( 711 ) 
VIII. An Account of a /mail Telercopical Comec 
feen at London on the loth of June 1717. 
by Edm. Halley, LL. D. R. Soc. Seer. 
« 
T hat the Number of Comets traverfing our So* 
lar Syftem is much greater than feme, on ac- 
count of the late rareneis of their Appearance, 
have fuppofed it, may be collected from feveral fmall 
ones which have within few Years been deferibed in the 
Memoirs of the fretfcb Royal Academy of Sciences.;; 
thofe diligent Obfervers alTuring us that they difeover’d 
one in Sept. 1698. another in Fehr. 1699. a third in 
^prtl 1702: and again a fourth in Novemh. 1707. none 
of which, as far as I can learn, were ever (een ’m,E»Sr 
Und\ all of them having been very obfeure and with- 
out Tails, by means whereof Comets ufually firft Ihew 
themfelves. And bcfides thefe, two other Comets with 
remarkably long Tails> the one in Movemb, 1689. the o- 
ther in Febr. 1701. pad by unobfervable in thefe our 
Northern Climats, they having great South Latitude, 
and their Motions dire(ded toward that Pole. Hence 
we may juftly conclude that the Returns of Comets arc 
much more frequent than is vulgarly reckoned, and 
chat it is only contingent that for thefe ; 5 Yeats no one 
of them has been feen and obferved by our Adronomers. 
But there may be dill a much greater Number of 
thefe Bodies, which by reafon of their Smallnefs and 
Didance are wholly invifible to the naked Eye ; fo that 
unlefs Chance do dire(d the Telcfcope of a proper Ob- 
ferver, almod to the very Points where they are (againft 
which there are immenfe Odds^ it will not be poffible 
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