454 C. Davidson—Growth of Lake Geneva. 
V.— Nore on tHE GrowtH or Lake GENEVA. 
By Cuarues Davison, M.A., 
Mathematical Master at King Edward’s High School, Birmingham. 
HOUGH the observations described in this note are not conclu- 
sive, they seem to me to show that the lake of Geneva is 
probably growing at the present time, and that a similar growth, if 
taking place beneath an ice-covering * on nearly level ground, would 
in time produce a true rock-basin. Unfortunately, the instruments 
used were very delicate levels, and experiments with such instru- 
ments prove that they are not to be trusted entirely for measure- 
ments of very small angles continued over a long interval of time.’ 
The observations referred to were made for several years by M. 
Ph. Plantamour at Sécheron, near Geneva. I have given some 
account of them in a former paper,® and will now only repeat those 
particulars which bear immediately on the present subject. 
Sécheron lies on the west shore of the lake, about a mile and 
a quarter north of the observatory of Geneva. ‘The shore-line 
here runs about 30° EH. of N. and 30° W. of S. and the slope of 
the ground must be roughly in a direction at right angles to this, 
i.e. about 30° §. of E. One of the levels is placed east and west, the 
other north and south. They show that, from day to day, the in- 
clination of the ground which forms the floor of M. Plantamour’s 
cellar is incessantly changing. The most noticeable movements are 
periodic, and are clearly caused by the annual and diurnal changes 
of external temperature. But we can eliminate these very nearly 
by calculating the average inclination throughout the year towards 
the east and north. This is done in the following table for the third 
to the eighth years, reckoning the average inclination during the 
third year as zero :— 
Kast. North. 
érd year (Oct. 1, 1880—Sept. 30, 1881). 200 0” 0” 
Nh Cape Gare aepyh CNL intsfimn OBITS Na ehh Ue ORB 1-11 
UL Re OUN Gen OO =n ae 1883). 500 5:07 2°92 
GN oo (CO ap 1883— _,, 1884). mae 11°66 3°82 
ED Rept (Guest, MeLSS4—— ae 1885). goo «AUS fe 4 5°60 
Sto ee she WS Soe tak 1886). coo GB) 7°60 
The inclinations during the first year are omitted because the 
N.S. level was not placed in position until nearly three months had 
elapsed; and those of the second year, on account of an unusually 
great movement in a direction somewhat south of east, which, of 
course, affected the readings of both levels. After the eighth year 
the N.S. level was removed and placed in an H.W. direction nearer 
* See Prof. Judd’s paper ‘‘ On the Origin of Lake Balaton, in Hungary,’’ Grou. 
Mae. Vol. III. 1876, p. 12. 
2 Tf similar observations were made for a few years in different parts of Switzer- 
land with a suitable instrument, such as the horizontal pendulum of Dr. E. von 
Rebeur Paschwitz, or the bifilar pendulum of Mr. Horace Darwin, the labour and 
money spent would meet with a rich reward. In this country observations of great 
re might be made near the north-east end of Loch Ness, say at Aldourie or 
ores. 
5 Phil. Mag. Vol. xxvii. 1889, pp. 189-199. 
