Concise Rules for Computing the Effects of Refraction and Parallax in Varying the Apparent Distance of the Moon from the Sun or a Star; Also an Easy Rule of Approximation for Computing the Distance of the Moon from a Star, the Longitudes and Latitudes of Both Being Given, with Demonstrations of the Same: By the Rev. Nevil Maskelyne, A. M. Fellow of Trinity College, in the University of Cambridge, and F. R. S.