•v. NATURE OP THE DESTROYING BLAST.
THE facts connected with the Pelée eruptions of 1902, whether of May 8, May 20, or August 30, make it all b u t certain t h a t the engine of destruction was in all cases an explosion (or a series of rapidly following explosions), under enormous pressure, of superheated steam. A titanic blast of high temperature, carrying in its train the fragmented and incandescent particles of lava and the disrupted walls of the old stock of the volcano, swept out of the crater-spot of the É t a n g Sec, and fell with incredible fury upon the doomed city of SaintPierre, annihilating it almost instantly. In how far inflammable or asphyxiat ing gases m a y have been associated in the composition of this tornadic steam blast will perhaps never be known; the evidence which assumes their nonpresence is in the main of a negative character and hardly conclusive in itself to determine the problem. A large part, or perhaps even the major part, of the destruction wrought seems to have been accomplished in a few seconds. M. Roger Arnoux, of the Société Astronomique de France, apparently a very careful observer, who from the heights of his property a t Parnasse closely followed the workings of Pelée at the time of its explosion, asserts t h a t the destroying cloud traversed the city of Saint-Pierre in 2 - 3 seconds,* an observation t h a t finds con firmation in the accounts of the catastrophe t h a t have been published b y Chief Officer Scott of the Roraima and other eye-witnesses of the incidents of the fatal May 8. This extraordinary tornadic blast, whose explosive work was reg istered alike on hillside and in lowland, and whose sector of destruction was measured at the sea-front on a chord of 4 - 5 miles, was followed a t a short inter val b y the great down-rolling " b l a c k cloud," charged with incandescent m a t t e r ("fire"), and scintillating with electric flashes, which forms p a r t of the picture of nearly all of the descriptions, and to which is generally attributed the de struction. There is much in the history of this destruction t h a t still remains obscure, b u t I believe there can no longer be any doubt t h a t the work of the " black cloud" (the nuée dense, nuée ardente of Lacroix of later eruptions) was succes sive to and only secondary to the explosive work of the steam blast. The tornadic force of this explosive blast is attested b y the dislodgement from its pedestal of the massive statue of " O u r L a d y of the W a t c h " and b y the breaking clean across (like clay-pipe stems), near their bases, of the masts of the Roraima. I n an article published in McClure's Magazine for August, 1902, I expressed the opinion t h a t the destroying element of the blast was seem* L e t t e r addressed t o Camille F l a m m a r i o n a n d published in t h e Bulletin Astronomique de France, August, 1902. 60
de la Société