would have endeavoured to have kept the room (in which the clock stood) in the winter, and at all times, in the same degree of heat it had at the time I made the observations in the summer. I would also have daily observed and noted the moon’s place, at the time of the observations. Tho’ this is but a slight observation of mine; yet I make no doubt, but that in case, by the different distances of the earth from the sun, and the different distances and situations of the moon with respect to the earth, and the respective effects produced by these causes, any inequality arises in the velocity of the diurnal motion of the earth on its axis, you (who have made the most sublime observations on the aberration of the fixed stars, and more than any mortal ever did before) must have discovered, and are well acquainted, with the same. As my above-mentioned observations on the comet appeared too incorrect to undertake a calculation for the ascertaining of its path from the theory, I contented myself with effecting it by a construction. By this means I found, on a figure, whose globular or spherical diameter was 13½ Rhineland inches, as follows: That the comet was in its perihelion the 21st of October, at two of the clock in the afternoon: the place of the perihelion 3 degrees in Leo. The comet’s distance in the perihelion from the sun was about 34 parts, whereof 100 make the mean distance between the sun and the earth. The inclination of the comet’s orbit with the ecliptic 13 degrees; and the southern latitude of the perihelion also 13 decrees: the ascending or north node ☊ 4⅓ degrees in Scorpio; and the comet’s motion direct, or according to the order of the signs of the zodiac. On this supposition I have, for some of the times of observations, estimated the apparent places of the comet, and found them as follows: _Long._ _Latit._ Sept. 18, at 3¾ ante merid. In ♋ 18¹⁄₁₂ and 9 deg. North. 19 -- 4 -- -- -- ♋ 22 ---- 8⅖ 22 -- 2¾ -- -- -- ♌ 3⅝ ---- 6¼ 23 -- 4 -- -- -- ♌ 7⅗ ---- 5½ 25 -- 4¼ -- -- -- ♌ 14⅔ ---- 4 28 -- 4 -- -- -- ♌ 24⅓ ---- 1¾ Oct. 4 -- 4½ -- -- -- ♍ 9⅓ ---- 2 ---- South. 9 -- 4¾ -- -- -- ♍ 19⅔ ---- 3⅖ 11 -- 5 -- -- -- ♍ 23⅛ ---- 3⅘