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                                              172)

so nearly for the Phenomena of Solar Eclipses, it is only because the Errors in the Projection are counterballanced by an equivalent Error arising from the Neglect of a due Allowance for the aforesaid Refraction of Light. And this Consideration has afforded me one Method for finding that Refraction on: Beside which I have some other Methods for the same Purpose. 

[[Left margin]] These errors more manifest in Occultations of  *'s by [[symbol of  Moon]] Requisites to remove them. [[/left margin]]

26. But as to the Occultation of fixed Stars by the Moon, the Error will remain intire: Neither can it be avoided by any Compensation; but only by an indifferent Knowledge of the Parallax or Distance of the Sun; and a true Knowledge of the Proportion of the real Diameters of the Earth and of the Moon; and of the Refraction in the Horizon of the Moon; and of the Distance of the Moon from the Observator. Now these particulars cannot be truly and nicely stated without my Theory: But with it they may. Which being done once for all, at least coarsly for the Parallax of the Sun, and nicely for the Diameters of the Earth and of the Moon and for the Refraction of the Moon's Atmosphere: The Result of it in short will amount to the following Rule. 

[[left margin]] Rule to correct them. [[/left margin]]

27. From the apparent Semidiameter of the Moon; as increased by about two or three Seconds because of the Refraction in her Atmosphere; substract twice that whole Refraction: And the Remainder will give the Semidiameter of the Circle or Space, in the Celestial Sphere, which is intercepted from our Sight by the Interposition of the Moon. And from hence, and what I have already said, depends the Correction of the Calculations of the Immersion and Emersion of fixed Stars eclipsed by the Moon. But these Stars, moving along the Disc of the Moon, will seem to stick much closer to it, than we find they would do in