y, 
i ON THE CIRCULATION OF UNDERGROUND WATERS. 395. 
Tredegar.—Water short for town supply, and iron and steel works, 
June till October. 
_ Aberayron.—Many springs failed. 
Llanidloes, Broomcliff—Many springs dry. 
Llandwrog, Glynllivon Park.—Springs dried up till late in autumn. 
Llanfairfechan.—Springs disappeared until December, but a 40-feet 
well held out. 
Report of the Committee, consisting of Mr. H. BAvERMAN, Mr. F. W. 
Rupier, and Dr. H. J. Jounston-Lavis, for the Investigation 
of the Volcanic Phenomena of Vesuvius. Drawn up by H. J. 
_ Jounston-Lavis, W.D., F.G.S. (Secretary). 
‘Tue Reporter has to state that his work has been greatly hindered by the 
unfortunate outbreak of cholera in Naples, and the stringent local quaran- 
tine measures as a result thereof ; these causes, combined with the super- 
stitions fears of the people at seeing any stranger, prevented work on 
‘Vesnyius being carried out during the autumn of 1884, Nevertheless, 
daily observations were made of the variations in the activity of the 
_yolcano, of which a careful record has been kept. 
_ Allimportaxt changes of the crater-plain, and in the cone of eruption, 
aye been photographed; copies of these photographs are exhibited at 
meeting. Descriptions of the small eruption of May 2 of 1883 have 
already been given in ‘ Nature,’ and the results of a microscopical exami- 
nation of the sides of the remarkable hollow dyke then formed will soon 
be published. The Naples section of the Italian Alpine Club have gene- 
rously undertaken to publish a journal of Vesuvius, which will contain 
reproductions of the photographs exhibited. 
_ The third sheet of the geological map of Vesuvius and Monte Somma 
(seale 1 : 10,000) has been completed by the Reporter, and is exhibited at 
the meeting. It required thirty-three field days, not including pre- 
liminary knowledge obtained by many excursions during the previous 
much Lhe difficulties in the execution of this map have not been so 
’ 
auch due to the complexity of geological structure as to the amount of 
detail necessary. This will be evident when the map is examined, for it 
will be seen that the gradual progress in the formation of a covering of 
soil to the lava-streams and the development of vegetation is indicated in 
no less than six different stages, thus rendering the map of agronomic 
valne. Much care and patience was necessary in tracing out the course 
of ancient laya-streams now covered by a thick layer of loam. As a large 
part of the area is covered by habitations and by small gardens enclosed 
by high walls, each of which was separately visited, much time was spent 
in the work. 
_ The relationship of the varying activity of a volcano in a Strombolian 
state to barometric pressure, the lunar tides, and rainfall, cannot but be 
regarded as important in solving some questions of vulcanology. Instru- 
mental means of measuring such present so many practical difficulties 
that a scale of activity has been drawn up, which requires only a few 
minutes to learn, can be practised by any one with good eyesight and mo- 
derate intelligence who is within visual range of the volcano, and, above 
all, requires no further outlay than pen, ink, and paper. The objections 
be mentioned after describing the process. 
