January 23, 1903.] 



SCIENCE. 



151 



until recently. I first noticed it on the after- 

 noon of December 28 about half an hour 

 before sunset, when it formed a purple ring, 

 or partial ring around the sun, with the maxi- 

 mvmi color about 30° from the sun. The fol- 

 lowing note, made on January 9, gives a de- 

 scription as well as I can of the ring as it 

 appears at present. 



January 9- — At 9 to 10 a.ji. yesterday morn- 

 ing and again at 10 a.m to-day the ring 

 around the sun resembling a faint Bishop's 

 ring was visible. [Bishop's ring was the 

 name given to the ring observed around the 

 sun after the Krakatoa explosion in 1883.] 

 At 10 A.M. a whitish glare surrounded the sun 

 out to about 20°, when it showed a ring of 

 slightly yellow light ; outside of this, at a dis- 

 tance of 25° to 30° from the sun, was a ring 

 of faint smoky red or purple light visible out 

 to a distance of about 40° from the sun. 

 From 11 A.M. to 2 p.m. the colors were not 

 visible, but only the whitish glare. At 3 p.m. 

 a faint red or purple again became visible 

 on the outer edge of the glare and grew more 

 distinct as sunset approached. At 4:27 p.m., 

 about two minutes before sunset^ the glow 

 seemed to form a broad purple ring about 7° 

 wide and with its maximum intensity about 

 40° from the sun. At this time, and for sev- 

 eral minutes after sunset, the matter causing 

 the glare was visible as whitish strise within 

 the purple circle, resembling thin cirro-stratus 

 clouds or cirrus haze. The strise or ripples 

 extended in a north and south direction. 

 [Observations with a nephoscope on the two 

 succeeding days showed that they were mov- 

 ing very slowly from WSW.] Outside this 

 circle of glare around the • sun the sky was 

 blue all day without a sign of clouds. After 

 sunset the colored ring became a deeper 

 purple and approached the horizon. At 

 4:45 P.M. the maximum color was about 

 25° altitude and there was a fine purple twi- 

 light arch in the east. At 4:50 p.ji. there 

 was an orange glow on the horizon about 5° 

 wide, as there had been since sunset, and above 

 this was the greenish-yellow ring of striated 

 cloud matter, while above this latter was the 

 outer ring now developed into a bright pur- 

 ple afterglow, extending from about 10° to 



25° altitude. At 4:56 the afterglow had partly 

 merged with the glow on the horizon, forming 

 a bright orange glow extending to an altitude 

 of about 13°. After this time the outer edge 

 of the glow gradually approached the horizon, 

 and there was more red in the color. At 

 5 :10 P.M. the glow was about 4° broad and a 

 faint purple tertiary glow was visible with a 

 maximum of brightness at an altitude of 

 about 20°. At 5 :15 p.m. this glow was 

 brighter, with a maximum about 15°, while 

 the glow on the horizon was becoming fainter. 

 At 5 :20 p.m. the tertiary glow was still visible 

 with a maximum about 10°. After this the 

 color in both glows waned, and all color dis- 

 appeared from the western horizon about 5 :37 



P.M. 



The sunsets are less brilliant now than they 

 were in November and December, when they 

 reached their greatest brilliancy. On the 

 clearest days during these months the sunset 

 color lasted from an hour and twenty to an 

 hour and thirty minutes after sunset. The 

 maximum brightness and duration was some- 

 where near the first of December. The suc- 

 cession of colors in the sunsets on clear days 

 has been as follows : (1) An orange glow on 

 the horizon imrdediately following sunset, last- 

 ing twenty to thirty minutes ; (2) a purple 

 arch which appeared a few minutes after sun- 

 set high up in the sky, with its maximum 

 brightness 30° to 45° above the horizon. As 

 this glow approached the horizon it Increased 

 very much in brightness and Ijecame more 

 red, usually reaching its maximum brightness 

 about 25 minutes after sunset at an altitude of 

 10° to 15°, but sometimes continuing to in- 

 crease in brightness until it reached the hori- 

 zon, about 35 minutes after sunset; (3) a 

 second faint purple glow which appeared about 

 40 minutes after sunset between 20° and 50° 

 altitude, and reached the maximum brightness 

 about 50 to 55 minutes after sunset at an 

 altitude between 10° and 20°. 



The following note made on December 6, 

 1902, is typical of the observed changes. 



Decemler 6- — 4:12 p.m., sunset; 4:20 p.m., 

 orange glow on horizon, faint purple glow 

 over most of the western sky down to about 

 15° of the horizon; 4:25 p.m., bright yellow-red. 



