28 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
of equivalents of carbon are inodorous. He ascribed the smell of 
prussic acid to arriére-gout rather than true odor. * 
Mr. Brxurncs showed that from the peculiarly exposed condition 
of the olfactory nerve-terminal, it was subject to irritations that 
must be distinguished from odors properly speaking. 
Mr. CLARKE then made a communication on 
“THE FLOOD ROCK EXPLOSION, 
in which he described the arrangements for observing earth tremor 
at stations near New York city, and particularly that at Ward’s 
Island, occupied by Mr. Mendenhall and himself. The tremor was 
felt at that station a full second before any disturbance was seen 
in the surface of the water above Flood Rock. 
Mr. C. F. Marvin, in a communication on the same subject, de- 
scribed the form of seismoscope used, in which a small agitation 
closed an electric circuit, and sounded an alarm. 
Mr. Paut followed with a communication on the same subject. 
Mr. CLARKE quoted some results of observations made at Gen, 
Abbot’s stations, giving a mean velocity for the tremor from Flood 
Rock to Pearsall’s of 2.6, and to Patchogue of 2% miles per second, 
and thus indicating a retarded rate of transmission. 
Mr. Rosrnson suggested that the blasts at the new water-works 
reservoir would afford a good opportunity for measuring the velocity 
of earth tremors. 
Mr. H. Farquyar spoke of the sounds coincident with the flight 
of meteors reported by some observers, as indicating the need of 
caution in accepting observations of sound in this connection. 
Mr. Rogrnson had distinctly heard two sounds after blasts at the 
water-works; one immediately following the tremor, through the 
earth, and a later one through the air. 
Mr. CHATARD had made a similar observation in connection with 
mining blasts. 
Mr. :Durron said that his impression, from eruptions of Hawaiian 
volcanoes, had been otherwise, and that the general testimony with 
regard to earthquakes is that the sound precedes the shock. 
