48
THE
ERUPTION
OF
PELÉE
Jahre 1903," in Mitteil. d. Naturfor. Gesell. in Bern (1904) 1905, pp. 7 et seq — (1903) 1904, pp. 1 et seq. Zi-ka-Wei, China. Sept. 15-16 (De Moidrey, Ann. de la Soc. Météor. de France, L, 1902, p. 220). The characteristics of the Pelée (and Soufrière) afterglows were similar to those of the glows of Krakatao, although the intensity of the coloring and illumination was probably a t most points of observation less pronounced t h a n in the case of the glows of 1883 and 1884. As I observed the coloring towards the middle of September, at localities north-northwest of Martinique, a few days after the fresh great eruptions of Pelée and the Soufrière, it was very brilliant, the orange and the red being particularly fine. The upper border of the bright illumination faded off into a superb and intense lilac, which, I believe, had not generally been observed as a feature of the K r a k a t a o glows. Bishop noticed this lilac color in 1884 in Honolulu, even in daytime, and it is certainly due to the commingling of the pink or roseate light with the normal blue of the sky. Five great "shadow-beams," with broadening ends directed to the zenith, and of almost exactly the color of the purple-blue in the outlying field of the sky, were a distinctive feature of the area of the glows on September 9 and 10, radiating fan-like from the position of the sun and rising to perhaps forty-five degrees. The brilliancy of the glows as they were observed in p a r t s of western Switzerland was such as to suggest a conflagration, appearing " a s if the whole of the west of Switzerland was on fire and the flames reflected in the sky."* I t is singular t h a t Professor Herschel makes the same observation for the appearance a t Slough, England, on the night of J u n e 22, which was " a n almost terrifying resemblance to reflection in the sky of an immense distant conflagration" (Nature, July 24, 1902, p. 294). I have been personally informed t h a t the same aspect of the glows was noted in Honolulu, where m a n y thought t h a t the islands were aflame. The height of the glow-producing m a t t e r has been estimated by Herschel to have been at different times from five or eight to thirteen or twenty miles, whereas the atmosphere charged with the volcanic dust of K r a k a t a o was thought to have floated twenty-five or thirty, and even forty and seventy miles high, the uppermost particles of m a t t e r being a t t h a t time much finer than those emitted by Pelée. I t is interesting to note in connection with the low position of this glowcloud, as compared with t h a t of the K r a k a t a o eruption, t h a t its velocity of passage was also greatly inferior. Bishop tells us t h a t it arrived in Honolulu ten days after the Pelée outbreak, whereas the K r a k a t a o glows, traversing thrice the distance, arrived a t the same spot in only two days' longer time. This would give in the one instance a velocity of about two and a half times t h a t of the other, or of sixty to seventy miles an hour in the case of the K r a k a t a o cloud, and of twentythree to twenty-five miles for the cloud from Pelée. There is seemingly no reason to doubt t h a t the movement was in both cases from east to west, * Correspondence in L o n d o n Daily Chronicle,
d a t e d Geneva, J u l y 14.