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. Signs, and which come from the Poles o f the Zodiack, are marked by Gold-Wires; as also the Equator, the Tropicks, and the Polar Circles.

Thcre is but one grcat Spring, the Primum Mobile, which puts all the res:in Motion. It is wound up by the Antnrcliquc Pole, and you may wind it•up to the Right or Lest Hand, without wronging any contrary Motion.And by the Arftique Pole, you may advance and retard this Movement, ityou {hould find any Inequality, without altering at all the great Spring.

IV. I applied my seif the last: Summer to the taking of the Diameters of ^ t0the Sun, JVIoon,- and the other Planers, by aMethod which one M. Picnrd and {‘ e ' r e , 'o/ tb!-‘vu~my seif have, esteemed by us the best: cf all those that luve been practis’d »<■//, >>•?

hitherto ; since we can take the Diameters to Second Minutes, being able to r ' f

"divide one Foot into 14000 or. 30000 Parts, searce failing as much as in m. Auzöut.one only part, so as we can in a nianner be asiured, not to deeeive our selves "■ 21. r>-

in 3 or 4 Seconds. I (hall not now teil you my Observations, but I mayvery well asture you, that the Diameter or the Sun has not been much lels' in his Apogce, than 31 min. 3/or40 sec. and certainly not lese than 31 min.

3y sec. and that at prclent in his Perigce it pasies not 31 min. 45- sec. andmay be lese by a second or two. That which is at the present troublesomcis, that the Vertical Diameter, which is the most easie to take, is diminislit,even at Noon, by 8 or 9 t'ee. because of the Refraclions, which are muchgreatcr in Winter than Summer at the tarne height ; and that the HorizontalDiameter is difficuk, because of the twist Motion of the Heavens.

As for the Moon, I never yet found her Diameter lese than 29 min. 44 or45 sec. and I have not seen it paß 33 min. or if it bath, it was only by afew leconds. But I have not yet taken her in all the kinds of Situations ofrhe Apogees and Perigccs which happen, with the Conjunctions and Quadra-turos. I do not mention all what can be deduced from thence ; I {hall onlyteil you, that I have found a way to know the Pamllnx cf the Moon, by themeans of her Diameter: vi\. It on a day, when the is to be in her Apogee orPerigce, and in the most Boreal Signs, you take her Diameter towards the Ho-rizon, and then towards the South, with her Altitudes above the Horizon.

For if the Observation of the Diameters be exact, as in these Situations theh loon changes not considerably her distance from the Earth in 6 or 7 hours,the Disterence of the Diameters will shew the Proportion there is of her Di-stance with the Semidiameter of the Earth. I do not enlarge, because thatas löon as one hath this Idea the rest is easie. The tarne would yet be pra-efised betrer in the places where the Moon pasies through the Zenith, thanhere ; for the greater the disterence is of the Heights, the greater is that ofthe Diameters. I do not Note, (for it easily appears) that if one werc underthe tarne Meridian, or the tarne Anmuth in two very distant Places, and tookat the tarne time the Diameter of the Moon, one would do the tarne thing jihougVr this Method gocs not to precilencls.

From what has been seid may be Collecled the Realön of the Observation,which W. Hcvcllus made in the last Eclipse of the Sun, (july 1. St. S. 1666.)rouching the Increafc of the Moon’s Diameter about the end. I am excecd-

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