388 Proceedings of the Cambridge Philosophical Society . 
and which, when it raises its head and upper extremities, con- 
taining protuberant mammae, above the water, may probably 
have given rise to the fable of the Indian mermaid. He likewise 
read remarks by Dr Traill of Liverpool, on American Animals 
of the genus Felis . 
Art. XXI. — Proceedings of the Cambridge Philosophical So- 
ciety for 1822. (Continued from VoL VI. p. 378.) 
Feb. 25. — “ Some observations on the Weather , accompanied 
by an extraordinary depression of the Barometer , during the 
month of December 1821,” by the Rev. J. Hailstone, M. A. late 
Woodwardian Professor. 
Mr Henslow concluded his paper on the Geology of An- 
glesey 
March 11. — The meeting was adjourned in consequence of 
the death of the Vice-President, the Rev. Dr Clarke, Profes- 
sor of Mineralogy. 
March 25. — “ Description (fa new Self regulating Lamp f 
by the Rev. W. Mandell, B. D., Fellow of Queen’s College. 
The peculiar advantages of this lamp are, l*tf, The surface 
of the oil in the burner is constantly at the same distance from 
the flame ; 2d, That it consumes all the oil . 
H. B. Lesson, Esq. read a description of a safety apparatus 
attached to the Hydrostatic Blowpipe of Tofts, by which it may 
be converted into an oxy-hydrogen blowpipe, without danger to 
the operator. 
A paper was communicated to the Society by G. B. Airy, 
Esq. of Trinity College, the object of which was, to inves- 
tigate, on the Newtonian Theory of Refraction, the altera- 
tion which would take place in the focal length of an object- 
glass, from an alteration in the velocity of light, whether ari- 
sing from the motion of the earth, or from a motion in the stars 
or bodies observed. It was then proposed, after verifying the 
theory by observations of the same star at opposite seasons of 
the year, to determine the proper motions of the stars in the di- 
rection of lines drawn to the earth, by observing the focal length 
