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These Spott, havethisPeculiar, which distinguisheth them'srora all others,that they are found precisely in that Place of Jupiter, where some Satellite isseen by the Sun ; that they go front the Oriental Limb to the Occidental ofthe Distjue of Jupiter, with a Motion always equal to that of the Satellite ; thatin refpect to us they preceed the Satellite, before the Opposition of Jupiter tothe Sun, and follow him after-the Opposition ; that the further Jupiter is di-stant front the Opposition, the greater is the apparent Distancc of the (anteSatellite-, that at divers Times of the Year, this Distance changeth in Propor-tion of the Annual Parallax of the Satellite, according as he is differentlvleen by the Sun, and by the Earth, and that at one and the fame tmte ofthe Year, when divers Satellites happen to bc between Jupiter and the Sun,the Spots correlpondeiu to them are distant front them in Proportion of theSemidiameters of the Citcles of the tarne Satellites.

8- -^ n ' 1666. Jan. 2.6. about Zi, 1 5^ in the Mornfng, I pereeived ( with ffj Dr. Hook.a 60 Foot dass; near the Middle of the Zone d, a very round Spot, like" - u -?- 2that represented at g, which was not to be percieved about half an Hour f ' s ' I39 ‘before ; and I observed it in about io', time to be gotten almost to d, keep-ing equal Distance front the Satellite h, which moved also Westwardly, andwas joined to the Disk at i, at Zk iy', so that it was fufficiently evidentthat thisblack Spot was nothingelie, fave theShadowof tivzSateflite h, Eclip-stng a part of the Face of Jupiter. The otjier three Satellites in the tinte ofthis Eclipfe were Weftwards of the Body of Jupiter.

LXXXIX. 1. Anni duo & amplius elapsi sunt ex quo Eruditiifimus Tfo £/«« ut'onschatdus Townleius Armiger, mihi Maximas Jovialium Siderum a Centro J 0 - »f Jupi«r’sSa-vis Digressiones, k seipso observatas, necnon & Motus cuiusque Medios, Mo- tellit f ; &tuumque illorum Radices, ab Observationibus ejus deductas, Townleio. fuoTS TS‘accommodatas, communicavit. Ab eodem deinceps Ephemerides tuas, Claris 4°;?- ».'<-4. ’sime C affine, Mcdiccorum Siderum An. 1668. impetravi • quibus quando cum f ’ ^° 3J ' "* 9 *'Motus tum Motuum Radices, necnon & summas Elongationes a Te consti-tutas, nonnihil a D. Tovenleif inventis dissidere comperui, & Ego, quod ipseimpensius hortatus est, nonnullas prima quoque Occasione Oblcrvanpnes in-stituere Operae fore pretium duxi. Micrometro itaque Sc Tubo 14. P e d.An.i6ji. Menso 2 l 4 ar. Stil. Jul. sequentia qua potui Cura Experimenta pri-ma feci, Observationibus, in majorem Certitudinem, identidem quaque Nocteiteratis. .

An. 167 z. Mar. 19^ -7K

2.7. 8.28. 8.

11 si Limb. Jovis remotior a 4 ttf. Satellite dist.

1601 *—.9'—q 4 /y * 9 > v t /Limb. remotior ab eodem Ato. Satellite

1591—9—zoEadem Distantia--15-98=9-—qq

Jovis Diameter pluribus observationibus reperta 12.8. Ergo Semidiame-ter ejus 64; qua divisis Distantiis observatis, apparentes sient Satellitis aLimbo Jovis Remotiori Distantiae in Semidiametris ejus,

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