414 Geological Society :— 
A special feature in the design of the cam C relates to 
those cases in which the temperature of the controlling-bridge 
is from any cause persistently too high or (as in starting “all 
cold”) persistently too low. It is essential that in such 
circumstances the cam should neither become jambed at the 
end of its run, thus stopping the whole mechanism, nor lose 
touch with the comb K, so as to fail in operation when the 
adjustment of temperature has improved. The form given to 
the cam, and shown in fig. 2, secures this result. It should 
be mentioned that the comb K on either side of the toothing 
is cleared away to the level of the throats between the teeth. 
I wish to thank Mr. U. Young for the great help he gave 
me in the design of the instruments. Dr. C. V. Burton has 
also given me great assistance in writing this paper. 


LII. Notices respecting New Books. 
Die Dissozuerung und Umwandlung Chemischer Atome. Von Dr. 
JOHANNES STARK, Privatdozent an der Universitat Gottingen. 
Braunschweig: F. Vieweg und Sohn. 1903. Pp. vii+957. 
a author of this pamphlet has performed a very useful service 
in rendering accessible to a wide circle of readers the main out- 
lines and present position of a problem which must be regarded 
as one of the most fascinating ever presented to the man of 
science—a problem whose vast significance was first seriously 
thrust on the attention of the scientific public by the epoch-making 
discoveries connected with that most mysterious element—radium. 
After explaining the principle of electrolytic dissociation and its 
application to the theory of conduction in gases, electrolytes, and 
metals, the author gives an account of Rutherford and Soddy’s 
investigations on the cause and nature of radioactivity, and the 
evidence in favour of the view that the last link in the chain of 
transformations going on im radium consists of helium. A most 
useful appendix contains, in addition to various supplementary 
explanations, numerous references to the literature of the subject. 


Lill. Proceedings of Learned Societies. 
GEOLOGICAL SOCIETY. 
[Continued from p. 314. ] 
February 24th, 1904.—J. E. Marr, Sc.D., F.R.S., President, 
in the Chair. 
f ieee following communications were read :— 
‘ Kocene ran Later Formations surrounding the Dardanelles.’ 
By Lieut.-Col. Thomas English, late R.E., F.G.S. 
Our present knowledge of the older rocks, upon which the Tertiary 
beds surrounding the Dardanelles rest, only suffices to indicate the 
positions of the outcrops of a succession of schists, crystalline 
limestones, granites, and serpentines, which can be traced from the 
