Observation of the Late Transit of Mercury Over the Sun, Observed by Edward Pigott, Esq. at Louvain in the Netherlands; Communicated by Him in a Letter to Nevil Maskelyne, D. D. F. R. S. and Astronomer Royal

XXI. Observation of the late Transit of Mercury over the Sun, observed by Edward Pigott, Esq. at Louvain in the Netherlands; communicated by him in a Letter to Nevil Maskelyne, D. D. F. R. S. and Astronomer Royal. Read June 15, 1786. SIR, WE have been fortunate here in seeing Mercury's egress. I observed it thus: Apparent time, May 3. H. M. S. 20 45 25 Mercury's limb in contact with the sun's limb; uncertain. 20 45 37 ditto ditto; certain. 20 47 17 Mercury bisected by the sun's limb. 20 49 22 Mercury quite out; clouds for a short interval, which renders the observation rather doubtful. Though the air was not perfectly free from thin clouds, nevertheless the limbs were well defined. At 20 h. 45' 25", when I first judged Mercury's limb in contact with the sun's, his form, I think, became rather oval. These observations were made with Ramsden's two-feet achromatic, magnifying about 70 times. The above times disagreeing so considerably with the tables will, I imagine, not a little surprise M. de La Lande. I remain, Sir, with great regard, &c. EDW. PIGOTT. Eee 2