Junk 27, 1902.] 



SCIENCE. 



1033 



be better to kill and immediately destroy the 

 diseased animals. 



From both the military and economic points 

 of view surra must be looked upon as a very 

 serious matter, and its introduction into the 

 United States would result in very heavy 

 losses. 



Barton W. Evermann spoke on ' The Ameri- 

 can Species of Shad/ stating that from time 

 to time reports had been received by the U. S. 

 Fish Commission of the capture of shad in 

 the Mississippi basin, but that these reports 

 had proved either to have no foundation or to 

 be based on some other fish. In 1897, however, 

 Mr. James Sowders, of Louisville, forwarded 

 four specimens of a true shad, saying that he 

 had taken a few each year for many years 

 past, but that only recently had he captured 

 them in any number. The specimens proved 

 to be a new species, which has been named 

 Alosa ohiensis; it is more slender than the 

 Atlantic shad, and has fewer gill rakers 

 while it is much more slender than the Ala- 

 bama shad and has more gill rakers than that 

 species. 



F. A. Lucas. 



THE ACADEMY OP SCIENCE OF ST. LOUIS. 



At the meeting of June 2 — sixteen persons 

 present — ^Professor A. S. Langsdorf described 

 the factory tests that are made on electrical 

 machinery, illustrating the subject by lantern 

 diagrams showing the circuits employed for 

 the various tests, and by pictures of the ma- 

 chines as set up for testing in the factory. 



A biographical sketch of the late Dr. A. 

 Litton, one of the first members of the 

 Academy, by Dr. G. C. Broadhead, was pre- 

 sented by Dr. Hambach. 



Mr. H. A. Wheeler spoke of the occurrence, 

 at Hematite, Mo., some forty miles below St. 

 Louis, of a number of granite boulders, some 

 of them showing the polishing action of ice; 

 and accounted for their occurrence at this 

 point, or some fifty miles beyond the southern 

 limit of the terminal moraine, by the theory 

 that they had been carried there on cakes of 

 ice during the Loess period. 



Mr. Wheeler and Professor Nipher discussed 

 a recent newspaper account of the alleged 



finding of a meteorite that was recently seen 

 to fall in St. Louis, and agreed that the su.p- 

 posed meteorite, which both of them had exam- 

 ined, was merely a pyrite concretion from the 

 coal measures, of the type called 'sulphur- 

 balls' or 'nigger-heads,' which had probably 

 been raked out from the grate-bars of the ad- 

 joining factory, and passed ofi on its discov- 

 erer as a meteorite. 



Four persons were elected to active mem- 

 bership. 



William Tbelease, 

 Recording Secretary. 



DISCUSSION AND CORRESPONDENCE. 



THE EXPLOSIVE FORCE OF VOLCANOES. 



To THE Editoe op Science: Mr. A. E. Ver- 

 rill's hypothesis as to the explosive forces of 

 volcanoes, published in your columns. May 23, 

 1902, was most interesting. 



His theory as to the disassociation of the 

 hydrogen and oxygen of the water penetrating 

 by submarine channels to the base of the vol- 

 canoes accounts for many of the phenomena. 

 The separation is not immediate, but the water 

 is probably first converted into steam; this is 

 then superheated and the oxgyen is burned out 

 and the hydrogen liberated expands with ter- 

 rific force and its further heating gives it in- 

 creased power. This would account for the 

 groanings and rumblings in the mountain 

 itself before the outbreak. When the mass of 

 overlying matter is no longer heavy enough to 

 resist the immense internal pressure, it gives 

 way and a violent explosion or rather cyclonic 

 expansion of the imprisoned gases results. 

 This expansion is upwards, downwards and 

 outwards, following the lines of least resist- 

 ance. The surrounding atmosphere is at first 

 pushed back with a rush, but simultaneously 

 there is an effort towards readjustment. The 

 superheated hydrogen at once seeks to combine 

 with the cooler oxygen, and in the process of 

 readjiistment frequent discharges and flashes 

 of flame are seen which explode the mixture 

 of hydrogen and atmospheric air in combina- 

 tion. The process is now reversed and, in- 

 stead of expansion, we have immediate con- 

 traction and condensation. Water is at once 



