METEOROLOGY. 385 



He gives a comparison with the eruptions of May, 1783, in Iceland ; 

 July, 1831, in Sicily; Cotopaxi, in 185G; Vesuvius, 1862, and Kraka- 

 toa, 1883. In all of these cases similar twilight colors have been fol- 

 lowed by heavy rains. {Nature^ xxx, p. 229.) 



398. Mr. J. Murray communicates to the Eoyal Society, Edinburgh, 

 an extensive paper on volcanic ashes and cosmic dust, showing, among 

 other things, that in proportion as ashes are collected at a greater dis- 

 tance from a volcano, so are they less rich in minerals, while the pro- 

 portion of vitreous matter more and more predominates. {Naturey 

 XXTX, p. 585.) 



399. [In 1884 the twilightphenomena of 1883 were renewed, beginning 

 in England about September 10, and Berlin, September 13, Vancouver's 

 Island, September 30, while the records in England for 1883 were about 

 September 20. The maximum brightness in 1883 was about the 20th 

 of December, in 1884 it was later, but in general was decidedly infe- 

 rior and shorter than in 1883-'84.] 



400. M. Coruu maintains before the Paris Academy of Sciences 

 that the white or reddish tinted cloud-like nebulous halo or corona 

 that has permanently accompanied the sun during the whole of 1884, 

 and of which he gives many observations, i^robably has some connec- 

 tion with the Krakatoa eruption. That in fact a cloud of i)articles, 

 with a nearly uniform average diameter, was projected by the volcano, 

 and is held in suspension in the higher region of our atmosphere. 

 (IVature, xxx, p. 55G.) 



401. This cloud has been observed in Dublin since November, 1883. 

 [Nature, xxx, }). 663.) [It has also been observed in Washington since 

 about that date, with a j^eculiar streaky appearance, visible before sunset, 

 the lines being inclined to the west horizon, at an angle of about 30° 

 slanting down toward the south. The pink or purple tint has been 

 especially visible during the whole of any fair day. When the sun is 

 behind a cloud, and the observer examines the tints by sky between 

 the clouds, the purple is traceable for 30 to 40 degrees from the sun.] 



402. According to A. Griitzmacher, in Das Wetter for April, 1884, 

 and Koppen, in the D. M. Z., this brownish red ring about the sun ap- 

 pears to have first been observed in Europe at the end of November 

 1883, and not to have existed earlier. It is essentially different from 

 ordinary solar halos, and the material from which it comes must exist 

 beyond the highest cirrus clouds. Its explanation as a diffraction 

 phenomenon is undoubtedly correctly given by Kiessling. [D. M. Z., r, 

 p. 250.) 



403. O. Jesse, of Steglitz, near Berlin, has endeavored to compute the 

 altitude of the layer of dust or mist that has hypothetically caused the 

 twilight phenomena of 1883-'84. After fully explaining his theoretical 

 formula he applies it to observations made by himself on eight days at 

 Steglitz, from which he concludes an altitude of 17 kilometers, The 



S. Mis. 33 25 



