Dr. Jaggar on Volcanoes.

The Geological Conference met last night in the Geological Museum, and Dr. T. A. Jaggar, who was in Martinique and St. Vincent after the recent eruption, read a paper on "The Preservation of Human Life in Volcanic Lands." He divided his subject into two considerations--how to preserve life when danger is imminent, and how to warn people of probable explosions. In most volcanic outbursts, persons are killed by a steam blast, falling hot material, a sea wave, or a wind high enough to overset masonry. Some theory of protection against these forces may be found by inquiring into the cases of persons who have been saved from these dangers. Dr. Jaggar explained at some length the celebrated cases of the prisoner of St. Pierre, Martinique, and the overseer and men of the sugar refinery at Orange Hill. The prisoner was in a heavily constructed masonry cell having two small openings for air, and this cell was protected by the brow of a spur of cliffs. The man was burned somewhat by hot dust but was otherwise unhurt. In the case of the men at Orange Hill, they were in a large cellar which was absolutely closed. The explosive blast which followed the ignition of gases by lightning killed every one where there was open circulation of air, while the men in the cellar escaped entirely unhurt. From these and similar cases, Dr. Jaggar concludes that closed tomb-like places built of masonry present the safest refuge.

How to warn people of impending explosions is a much more difficult question. Dr. Jaggar read several extracts from St. Pierre papers, showing that the French scientists again and again concluded that Mt. Pelee was no longer dangerous, only to be terribly deceived. The intervals and character of the eruptions of Mt. Pelee give a basis for a calculation that the French disregarded. The first explosion was on May 3, and explosions of increasing violence came on May 8, May 20, June 6, July 9, and August 30--that is, at intervals of five, twelve, seventeen, thirty-three and fifty- two days. Dr. Jaggar has had several men at work plotting curves to fill this series, and the general result points to about December 20 as the date of the next explosion, if this theory is correct. The action of Mt. Pelee bears a great analogy to the action of geysers in these particulars.

At the end of his talk, Dr. Jaggar answered several questions asked from the floor, and explained more particularly the Orange Hill case. Owing to lack of time, Mr. Bowman's paper on the recent Springfield Excursion was omitted. He will read it, however, at the next meeting of the conference, November 18.