Alexandre Guy Pingré

“ I Had the honour to send you my memoir on the Parallax of the Sun as deduced from the observations of Venus; give me leave to add to it some remarks which I have since made, and communicated to our academy. The learned Societies of Europe, amongst which yours holds a most distinguished rank, will be the judges of the success of our expeditions. A definitive decision will probably not be formed till after the observation of the transit of 1769 ”

“ These observations follow one another very well, and they have been made by a man whom I know to be very skilful; but how the exit of Venus could appear to him to have taken up but 12′34′′ I must leave to persons skilled in natural philosophy to account for. The observation of the first contact, or of the internal contact of the limbs, would give you more than 12′′ for the parallax; that of the last would reduce it to eight; by a medium, the parallax would exceed 10′′. ”

“ This observation being compared with that of Tobolsk, would give 11′′ for the horizontal parallax, which is a little too much. Mr. Maskeline observes, that tho' Venus's limb and the Sun's appeared as defined as could be desired, yet when the artificial internal contact of Venus's limb with the Sun's was made by means of the object-glass micrometer, Venus's limb dilated and contracted itself alternately, getting and losing a small space within the Sun's limb. ”