Intelligence and Miscellaneous Articles. 393 
of their conformability, and at variance with the mapping of the 
district as executed by the Geological Survey. 
The importance of the Bagshot pebble-bed as a basement-line of 
the upper division of the Bagshot strata was shown, as was suggested 
by the author, so long ago as 1880. 
The synclinal arrangement of the London Clay was shown to have 
been produced before the deposition of the Bagshot series, though a 
certain amount of movement (with a resultant amount of 150 feet 
of tilting in 13 miles from south to north) has since taken place. 
2. “Notes on the Polyzoa and Foraminifera of the Cambridge 
Greensand.” By G. R. Vine, Esq. 
XLIV. Intelligence and Miscellaneous Articles. 
EXPERIMENTAL RESEARCHES UPON THE DETERMINATION OF 
THE DIELECTRIC CONSTANT OF SOME GASES. BY DR. IGNAZ 
KLEMENCIC, PRIVATDOCENT AND ASSISTANT IN THE UNI- 
VERSITY OF GRAZ. 
a author determined the dielectric constant of some gases and 
vapours by the following method :—A large condenser, con- 
sisting of 30 nickel-plated brass circular plates of 25°76 centim. 
diameter, was put upon a plate and covered by a glass globe 
fitting air-tight to the plate. The plates of the condenser were 
separated from each other by small ebonite plates 0°89 millim. 
thick ; but the rest of the space could be tilled with air or any other 
desired gas. The density of this dielectric medium could be varied 
within certain limits, and the pressure read off upon a manometer. 
The condenser was placed in communication with an air-pump and 
with two large glass globes by means of tubes provided with taps. 
The condenser and glass globes could be exhausted to a tolerably 
low pressure, and it was also possible by means of a branch tube 
to fill the condenser with any gas at a high pressure. When it 
was necessary to exhaust the condenser rapidly, it was simply 
placed in communication with the exhausted glass globes. 
This condenser was charged 6! times in every second, and dis- 
charged as frequently through a sensitive galvanometer by the use 
of a tuning-fork, from a powerful battery of 22 small Bunsen 
elements with solution of potassium bichromate. The deflection of 
the galvanometer-needle thus produced is, as is well known, a 
measure of the capacity of the coudenser. If the electromotive 
force of the charging-battery and the frequency with which it is 
charged and discharged remain the same, any change in the 
capacity of the condenser produces a corresponding change in the 
deflection of the galvanometer. 
Tf the dielectric constant of the medium varies with. the density, 
then every change in the pressure within the condenser must pro- 
duce a change in the position of the galvanometer-needle. The 
deflection produced in the present case by the discharge of the con- 
