Page:Popular Science Monthly Volume 37.djvu/194

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THE POPULAR SCIENCE MONTHLY.

Herculaneum, and Stabiæ, in the year 79. The eruption of Krakatoa, in 1883, exceeded, in all probability, in its deadly effects, and as a wonderful phenomenon of nature, the outburst of Vesuvius in the year 79. It is shown, in the report of the Krakatoa Committee of the Royal Society, that the detonations caused by the explosive action were heard a hundred and fifty miles away. Captain Thompson, of the ship Medea, sailing at a point seventy-six miles northeast of Krakatoa, saw a black mass like smoke rising into the clouds to an altitude which was estimated as not less than seventeen miles. All the eye-witnesses agree as to the splendor of the electrical phenomena. The old crater of Krakatoa was eviscerated, and a cavity was formed more than a thousand feet deep. On the morning of the 27th of August three vessels at the eastern entrance of the Strait of Sunda encountered the fall of mingled dust and water, which soon darkened the air, and covered their decks and sails with a thick coating of mud. Some of the pieces of pumice falling on the Sir R. Sale were said to have been of the size of a pumpkin. All that day the three vessels were beating about in darkness, pumice-dust falling upon them in such quantities as to employ the crews for hours in shoveling it from the decks and in beating it from the sails and rigging. The speed and distance attained by the pumice ejected from the volcano may be conceived from the fact stated in Mr. Douglas Archibald's contribution to the report, that dust fell on September 8th more than thirty-seven hundred English miles from the seat of the eruption. The great mass of the pumice was of a dirty, grayish-white tint, and was very irregular in size.

The dust ejected from Krakatoa did not all fall back at the same time upon the sea and the earth. The lightest portion formed into a haze, which was as a rule propagated westward. Most observers agree in regarding this haze as the proximate cause of the twilight glows, colored suns, and large corona which were seen for a long time (more than two years) after the eruption. The haze was densest in the Indian Ocean and along the equatorial belt, and was often thick enough to hide the sun when within a few degrees of the horizon.

I hope I have succeeded in showing that infinitely small objects, no larger than particles of dust, act important parts in the physical phenomena of nature.

 


 
Mr. H. W. Seton-Karr tells, in one of his books of travels, of his ascent of one of the spurs of Mount St. Elias, following the track of a brown bear with always an uneasy expectation of meeting the animal itself, to the height of seven thousand two hundred feet. Here the wonderful spectacle was presented of no less than seventeen thousand square miles of glaciers stretching over the face of the country. Excepting Greenland, according to this traveler, these glaciers are the most extensive in the world outside of the arctic and antarctic regions.