Royai Society. 289 
Just published, A Treatise on Spinning Machinery, illustrated 
with plans of different machines made use of in that art, from the 
spindie and distaff of the ancients to the machines which have 
been invented or improved by the moderns. With some preli- 
minary observations, tending to show that the arts of spinning, 
Weaving and sewing, were invented by the ingenuity of females. 
And a postscript, including an interesting account of the mode 
of spinning yarn in Ireland. By Andrew Gray. 
_ Facts and Observations towards forming a new Theory of the 
Earth. By William Knight, LL.D. Belfast. 
Two Essays, one upon single Vision with two Eyes, the other 
upon Dew; a Letter to the Right Hon. Lloyd Lord Kenyon; and 
an account of a female of the white race of mankind, part of 
whose skin resembles that of a negro, with some observations 
on the causes of the differences in colour and form. between the 
white and negro races of men. By the late W. C. Wells, M.D., 
with a memoir of the author’s life written by himself. 
LI. Proceedings of Learned Societies. 
ROYAL SOCIETY. 
Feb, Lt A PAPER Was read, presenting arithmetical investiga- 
tions upon the Extraction of Roots, by Lewis Francis Bastard, 
Esgq., of Geneva; and one on the Variation of the Compass, by 
Captain John Ross, R. N. as 
_£eb. 18, A. paper by Captain Edward Sabine of the Royal 
Artillery, Ou the Irregularities of the Compass-needles of His 
Majesty’s ships Isabella and. Alexander, caused by the attraction 
of iron contained in the ships, she i ; 
Feb, 25. .A paper by Sir.H, Davy was read, relating to the 
F Ormation of Mists in particular situations. The fall of the 'Ther- 
mometer is greater after sun-set on land than on water. The 
author considers the known fact of the expansibility of water at 
_ temperatures below 40°, as the cause which preserves at a supe- 
rior temperature both the water and the superincumbent air. 
When the cold, and comparatively dry land-air annexes with the 
moister and warmer air resting on the water, the diminished tem- 
perature that results from this mixture, has a tendency to sepa- 
Fate a part of its moisture in the form of mist. 
A paper by Captain Edward Sabiue was also read, containing 
Observations on the Dip and Variation of the Magnetic Needle, 
and on the Intensity of the Magnetic F orce, made during the late 
voyage in search of a N.W, passage. The Dipping-needle was so 
adjusted, that, on reversing the poles, the dip remained unaltered ; 
and was kept in the direction of the magnetic meridian by means 
Vol. 53. No, 252. April 1819. T of 
