THE ERUPTION OF PELEE. 231 



Following such reasoning further, we find: (1) A rending explosion 

 raises some very coarse and heavy material, (2) this material falls 

 soonest and nearest the crater, (3) such falling material would have 

 very high velocity, but would come very quickly to rest on cone 

 slopes of 17°. Its fall would certainly deflect upward discharges of 

 lesser intensity, and its rush down the mountain with such deflected 

 vomitings would have the aspect of an avalanche, sending forward an 

 avalanche blast capable of short-lived but very fierce destruction. A 

 defiected discharge from the crater would be propelled by the same 

 force as the up-blast, and thus become both an avalanche and a down- 

 blast with tbe energy of the volcano behind it. It seems probable 

 that such a deflected mass of incandescent gravel and bowlders formed 

 the avalanche seen by Anderson and Flett. On this hypothesis, both 

 gravity and deep-seated explosion contribute to the tornado violence 

 of the black cloud, and the displacement of the air before the avalanche 

 resembles that frequently seen in high mountain districts, where snow- 

 slips project an air blast capable of leveling forests. Such snow-slides 

 have a tendency to hug the slope, to move very rapidly above and to 

 come to rest quickly below, and such movement was noticed in the 

 eruption which destroyed St. Pierre and in the eruption of Bandai- 

 san. In the latter also, the discharge changed from upward to hori- 

 zontal, the change being gradual as the upper air became overcharged 

 with solid matter. The other eruptions of Pelee and Soufriere showed 

 the same general characters, and that, of July 9 may be taken as an 

 example of an eruption of first magnitude. Its direction was more 

 to the westward than on May 8, hence the escape of Carbet and St. 

 Pierre. The materials ejected in the fiery avalanche were believed by 

 Anderson and Flett to be the products of exploded molten lava, which 

 welled over the lip of the crater and was blown to shreds by expansion 

 of gases. This view I can not accept, for I have as yet seen no glass 

 fibers or sherds, nor any evidence of new molten lavas in any way con- 

 nected with these eruptions. The angular bits of andesite and coarser 

 rocks found on the mountain after eruption are pieces of country-rock. 

 In some cases 'bombs' have been formed from old andesites with half- 

 molten surfaces. All the evidence so far goes to show that these 

 volcanoes are great steam crushers, comminuting and distributing 

 ancient volcanic materials. 



In conclusion, I wish to record my admiration of the excellent 

 work done by the Royal Society's commission, recalling with pleasure 

 association with Dr. Anderson and Dr. Flett in Barbados and Martin- 

 ique. Their memoir is by far the most thorough and scientific work 

 that has been published as yet on the West Indian eruptions. y^Cf^ 



