8-i 



KNOWLEDGE. 



[April, 1902. 



given moment, all the details of the planet's confipuration, 

 but only a very small fraction of them. A careful naked- 

 evo study of the full moon leads to the same impression. 



Durin'r; the lust apparition of Mars the Cerlierus was 

 fully as dark as the Mare Clmmerium. It was. moreover, 

 seen double at Juvisy, the duplication being independently 

 contirmed by two skilful English amateur observers, Mr. 

 Striven Bolton, of Leeds, and Mr. Eruest Attkins, of 

 Highgate (Fig. G). Another double canal was the Casius 

 in 1900-1901. 



A comparison of these drawings with Prof. Sebiaparelli's 

 charts contirms the accuracy of the Milan designs, though 

 departing from them iu many partieuhirs. Leaving aside 

 the absence of delicate shading in Schiaparelli's repre- 

 sentations of the planet's north hemisphere, which might 

 be of a physiological origin, we might readily attribute 

 the most striking discrei)aneies to actual change on the 

 Martian surface. As far as minor detail is concerned, the 

 planet is no longer what it appeared to be from 1877 to 

 1890, the chief changes during the last decade being : — 



(fl) The unaccountable disappearance of Aouius Sinus 

 since the 1892 opposition ; 



(6) The fading of the canal, once the darkest, Nilo- 

 syrtis ; 

 ' (c) The bridging of Syrtis Major by " Nili Pons " ; 



(d) The formation of the canal " Nasamon " ; 



(e) The great faintness of the Cerberus in 1894 (Fig (5), 

 and its extraordinary darkness during the apparitions of 

 1898-1899 and 1900-1901 ; 



(/) The increased darkness of the canals Amentlies 

 and Nilokeras ; and 



((/) The darkness of Phlegra, Cebrenia, /Etheria and 

 Utopia, together with the formation of the " Copais 

 Lacus." 



Some of these metamorphoses occurring, as they do, in 

 the equinoctial zone of Mars, are hard to ascribe to mere 

 seasonal change. Nor can it be argued that the changes 

 lie within observational errors. The possible occasional 

 formation of cloud cannot help us any better here, inasmuch 

 as the disappearance of dark markings (such as the Aonius 

 Sinus) is not attended by a corresponding whitening of 

 the regions in question. Clouds condensing on Mars 

 ought to appear as white spots, hence differently coloured 

 from the yellow continents, as well as from the grey 

 " Maria." And thus is it that the majority of changes 

 occurring oa this little planet will remain long, if not ever, 

 one of the greatest enigmas which it was given us to 

 witness in the universe. 



[The Editors do not hold tbemselveg responsible for the opinions 

 or statements of correspondents.] 



THE GREAT SUN-PILLAR OF MARCH G. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — A very fine example of the sun-pillar was visible 

 on Thursday, March tJth, at St. Leonards-on-Sea ; and as 

 the phenomenon is somewhat uncommon, a short descrip- 

 tion of it may be of interest to your readers. 



The day had been remarkably fine and clear for the 

 time of year, and towards evening the western horizon 

 became hazy. About ten minutes before sunset, a faint 

 red glow was noticeable above the sun's disc ; but it was 

 not until the sun had disappeared behind the dark outline 

 of the South Do\vns that the phenomenon became 

 strikingly beautiful. The sunset was a characteristic 



one ; small rod clouds standing out sharply against a 

 clear greenish-blue sky. By 6 o'clock the yellow pillar 

 had become very clearly defined ; it extended upwards for 

 a consiili'ra1)le distance from the horizon, ami was brightly 

 luminous thr()Ughout its entire length. As the sunset 

 colours deepened to i)urple and orauge, the band appeared 

 to increase in brilliancy. 



But the most remarkable feature of the phenomenon 

 was to follow, for the i)illar gradually changed in hue 

 from yellow to deep rose, as the sunset tints had previously 

 done. And finally it appeared like a gigantic ruby candle 

 flame, showing up brightly from behind a long grey 

 cloud-bank. It was still traceal)le at 6.25, or about forty 

 minutes after the sun had sot. 



Another sun-pillar was visible at St. Leonards one 

 evening last June, appearing as a bright ])erpendicular 

 beam of yellow light springing from the setting sun But 

 the iustanrr roonlrd nbove differed from it, Ijoth in the 

 gradu;iil\' iliT].riiln'4 lolours of the pillar, and also iu the 

 fact that till' pilhu- ilself was always of a different hue to 

 that of the background of sky on which it was projected. 

 Apart from its beauty, the phenomenon of March 6th was 

 so wonderfully distinct, and of such long duration, that 

 it must have attracted the attention of many observers. 



Any of )our readers who niay be interested iu the 

 formation of sun-pillars by horizontal reflection, will find 

 an explanation of the phenomenon in an illustrated article 

 by the Rev. S. Barber, on p. 132 of the Knowledge 

 Volume for 189.5. 



S. E. Stawell Brown, b.a. 



St. John's College, Oxford, 

 March 12th,''1902. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — Shortly after sunset last night my attention was 

 called to a remarkable sight. From the point uj)On the 

 horizon where the sun had disappeared, a glorious parallel- 

 sided shaft of brilliant rose-red light traced its length 

 (some 45° or more) upwards towards the zenith, ujion the 

 clear background of twilight sicy. 



From the fact that a belt of thin grey cloud veiled the 



Sun-spot of 1902, March 9. 



brilliance of a small section of it, it was evident that the 

 shaft was beyond and independent of the cloud. 



It was under constant observation from 5.55 p.m., when 

 it was first "timed," until it disappeared below the horizon 

 at 6.28 p.m. It sank all the while slowly and steadily 



