An extract of a letter written Decemb. 28. 1666. by M. Auzout to the publisher, concerning a way of his, for taking the diameters of the planets, and for knowing the parallax of the moon; as also the reason, why in the solar eclipse above calculated, the diameter of the moon did increase about the end

I did apply my self the last summer to the taking of the diameters of the sun, moon, and the other planets, by a method, which one M. Picard and my self have, esteem'd by us the best of all those, that have been practis'd hitherto; since we can take the diameters to second minutes, being able to divide one foot into 24000. or 30000. parts, scarce failing as much as in one only part, so as we can in a manner be assur'd, not to deceive our selves in 3. or 4. seconds.