42 o The National Geographic Magazine 



The Smoke from the Top Crater rising 

 on May 30 to a Height of Six Miles 



Drawn by George Varian. Republished from 

 McClure's Magazine 



which boils out of the volcano in huge 

 rounded masses, swelling and evolving 

 in immense convolutions as it rises — one 

 gigantic mud bubble breaking up out of 

 another in turn — until over the crater 

 there stands a solid opaque pillar of boil- 

 ing, unfolding, evolving mud-vapor five 

 hundred feet in diameter and eight or 

 ten thousand feet in height." 



When such a debris-charged steam 

 column rises from a crater there is no 

 question as to the presence of a conduit 

 leading down deep into the earth. The 

 pseudo-craters seem never to reach such 

 intensity. 



"4. The vapor of great eruptions: 

 a straight-sided shaft of very black smoke 



(dust-charged steam) , which shoots up 

 out of the crater with a tremendous 

 velocity, like the smoke of a colossal 

 piece of artillery fired heavenward. This 

 shaft goes to a height of fifteen or twent y 

 thousand feet, and then mushrooms out 

 laterally, so as to cover a circle fifty 

 miles or more in diameter, with a vol- 

 canic canopy which is as dark as the 

 blackest thunder cloud and which shuts 

 out the light of day like a total eclipse. 

 The projectile force in eruptions of this 

 kind is so great that it throws the black 

 vapor far above the influence of the 

 trade winds, and the advancing edge of 

 the volcanic mantle moves swiftly east- 

 ward two miles or more above the fleecy 

 trade-wind clouds that are drifting in 

 the opposite direction." 



In the making of such a column as 

 just described the volume of water and 

 of comminuted rock required is enor- 

 mous. The volume of the column is 

 in the neighborhood of four billion 

 cubic feet. 



If 1 per cent of the column is solid 

 matter it equals 40,000,000 cubic feet, 

 equals 3,000,000 tons. 



If 10 per cent of the column is solid 

 matter it equals 400,000,000 cubic feet, 

 equals 30,000,000 tons. 



To be sure, we have no accurate meas- 

 ures, our information being almost en- 

 tirely qualitative ; but as such a column 

 as is referred to has been observed to 

 reach a height by estimate of 10,000 

 feet in two minutes, it may seemingly be 

 safely assumed that it reached its full 

 development in less than five minutes. 

 The coarser of the solid matter first shot 

 out then begins to fall, and the form of 

 the column is maintained by new matter 

 driven upward from the crater. Thus 

 during each five minutes of an eruption 

 some 4,000,000,000 cubic feet of debris- 

 laden steam were expelled from the cra- 

 ter. The average duration of such 

 eruptions is not known, but in certain 

 instances continued for several hours. 

 During; each hour that Mont Pelee or 



