BISHOP'S RING AROUND THE SUN. 467 



record of parhelia for twenty-five years, confirms this opinion. "VVe 

 may, therefore, safely accept the conclusion that the change of color 

 from the blue of the open sky to the intense glare of whitish light 

 close around the sun, was until lately effected without the appearance 

 of any reddish tinge in the transitional area. 



The new corona, to which the name of " Bishop's ring " has been 

 given after its first observer, has never been a very conspicuous affair, 

 and therefore has not attracted the popular attention that it deserves ; 

 but it could easily be seen every clear day last winter, and has repeat- 

 edly been noticed since then in the latter months of 1885. The hazy 

 days of summer are not favorable to its visibility. It is best seen 

 from elevated stations, which gain their sky-colors chiefly from the 

 finer particles floating at great altitudes, as they are above the lower 

 strata of the atmosphere where the relatively coarse, haze-making dust 

 is suspended. Forel, of Morges, one of the most acute observers of 

 terrestrial physics in Switzerland, reports the distinct visibility of the 

 ring from mountain-tops, while it is not to be seen from the valleys, 

 where the whitish, hazy light overpowers its delicate colors. He adds 

 that many of his countrymen in the higher Alps had been struck with 

 the appearance of the new color in the sky before they had heard men- 

 tion of it. For the same reason Tissandier found the distinctness of 

 the corona greatly increased when viewed from a balloon high above 

 the dusty air of Paris. At low-level stations it is best seen during the 

 persistence of that type of weather known as " anti-cyclonic " among 

 modern meteorologists. Such weather is characterized by high baro- 

 metric pressure, and consequently has descending currents of pure, 

 clean upper air. The sky is then brilliantly clear and free from haze, 

 and at such times last winter the ring was of remarkable distinctness. 

 Thin cirrus clouds generally hide it ; but the presence of scattered, 

 sharp-edged cumulus clouds adds to its visibility in the clear spaces 

 between them. Let one of them stand before the sun, so that its 

 heavy shadow darkens the lower air, whose reflecting particles ordi- 

 narily add much white light to the blue of the sky ; then, looking be- 

 tween the clouds in the neighborhood of the sun, a broad arc of the 

 ring appears with its colors blending in what may be fairly called the 

 most delicate intensity. Just before a moderate thunder-storm early 

 last June, the ring was thus presented with most beautiful effect. 

 It was seen in Cambridge with extraordinary distinctness on the after- 

 noon of November 2, 1885, when the lower clouds of a heavy rain- 

 storm rapidly broke away in the west, about two o'clock, leaving the 

 sun well hidden behind a sheet of upper cloud and a space of open sky 

 below it. The lower air was thus well shaded from direct sunlight, 

 and the strength of the colors was most remarkable. There was first 

 the margin of the glowing central area at the edge of the cloud, soon 

 turning pale brassy yellow, and then strong reddish gold at about fif- 

 teen to twenty degrees from the sun ; farther out yet was the delicate 



