Page:Popular Science Monthly Volume 61.djvu/372

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POPULAR SCIENCE MONTHLY.

razed much that before had been upright, 'hot ashes were steaming at the water's edge, and there were immense bowlders lying in a bed of ashes.' These horizontal blasts are not hard to account for and do not

Fig. 16. St. Vincent: The Fatal Windward Slope of the Soufrière. Leaving the horses preparatory to the ascent. The mountains in the background in clouds. June 4, 1902.
Fig. 17. St. Vincent: Ascent of the Windward Slope of the Soufrière, showing the author and party, in a black fog, 2,700 feet up, the height of the western rim of the crater. An anxious moment. The high rim was shortly after reached, 3,200 feet up (on the right).

require a horizontal nozzle to project them. They are simply the result of the downblast after the heavy gravel has begun to fall, acting against the upblast from the throat of the volcano, and both together