26 



SCIENCE. 



[K S. Vol. XXIV. No. 601. 



the rock-mass which built up the great Pelean 

 monolith may probably now be considered re- 

 moved. A period of many months' quietude 

 into which the volcano has entered has also 

 permitted of a closer approach to its center 

 theater of activity than has hitherto been pos- 

 sible, and given access to parts the study of 

 which can now be made directly rather than 

 inferentially. The Pelee obelisk exists to-day 

 only in its basal vsrreck, the jagged crest which 

 still protrudes in a partially severed connec- 

 tion from the summit of the supporting dome, 

 and in a wilderness of debris, composed of 

 small and giant fragments, which covers much 

 of the surface of the dome and fills in a con- 

 siderable part of the circumvallating hollow 

 (rainure) that separates the dome from the 

 bounding wall of the ancient crater-basin. 

 On the twenty-seventh of February of this 

 year, following an unusually easy ascent of 

 the volcano, I succeeded in gaining the floor 

 of the old crater by climbing over the sharp 

 arete of the northeast wall, and was soon 

 among the boulder-masses of the destroyed 

 obelisk. Fragments from two to three feet 

 in diameter to others measuring ten, twenty 

 or thirty feet, were everywhere, and they all 

 showed practically the same construction. 

 The rock is a compact, light-gray, and vir- 

 tually holocrystalline hypersthene-andesite, 

 devoid of vesicles or of any vesicular or ob- 

 sidian-like structure, and having a fine-grained 

 base. So far as an absolute reference is made 

 possible, it seems to belong to Lacroix's type 

 IV. (quartzitic andesites) of the ejected ma- 

 terial from the volcano.* Of course, it can 

 be that in parts of the debris that are now 

 covered up and no longer accessible fragments 

 might occur that are more or less vesicular 

 or scoriaceous in character, but in the very 

 large number of blocks that were examined 

 by me and my associate none having this char- 

 acter was detected. 



Climbing over the boulders, somewhat in 

 the form of stepping-stones, we gained a con- 



^ Professor L. V. Pirsson, of the Sheffield Scien- 

 tific School, has kindly looked over some of the 

 material for me. A more detailed study of the 

 rock will be made at a future day. 



siderable height on the dome itself, passing a 

 number of fumarolic vents from which the 

 disengagement of vapor was still fairly active. 

 Clumps of diminutive fern are now beginning 

 to grow about these. The partially free flows 

 of lava which enter as ribbed-structures into 

 the mass of the dome appear likewise as 

 compact andesite. I may remark here that 

 the sound of the falling masses which has 

 been likened to that produced by the breaking 

 of glass and porcelain, and from which a 

 possible vesicular structure was inferred, is 

 that given out by the compact andesite. 



As regards the origin and method of forma- 

 tion of the extruded andesite monolith, while 

 recognizing that the criteria for distinguish- 

 ing between a newly-made rock and one of 

 ancient date are not necessarily apparent or 

 of a nature to yield positive evidence, I have 

 no reason to change the view that I have else- 

 where expressed^ that it represented an ancient 

 plug or core that had been lifted up in the 

 manner of the giant granite mass (and 

 domite?) of the Puy Chopine, of the Auvergne. 



For the benefit of vulcanologists and seis- 

 mologists who are preparing catalogues of 

 eruptions and general volcanic disturbances it 

 may be proper to add that, despite reports to 

 the contrary, Pelee had not been in activity in 

 the early part of this year, and it took no part, 

 so far as outward appearances were concerned, 

 in the events which were associated with the 

 earthquakes in St. Lucia and Martinique on 

 February 16. The dome in its upper parts is 

 still quietly disengaging vapor. 



Angelo HeilpriNj 



THE COMMISSION FOR BRAIN INVESTI- 

 GATION. 



On May 27 the third meeting of the Com- 

 mission for Brain Investigation was held at 

 Vienna. This commission is one of several 

 established by the International Association 

 of Academies and has for its purpose the 

 advancement of neurological research, espe- 

 cially by the establishment of central insti- 

 tutes in the various countries, as well as by 



^ In Science and in my ' Tower of Pel^e.' 



