November 24, 1898J 



NA TURE 



83 



067? ASTRONOMICAL COLUMN. 



The Andromedes. — As regards the return of the Andromedes, 

 there is every reason to believe that by this time the shower 

 will have passed by the earth's orbit. Brilliant displays were 

 observed in 1872 and 18S5, on November 27 in each year ; and 

 it would naturally be inferred that on the same day of the 

 present year, which corresponds to an equal interval of time, 

 a like occurrence should taUe place In 1892, however, the 

 earth passed through this stream on November 23, and it has 

 been computed that this recession of the node was caused by 

 the perturbations of Jupiter, which were responsible for this 

 difference of four days." If the observations made on the 23rd 

 have indicated that this date is somewhat too early, observers 

 should be careful to watch on the following nights, for, after all, 

 the e.xact time of reappearance cannot be definitely foretold. 

 The radiant point of this shower is in Andromeda (25° + 43"), 

 and, therefore, at this time of the year at a great altitude. 

 Unlike the Leonids they move slowly, as they have to overtake 

 the earth in her movement round the sun. 



A close watch on the night of the 22nd was kept at the Solar 



Physics Observatory, South Kensington : but the usual fog made 



its appearance at about 9 p.m., and became thicker towards 



■ midnight. Altogether three meteors were seen between 8.30 p.m. 



and 12.15 a.m., but none of these were Andromedes. 



The Planet Jumter. — The markings on Jupiter, which are 

 involved in the dense atmosphere around him, have been 

 subjected to minute observations for many years, and it is now 

 that we are beginning to learn something of the circulation in 

 operation on that planet. That the atmosphere does not rotate 

 homogeneously has for many years been known, and the move- 

 ment of the great red spot may be given as an instance of this 

 irregularity. Mr. Stanley Williams, a faithful observer of 

 Jupiter, showed clearly in 1888 that there existed a swift southern 

 current which extended from latitude - 37° to - 55'. In a 

 more recent communication {Asli\ Nach., No. 352S) he has 

 published the results of observations of two southern spots 

 within this zone which were visible, one in 1890 and the other 

 two years later. The object of these observations was to 

 investigate whether such a current is a permanent feature of the 

 planet or not, and to trace from year to year the variations that 

 may occur in the %-elocity of its motion. 



Without entering into the details which are given in his article, 

 we will limit ourselves simply to his results. The following 

 table shows the periods of rotation obtained, the first being an 

 observation by I'rof. C. A. Young in 1886 of a small white spot 

 in latitude 50° south. 



A glance at the figures in the last column shows that this 

 southern current is not only a permanent feature of the planet, 

 but that its velocity is not constant. As regards the limit of the 

 zone in which this current exists, we are told that the current 

 may extend further southwards, and perhaps even to the pole 

 itself. 



We hope that Mr. Stanley Williams will continue his observ- 

 ations in this region, and settle this question of limit, which is 

 important in the light of the general atmospheric circulation of 

 this planet. 



The Perseids ok 1898. — In August last the weather was so 

 favourable that at a great number of places observations of the 

 Perseids were successfully made. A not unimportant feature of 

 the display was the large number of meteors that did not radiate 

 from Perseus at all, and this fact is very clearly brought out in 

 the description and chart of the observations made by Messrs. 

 Vacca and Senouque on the nights of the loth to the i6th 

 (Bull. Sot. Astroiioiiiiqiie de France for November). It must 

 be mentioned that at Paris, where these observations were made, 

 the night of the loth was not very clear ; so the majority of the 

 observations were made on the following nights. 



An examination of the diagram shows several distinct radiant 

 points, not only in Perseus, but in Cassiopeia, Cygnus, and the 

 Great Bear. 



Another set of interesting observations, made by M. Fournier, 

 is published in the same journal, and contains also a repro- 



NO. 15 17, VOL. 59] 



duction of a chart, showing the trails recorded. This, how- 

 ever, is restricted to the night of the loth, which was beautifully- 

 clear at the place of observation, and the chief radiant point 

 deduced is well defined near tj Persei. Out of sixty meteors 

 observed, thirty-nine were Perseids, five or six sporadic, andi 

 some others apparently radiating from Cassiopeia. 



