To perform which, the following Method is proposed to be observed; _viz._ That at certain times agreed on by two Observatours, making use of _Telescopes_, large, good and well fitted for this purpose, by a measuring rod, placed within the Eye glass at a convenient distance, that it may be distinctly seen, and serve for measuring small distances by minuts and seconds (which is easie enough in large _Telescopes_) that, I say, each of such observers, thus furnish't shall observe the visible way of the _Moon_ among the _Fixt Stars_, (by taking her exact distance from any _Fixt Starr_, that lyes in or very near her way, together with the exact time of her so appearing) and the then apparent Diameter of her Disk; continuing these Observations every time for two or three hours; that so, {152} if possible, two exact observations of her _Apparent_ place among the _Fixt Stars_ being made, at two places thus distant in _Latitude_, and as near as may be under the same _Meridian_, by these Observators concurring at the same time, her true and exact distance may be hence collected, not onely for that time, but at all other times, by any single Observator's viewing her with a _Telescope_, and measuring exactly her _Apparent_ Diameter. It were likewise desirable, that as often as there happens any considerable _Eclipse_ of the _Sun_, that this also might be observed by them, noting therein the exact measure of the greatest Obscuration compared with the then _Apparent_ Diameter of his Disk. For by this means, after the distance of the _Moon_ hath been exactly found, the distance of the _Sun_ will easily be deduced. As for the time, fittest for making Observations of the _Moon_, that will be, when she is about a Quarter or somewhat less illuminated, because then her light is not so bright, but that with a good _Telescope_ she may be observ'd to pass close by, and sometimes over several _Fixt Stars_; which is about four or five days before or after her Change: Or else at any other time, when the _Moon_ passes near or over some of the bigger sort of _Fixt Stars_, such as of the first or second _Magnitude_; which may be easily calculated and foreseen: Or best of all, when there is any _Totall Eclipse_ of the _Moon_; for then the smallest _Telescopical Stars_ may be seen close adjoyning to the very body of the _Moon_. Of all which particulars the two Correspondents are to agree, as soon as he, that is to joyn abroad, shall be found out; whereupon they are mutually to communicate to each other, what they shall have thus observed in each place. * * * * * _Of an Observation, not long since made in _England_, of _Saturn_._ [Illustration]