792 



SCIENCE. 



[X. S. Vol.. XVllI. Xo. 4(iS. 



The meeting, wliicli consisted of a morning 

 and afternoon session, offered many points 

 of interest to mathematical teachers. After 

 President Butler of Columbia University had 

 delivered the address of veelcome, papers on 

 various phases of mathematical teaching were 

 read by Mr. Harry English, of Washington, 

 D. C, Mr. Isaac JST. Failor, of Eichmond 

 Hill, Mr. Arthur Schultze, of New York City, 

 and Mr. J. L. Patterson, of Philadelphia. 



A mathematical exhibition of models, cal- 

 culating machines, teaching devices, rare 

 mathematical books, portraits of famous 

 mathematicians, etc., in the museum of 

 Teachers College, greatly added to the interest 

 of the occasion. 



The next meeting of the association will 

 be held at Columbia University, New York 

 City, about Easter time, and applications for 

 membership and other communications may 

 be addressed to Arthur Schultze, secretary, 

 No. 4 West 81st Street, New York City. 



In addition to the oificers, the following 

 were elected as council of the association: 

 Professor John S. French, Jacob Tome Insti- 

 tute, Port Deposit, Md.; A. M. Curtis, State 

 Normal School, Oneonta, N. Y. ; Harry Eng- 

 lish, Director of Mathematics, Washington 

 'high schools, Washington, D. C. ; John E. 

 Gardner, Irving School, New York City; W. 

 Z. Morrison, Shadyside Academy, Pittsburgh, 

 Pa.; Mary V. Shea, Commercial High School 

 for Girls, Philadelphia, Pa. 



SHORTER ARTICLES. 



THE PELE OBELISK. 



The most remarkable phase of the still con- 

 tinuing eruption of Monte Pele is the appear- 

 ance on the smnmit of the mountain of a 

 column of solid rock which is a conspicuous 

 feature even when seen from a distance of 

 fifty or more miles. The nature of this 

 ' obelisk,' the changes it has undergone, its 

 rate of ascent, etc., have been faithfully re- 

 ported by Professor A. Lecroix, Professor 

 Angelo Heilprin, Major W. M. Hodder, Dr. 

 E. O. Hovey and others,* but a more compre- 



* Science, November 13, 1903, Vol. XVII., pp. 

 633-634. American Journal of Science, October, 

 1903, Vol. XVI., pp. 269-281. 



hcnsive statement than I believe has yet ap- 

 peared in print, as to the place to be assigned 

 it in the sequence of events normal to volca- 

 noes, may be of interest to the general reader. 



The earlier of the recent eruptions of Monte 

 Pele and all of those of La Soufriere of St. 

 Vincent since early in May, 1902, as will be 

 remembered, were explosive. Neither volcano 

 has as yet discharged a stream of liquid lava. 

 Dui'ing the explosive eruptions referred to, 

 vast quantities of angular rock-fragments 

 were blown into the air, and fell on the ad- 

 jacent land and sea. The material thus 

 showered on Martinique and St. Vincent con- 

 sists for the most part of fresh lava, but con- 

 tains also large quantities of fragments of rock 

 of older date, which were torn from the inner 

 walls of the conduits through which the ex- 

 plosive discharges took place, and in addition 

 on the sides of each volcano there are many 

 ' bread-crust bombs ' as they are termed, or 

 masses of lava frequently two feet or more in 

 diameter, that were blown out of the craters 

 in a plastic condition and assumed rudely 

 spherical forms during their aerial flights. A 

 large portion of the fragmental material, but 

 more especially that composed of fresh lava, 

 is in the condition of fine dust-like particles. 



The nature and explanation of the explo- 

 sions referred to may be readily appreciated 

 by picturing in fancy, as may be done from 

 the evidence in hand, the sequence of events 

 during the eruptions. 



A volcano, it will be remembered, is a tube 

 or conduit leading from the earth's surface 

 sufiiciently deep into its interior to reach a 

 region of intense heat. In the case of the 

 Antillean volcanoes under consideration, the 

 conduits may be considered as rudely circular 

 in cross section and approximating five or six 

 hundred feet in diameter, and of great but 

 unknown depth. Through the conduits rock 

 material so hot that it was molten or rather 

 as is more probable, because of the great pres- 

 sure present, in a plastic and viscous condi- 

 tion, or a mac/ma, as it is convenient to term 

 it, was forced upward from a depth and 

 reached or made a near approach to the bot- 

 toms of the craters from which the products 

 of the explosions were blovm out. The magma 



