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Appendix II.

of measuring the Difference between theapparent Diameter of the Sun at the Timewhen the Earth is nearest to and farthestfrom the Sun, with a Micrometer placedin the Telescope invented for that Pur-pose. Though the Charge, or magnifyingPower of the Telescope is so great, that theWhole Sun’s Diameter does not appeartherein at one View.—“ This, fays Mr-“ Savory, I doubt not, will at first Sight" seem impossible, since only a Part of the" Diameter appears, and' no visible Mark" or Point therein from which such Mea-" sure can be taken. And, indeed, it is“ so by Observation with our common Te-" lescopes, whether refracting or reflecting" ones. I have therefore contrived some" Dioptric Telescopes, and a reflecting one" either of which, by representing the Ob-" ject double, will, if well made, answer‘‘ the Design.”

After this he proceeds to shew at large,by cutting of a large Object-Lens into fourParts or Segments, and combining the twoouter ones together, or the two Middleones inverted, how he could form thisdouble Image of the Sun; but as thoseImages were not well defined and free fromColours, he proceeded to a third Methodef forming thole Images by Means of two

Object-