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179)
Horizon.  And so the Refraction in the Atmosphere of the Moon may well be found, by making many accurate Observations of proper Eclipses of fixed Stars, whose Places be accurately known: As suppose in her Transit under the [[underlined]] Pleiades [[/underlined]] or [[underlined]] Hyades [[/underlined]]: And N.B. by OBSERVING, at the same Time, most exactly her apparent Diameter.  For the Difference between the apparent [[underlined]] Diameter [[/underlined]] of the Moon [[underlined]] found [[/underlined]] then by immediate Observations, and the Diameter of the Space hidden by the Moon in the Celest ^ [[insertion]] i [[/insertion]] al Sphere, and which would account best for the Beginnings and Ends of those Eclipses, supposing that the Rays of Light suffered no Refraction in the Moon's Atmosphere; That Difference, I say, will give four times the horizontal Refraction of Light in the Moon's Atmosphere: Which Refraction will by consequence be known.  See, in [[underlined]] Parker's Ephemeris [[/underlined]] for 1738; four Transits of the Moon under the [[underlined]] Hyades [[/underlined]], described for the Month of [[underlined]] December [[/underlined]] 1737, and for the Year 1738.
   5. The inlight ^ [[insertion]] e [[/insertion]] ned Part of the Moon being more than ninety Degrees, by a Zone of about 18 Minutes; we shall have a very long Time, during which we may take  promiscuously the Altitudes of both the Limbs of the Moon.  And by consequence derive from them ^ [[insertion]] her [[/insertion]] apparent Diameter.  For her Diameter perpendicular to the Horizon continues long to be terminated, at both its Ends, by the bright Part of her Limb.  This would last for about 36 Minutes of Time, if the Moon did not move towards the East:  And will last about one Hour and a Quarter, because of that Motion of the Moon.  And thus the taking of Altitudes of the Moon may be sufficient to measure her Apparent Diameter by; without the
 

Transcription Notes:
edited mainly to make tags more consistent -megshu