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rably. Sometimes they are nearer one another, fometimes farther afunder: Sometimes they are confiderably broader, efpecially that nearest the middle; Sometimes as confiderably narrower : fometimes they both advance towards one Pole, and then recede towards the other oppofite Pole. Of many of thefe Appearances I took Draughts, and defigned to have enquired whether they bad certain Periods; but want of Health and Leifure prevented me.

And not only the Belts, but the Spots alfo of Jupiter vary greatly; I do not mean the Spots occafioned by the Shade of the Satellites, but fuch as are on the very Disk; which are fometimes of one Form, fometimes of another; and oftentimes none to be feen at all, altho the fame Face of Jupiter should be towards us.

3. The last thing I shall mention is the Nebulofe, which are thofe glaring whitish

whitish Appearances, feen with our Telefcopes in Andromeda's Girdle, Hercules's Back, Antinous's Foot, Orion's Sword, in the Centaur, Sagittary, &c. which appear through the Telescope fomewhat after the manner as Cor Cancri doth to the naked Eye.

Thefe Nebulofe I have often viewed with Glaffes of very different Lengths, particularly that in pede Antinoi with Mr. Huygens's: but I confefs that I could never difcern what they are; neither indeed could I perceive any great Difference in their Appearances through a very good Glass of about 14 Foot, and others of 30 and 40 Foot, yea, Mr. Huygens's of 126.

But indeed the grand Obstacle to all my Views with Mr. Huygens's Glafs was the Vapours near the Horizon, which not only obfcured the Object, but caufed fo great a trembling and dancing thereof, as made it no less

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difficult

difficult to be diftinctly and accurately viewed, than a thing held in the hand is, when danced and fhaken backwards and forwards. By this means my Expectations from Mr. Huygens's Glafs were frequently frustrated, excepting in Nights that were more than ordinarily ferene and clear; which was commonly in fuch as were the most intenfely frofty and cold.

Finding it therefore unlikely that I fhould do much more with Mr. Huygens's Glafs than I had done, I reftared it to the Royal Society which lent it me, (and to whom Mr. Huygens bequeathed it by his laft Will) contenting myself with the Views it had given me, and that I had discovered it to be an excellent Glafs; which Dr. Hook, and fome others of our best fudges, took to be good for nothing.

And now having given this Account of my Obfervations, and alfo fhewed what hinder'd my compleating of them

(which may excite farther Enquiries, as well as ferve to vindicate myself) I fball recommend these things to fuch as have good Glaffes, particularly to the Diligence and Accuracy of my very ingenious Friend, the Reverend Mr. Pound, into whofe Hands the Royal Society have put that noble Bequest of Mr. Huygens, and who is fo well accommodated for raifing and using that Glafs, as to have feen (among other confiderable things) the five Satellites of Saturn; which I confess I could never reach, nor above three of them that I could be fure were Satellites: I fay that I could be fure were fuch, becaufe it is not very easy to diftinguish which are Satellites, and which are Small Telescopick Stars, which very frequently few themselves in a Glafs of fuch Goodness as that is. I remember that I once verily thought I had found out feven Satellites of Saturn with this very Glafs of Mr.Huy

gens,

gens, fo regularly were they placed in respect of Saturn. But when I came to examine them the following Nights, I found that there were really no more than two Satellites, the reft being small Fixt Stars. But Mr. Pound's Skill and Exactnefs in fuch Obfervations is, I know, fo great, (and I may add that of my fagacious Friend Dr. Halley too, who I hear bath feen the fame) that I do not fay this by way of Caution to them, although it may ferve as Such to many others.

And now for a Clofe, I shall take this Opportunity of publickly owning, with all Honour and Thankfulness, the generous Offer made me by fome of my Friends, eminent in their Stations, as well as Skill and Abilities in the Laws, who would have made me a Prefent of the May-pole in the Strand, (which was to be taken down) or any other Pole I thought convenient for the Management of Mr. Huygens's Glafs.

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