Astronomical Society of Wales. — The last two monthly 

 numbers of this Society's publication, the Cambrian Natural 

 Oisen'er, show that interest in astronomical phenomena is by 

 no means at a low ebb, but rather verging on a spring tide. 

 The October number contains some interesting notes about 

 Gruithuisen, who was for some time editor of the yahrlnich. 

 His great speciality was a study of the lunar features ; and 

 although ridiculed, he was nevertheless "an assiduous and care- 

 ful observer. " Mr. Denning contributes some notes on meteoric 

 fireballs, and describes how observations should be recorded. 

 He gives, also, the right and the wrong way of recording them, 

 or rather, we should say, the useful and the useless, from 

 published examples, and we cannot help quoting thein as 

 guides to future recorders. 



"On June 10, 1891, I saw a beautiful phenomenon. Sud- 

 denly at the zenith, east of the Great Bear, shone forth a 

 yellow globe like Venus at her brightest. Dropping, somewhat 

 slowly, it fell obliquely southwards. As it passed in its brilliant 

 career, it lighted up its dusky path with a glorious lustre. 

 When it had descended about half-way down towards the 

 horizon, it burst into a sparkling host of glorious fragments, 

 each dazzlingly shot over with all the hues of the rair>bow." 



The useful record was as follows : — 



Date and time. — 1892 December 12, lih. 22m. G.M.T. 



Object. — Fine meteor, nearly = Jupiter. 



Path. — 55° + 41' to 45° + 20° ; length 22°. 



Duration of flight. — i '2 seconds. 



Colour. — Bluish- white. 



Appearance. — Brightest in latter portion of its ijath, where 

 it left a white streak for about one second. 



Probable radiant. — e Ursae Majoris. 



The November number is especially a " meteor " number, 

 and contains information on the observation of these bodies by 

 Denning, Johnstone Stoney, Carslake Thoinpson, cStc. 



Photographic Plates and the Spectrum. — In labor- 

 atories and observatories where a study is made of gaseous and 

 metallic spectra by the aid of photography, it is important to- 

 make use of the differences between the sensitiveness of the 

 numerous photographic plates which are obtainable. For that 

 particular part of the spectrum which may be under investiga- 

 tion, it is always desirable to employ the greatest photographic 

 action possible, and this can only be done by preparing plates 

 which are most sensitive to this region. A very interesting 

 comparison of the sensitiveness of various plates for the different 

 regions in the spectrum is given by Mr. E. Sanger Shepherd 

 [Journal of the Camera Club, vol. xii. No. 150), in an article 

 on the photographic reproduction of paintings ; and curves are 

 added, showing clearly how each of the plates behave. 



Comparing the Cadet spectrum plate and the Ilford chro- 

 matic plate, the former gives action beyond the I) line, whereas 

 the latter ceases at the D line ; there is very little red sensitive- 

 ness, which is perhaps the worst feature of the plate, and there 

 is a gap in the green. Luniiere's panchromatic plate has ex- 

 treme red sensitiveness ; but except for a small gap, in the greet> 

 it is sensitive all through the spectrum. In Lumiere's " B "^ 

 plate the sensitiveness in the red is very considerable and more 

 extensive than in the plate preceding, but there is a very long 

 gap in the green. Edward's snap-shot isochromatic plates have 

 considerable sensitiveness in the green and yellow, and a little 

 less in the red ; the curve is here much smoother, and not 

 subject to such great changes. 



In the Cadet lightning spectrum plate we have extreme sensi- 

 tiveness from the blue to the yellow, and yet sufficient red 

 sensitiveness for many purposes. Considering the whole spec- 

 trum, it seems to be the best plate for uniformity throughout, 

 and the small gap in the extreme red makes it possible to use a 

 considerable amount of light for developing. 



Although it is not absolutely necessary, it is always more con- 

 venient to develop in a room lighted sufficiently to see how the 

 image appears. Many photographers do not pay sufficient at- 

 tention to the purity and colour of light that is admitted. "The 

 gaps in the sensitive curves point out clearly those rays which 

 have least action on the plate, and which should therefore be 



