimated 

 as between 3 and 4 seconds. — Correspondent of English 

 Mechanic. 



Beckenham, Kent. Time 2h. 55m. — A brilliant meteor passed 

 across the sky at about 60° above the horizon, and in a general 

 direction from a little to the N. of W. to the S. of E. The 

 rneteor was very distinct, and apparently of large size. It com- 

 prised a head and a brightly glowing body, which, as it travelled, 

 appeared to throw off flakes of flame. The meteor, leaving a 

 trail of bright light behind it, vanished, as it seemed, quite low 

 down.— Edward Kingshall {Daily Graphic). 



Fenshurit, Kent. Time 2h. 57m. — Brilliant meteor seen here 

 like a ball of burning zinc, emitting yellow sparks. Seemed to 

 move from S.W. to N.E. Vanished almost direct under moon. 

 Path appeared perfectly horizontal. The meteor broke up as it 

 travelled, fiagments flying from it much yellower than the mass 

 in front.— Thomas Parker [English Mechanic and letter to 

 W. F. D.). 



Dunstable. — The daylight-meteor was seen here by my grand- 

 son, aged 14, who says it fell almost vertically (?) from a N. or 

 slightly N.W. direction. It resembled a very large, brightly 

 luminous, white kite with a long tail. It seemed to fall straight 

 on to the houses of this town.— Worthington G. Smith 

 (letter to Nature). 



Eastbourne, Sussex. Time between 3h. and 3h. 30m.— A 

 very bright meteor rapidly traversed the sky from a little W. of 

 S. to a little N. of E. The transit was very rapid, and the 

 direction slightly curved downward ■;. I saw it from the front, 

 between the Wish Tower and Beechy Head, and it disappeared 

 over Hastings. It passed just below the moon. In spite of 

 the sunshine the meteor showed with an intense white brilliance. 

 The tail was long and feathered— H. E. S(,)UIRE fetter to 

 W. F. D ). 



Worthing, Sussex. Time between 3h. and 4h. — As I stood 

 facing E. I saw something fall like a rocket downwards, running 

 from S. to N. The head was large with a very long tail ; the 

 light was similar to electric light. 



Pyecoinbe, Sussex. Time 2h. 55m.— As my brother was on 

 his machine from Poynings, he noticed a meteor which appeared 

 to come from the moon, in the form of a ball of red and blue 

 fire, taking a course due northwards, and leaving a trail of light 

 behind it for some considerable time. — A. Reed [Sussex Daily 

 News). 



The meteor was also seen at Weybridge, Surrey, darting 

 towards the N. It resembled a huge diamond with a long 

 pointed tail. 



1 have been in correspondence with Mr. Bouverie, who saw 

 the meteor at Lewes, and with the Rev. R. Hudson, who 

 noticed it from Brighton (Nature, January 18). The former 

 says the meteor took a course from the lower side of the moon 

 at an oblique angle towards N.E. The observer at Brighton 

 says the first appearance was 5' or 7° below the moon, and the 

 path sloping downwards from S.E. to N. ; estimated track from 

 50° alt. when first seen to 30° at disappearance behind houses 

 in N. 



It was a very fortunate circumstance that the moon enabled 

 the place of the end point of the meteor to be correctly assigned. 

 But the descriptions are, as usual in such cases, somewhat dis- 

 cordant ; and the only alternative is to adopt a path which 

 approximately satisfies the observations. There is no doubt 

 that the meteor was descending, though not at a large angle, 

 and that the earliest portion of the flight was over the S.S.W., 

 as observed at Maida Vale and Eastbourne. Several observers 

 evidently did not notice the first part of the path, and thought 

 that the meteor commenced its visible flight from a place very 

 near to the moon. 



The radiant point was probably at a rather low altitude in 

 the S.W. sky. It could hardly have been farther south, as the 

 long path and rapid motion oppose such a view. Observations 

 from the N. coast of France would be very useful in settling the 

 question. , I have derived the following figures for the real path, 

 which may be regarded as provisional, and liable to revision if 

 further descriptions come to hand. 



Meteor began — 59 miles in height, over a point 10 miles 

 east of Valognes, near Cherbourg, France. 

 Meteor ended — 23 miles in height, over Calais, France. 

 Length of path — 175 miles. 

 Radiant point— 280°- 12°. 

 The actual velocity is doubtful. An observer at Reigate 

 Heath says the meteor " was visible for about a second," though 

 "it traversed a considerable portion of the heavens." At 

 Earlsfield, S.W., the duration was roughly estimated as 3 or 4 

 seconds. Several observers say it moved " rapidly." 



NO. 1578, VOL. 61] 



