of the Planet, both for an hour before, and an hour after, it arrive at the Meridian; and by a line, or stroke, amongst the small fixed Stars, they shall denote out the way that each of them observ’d the Center of the Planet to be mov’d in for those two hours:  These Observations each of them shall repeat for many dayes together, that both it may happen, that both of them may sometimes make their Observations together, and that from divers Experiments we may be the better assured of what certainty and exactness such kind of Observations are like to prove.  And because many of the Stars which may happen to come within the compass of such an Iconism, or Map, may be such as are only visible through a good Telescope, whose Positions perhaps have not been noted, nor their longitudes, or latitudes, any where remarked; therefore each Observator should indeavour to insert some fixt Star, whose longitude, and latitude, is known; or with his Telescope he shall find the Position of some notable telescopical Star, inserted in his Map, to some known fixt Star, whose place in the Zodiack is well defin’d.

Having by this means found the true distance of the Moon, and having observed well the apparent Diameter of it at that time with a good Telescope, it is easie enough, by one single Observation of the apparent Diameter of the Moon with a good Glass, to determine her distances in any other part of her Orbit, or Dragon, and consequently, some few Observations will tell us, whether she be mov’d in an Ellipsis, (which, by the way, may also be found, even now, though I think we are yet ignorant of her true distance) and next (which without such Observations, I think, we shall not be sure of) we may know exactly the bigness of that Ellipsis, or Circle, and her true velocity in each part, and thereby be much the better inabled to find out the true cause of all her Motions.  And though, even now also, we may, by such Observations in one station, as here at London, observe the apparent Diameter and motion of the Moon in her Dragon, and consequently be inabled to make a better ghess at the Species or kind of Curve, in which she is mov’d, that is, whether it be sphaerical, or elliptical, or neither, and with what proportional velocities she is carried in that Curve; yet till her true Parallax be known, we cannot determine either.

Next, for the true distance of the Sun, the best way will be, by accurate Observations, made in both these forementioned stations, of some convenient Eclipse of the Sun, many of which may so happen, as to be seen by both; for the Penumbra of the Moon may, if she be sixty Semidiameters distant from the Earth, and the Sun above seven thousand, extend to about seventy degrees on the Earth, and consequently be seen by Observators as far distant as London, and St. Helena, which are not full sixty nine degrees distant.