4^8 Proceedings of the Cambridge Philosophical Society. 
dalene College, in whieh motion was produced by the successive 
explosions of a body of gas ; and a paper, containing an account 
of the principle and construction of the engine, was read by 
its inventor. Mr C. stated, that there are two ways in which 
explosions may be applied to move machinery, either by using 
the expansive force of the explosion, or by taking advantage of 
the vacuum which it produces. The contrivance described on 
this occasion belongs to the latter class. A piston moves in a 
cylinder ; and as it retreats, the space which it leaves is occupied 
by a mixture of hydrogen gas and atmospheric air. When this 
mixture has very nearly filled the whole cylinder, the motion of 
the piston opens a small aperture, through which the flame of a 
lamp is drawn in, so as to produce an explosion, followed by an 
instantaneous condensation. The expansion of the gas during the 
explosion, (by which it is dilated to about three times its origi- 
nal bulk,) is provided for by two other cylinders communicating 
with the one already mentioned ; aud the vacuum produced 
under the piston continues the motion by means of atmospheric 
pressure. The author also examined the advantages of this 
contrivance, the best proportion of the gases, the force of the ex- 
plosion, and the extent of the expansion, together with some cu-. 
rious irregularities in the working of the machine when the velo- 
city is increased beyond certain limits, 
Dec. 11. A paper by Dr Haviland, containing the details re- 
specting the case of a young man who died on the 17th day of 
a fever of the common continued kind, which was unaccompa- 
nied by any unusual symptoms or remarkable affection of the 
abdominal viscera. An examination was made about twelve hours 
after death, when the upper and back part of the stomach was 
found corroded in two places, where the coats of the organ were 
entirely destroyed. The larger opening communicated with a 
corresponding hole in the diaphragm, through which the great- 
er part of the contents of the stomach had escaped into the cavi- 
ty of the thorax. Scarcely any thing had been swallowed by 
the patient for more than twelve hours preceding his death. 
A translation was read by Professor Lee, from an ancient 
Arabian author on geometry, of a demonstration of the funda- 
mental propositions on the doctrine of parallel lines. 
