Jlogal Jnatitutt0tt of (Bxtai ?Sritain. 



WEEKLY EVENING MEETING, 

 Friday, January 23, 1903. 



Sir William Orookes, F.R.S., Honorary Secretary and 

 Vice-President, in the Chair. 



Tempest Anderson, M.D. B.Sc. F.G.S. M.B.L 



Hecent Volcanic Erujytions. 



There is a remarkable similarity between the islands of St. Vincent 

 and Martinique. Both are roughly oval in form, with the long axis 

 almost north and south. The north-west portion of each is occupied 

 by a volcano, the Soufriere and Mont Pelee, which have many points 

 in common. Both volcanoes show a single or practically single vent, 

 and a remarkable absence of parasitic cones and a scarcity of dykes. 

 In both a transverse valley exists to the south of the volcanoes, and 

 the main discharge of ejecta during the recent eruptions, which have 

 often been nearly synchronous, has been into this depression, and 

 especially into its westerly portion. In both islands, the recent erup- 

 tions have been characterised by paroxysmal discharges of incandes- 

 cent ashes, with comparatively few larger fragments and a complete 

 absence of lava. 



There are, however, a few points of difference. The eruptions of 

 St. Vincent have been altogether on a much larger scale than those 

 in Martinique. The area devastated was considerably larger, the 

 amount of ashes ejected probably ten times as great, and if the loss 

 of life was not so large, this is accounted for by the absence of a 

 populous city at the foot of the mountain. While both volcanoes 

 show practically a single vent, this is much more markedly the case 

 of St. Vincent, where, excepting the new crater, which is practically 

 part of the old or main one, there is not a single parasitic cone. We 

 saw no fumaroles, no hot springs, nor any trace of radial cracks or 

 fissures. 



On Mont Pelee, it is true, the main activity is confined to a re- 

 stricted area about the summit of the mountain, and the top of the 

 great fissure which extends or extended from this down in the direc- 

 tion of the Eiviere Blanche; and there are no parasitic cones com- 

 parable, for instance, to those which are so numerous on Etna ; but 

 there are many fumaroles which Professor Lacroix and his colleagues 

 speak of as emitting gases hot enough to melt lead though not copper 

 wire. A telegraph cable has been three times broken at about the 

 same place, and the broken ends on one occasion, at any rate, showed 

 marks of fusion. There are also several hot springs. Judging from 

 Vol. XVII. (No. 97.) u 



