LET. XVXII. OF THE SUN, MOOts, AND PLANETS. ZOZ

bears to the distance of Venus (V) from theearth, in fig. x. So that if one observer fliouldbe placed at a, another at b, and a third at d,the observer at a would see Venus on the fun at/; the observer at b would see her on the sun atg ; and the observer at d would see her on thesun at h ; all at the same instant of time.

Or if Venus continued at rest at v, whilst theobserver at a was carried from a to d, by theearth’s motion, Venus, in that time, would ap-pear to him to have moved from f to h, on thefun. But the line / g h, in fig. 2, is longerthan the line F G H in fig. 1 ; and thereforethe nearer the earth is to the fun, the greaterwill the space be through which Venus appears tomove upon the solar disc, by the observer’s realmotion along with the earth, in any given time :and the further the earth is from the fun, theless will the space be through which Venus ap-pears to move upon the solar disc, by the ob-server’s real motion, in the fame time.

And, consequently, as Venus is really movingin her orbit in the direction T V W, (fig. 1.) ortv w, (fig. 2.) whilst the observer is carried bythe earth’s motion on its axis from A to D,or from a to d, it is plain, that Ihe will ap-pear to move sooner over the sun, if the earth’sdistance be only b v s, (fig. 2.} than if it beB VS, (fig. x.) So that the whole durationof her transit over the fun must be shorter, if

the