THE
ERUPTION
OF
PELÉE
19
lisk in its earlier period. The phenomena attending the growth of the dome were those of the general eruptions: the evolution of the great volcanic steamash cloud, rising a t times to 2000, 3000, and 4000 metres above the summit of the volcano; loud detonations, frequent discharges of dust and boulders, and the more violent explosions of the " b l a c k cloud." During the eruption of September 9, which lowered the dome 15 metres, the nuée dense, following the course of the Rivière Blanche, reached the sea in five minutes, thus repeating the history of the early period of Pelée's activity. I n an earlier eruption,September 3, when the dome lost 30 metres, a similar cloud reached the sea in seven minutes. I t is significant t h a t a t about the middle of September these clouds, instead of following the usual downward course, now in the main ascended vertically.* On September 15-16 such a cloud rose to the extraordinary height of 7000 metres. During much of the period here noted p a r t s of the dome appeared brilliantly incandescent, some of the luminous points being fixed for a number of consecutive days. On a few nights when observations were permitted, nearly the entire surface of the dome appeared as if in a glow of fire, and brilliant reflections were thrown upon the clouds overhead. The trains of boulders discharged from the dome with almost every violent eruption were also frequently incandescently luminous. I t would seem t h a t b y the first of October the new dome had actually been constructed to a height slightly exceeding 500 feet, doubtless enclosing within itself a considerable portion of the lower moiety of the destroyed obelisk, if, indeed, it did not again bring it to a condition of molten fluidity. The most rapid development of this extraordinary structure appears to have been on August 30-31, when, as reported by M. Giraud, the rise in a single day was 78 feet (24 metres).† I t is interesting to note in connection with the construction of this remarkable crateral dome t h a t it was accompanied b y new extrusions of solid " t u r reted" matter, acicular processes or obelisks appearing at different times in two or more p a r t s of its summit. Thus, in the early days of September, 1903, the observers of the French Scientific Commission noted t h a t the dome terminated in an aiguille rising from its northwest part, which needle on September 7 rose nearly 10 feet. On September 9 this new growth acquired an additional 6 metres, and between September 10 and 12 further 8 metres. A second process was at a later day extruded through the southeast portion of the dome, and its fortune, as well as t h a t of the earlier one, partook of the same vicissitudes of construction and destruction which marked the history of the original great obelisk. On October 20 it lost 5 metres. There seems to be at this time no way of ascertaining the precise relations existing between these newer structures and t h e basal portion of the first formed and partially buried obelisk; nor can * Giraud, " La C o l o n i c " See also t h e n u m e r o u s d a t a given in Lacroix's final report, " L a Montagne Pelée et ses É r u p t i o n s , " 1904, p p . 138-150. †La Colonic