Observations on the Transit of Venus, June the 6th, 1761, Made in Spital-Square; the Longitude of Which is 4^′ 11^{′ ′} West of the Royal Observatory at Greenwich, and the Latitude 51 degrees 31^′ 15^{′ ′} North; by John Canton, M. A. and F. R. S.

The diameter of the sun, in a horizontal direction, was measured just after the transit, and found to be $= 31' 30.8''$. The clock at Savile-House was several times compared with my clock in Surry-Street, from Friday evening, the 5th June, to Monday evening, the 8th June; so that I am as sure of the time at Savile-House, as if the observation had been made at my house in Surry-Street. Ja. Short. XXXIV. Observations on the Transit of Venus, June the 6th, 1761, made in Spital-Square; the Longitude of which is $4^\circ 11''$ West of the Royal Observatory at Greenwich, and the Latitude $51^\circ 31' 15''$ North; by John Canton, M. A. and F. R. S. Read Nov. 5, 1761. Having measured the diameter of Venus, on the sun, three times, with the object-glass micrometer, the mean was found to be 58 seconds; and but $\frac{6}{10}$ of a second, the difference of the extremes *. * With the same micrometer, the diameter of Venus was measured, off the sun, twelve times, March the 29th, 1758, about noon; and the mean was $1' 1'' 42''$; whence the diameter, at the time of the transit, ought, by computation, to have been $1' 9'' 19''$. The diameter of the sun, from four observations very nearly agreeing with each other, was $31' 33'' 24''$. The time, by the clock, of the internal contact, was $8 \text{ h } 17 \text{ m } 4 \text{s}$ Of the external contact - $8 \text{ h } 35 \text{ m } 27 \text{s}$ Of noon - $11 \text{ h } 58 \text{ m } 24\frac{1}{2} \text{s}$ Therefore the apparent time of the first contact, was $8 \text{ h } 18 \text{ m } 41 \text{s}$ Of the last contact - $8 \text{ h } 37 \text{ m } 4 \text{s}$ The two positions of Venus on the sun’s disc, [Vide Tab. VI.] in chords parallel to the equator, were determined by frequently measuring the parts of such chords on each side the centre of the planet, with the object-glass micrometer; which was done with difficulty, both on account of the clouds, and the telescope’s not having an equatorial motion. Let the arc $ATB$ represent a part of the sun’s limb; let $CFD$ be parallel to it, at the distance of a semidiameter of Venus; and let $OVX$ and $PVY$ be parallel to the equator. At $7 \text{ h } 14 \text{ m } 39 \text{s}$ A.M. apparent time, $OV$ was $14' 43''$, and $VX$ $5' 32''$. At $7 \text{ h } 57 \text{ m } 21 \text{s}$, $PV$ was $16' 36''$, and $VY$ $1' 56''$. These observations were all made with a reflecting telescope of 18 inches focal length, which magnified about 55 times. XXXV. Some