An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

* 262, COMN1T1S.
On comparing these elements, no doubt could be entertained
that they )elongted to one and the same body; andl sillc. thl
interval between the stuccessive returns was seen to be 75 or 7 6
years, 1Ialley ventured to predict that it would again ret.urn i~:t178. Accordingly, tlhe astrionomers wvllo lived at that periodt
lookedl for its rCtunl with. thle greatest inteest, It wa\s t'ountd
however, that onl its wany towar-d t!fie sun it would pass very
near to J lupliter and Saturn, alnd by thlir action o it, would
be retarded for a long time. Claiiralt, a distinguisthed Frenchl
matelmatician, und(ertook tlhe laboriolus task of estimatinog the
exact amount of thlis retardation, andl found it to be no less
than 018 days, namely, 100 days by thle action of Jupiter, anld
518 days by that of Saturn. TI.his would dlelay its appeai-ace
ntil carly inl the year 1759, and Clairant fixed its arrival at
t.he perihelion withinl a 11mon0th of April 13th. It came to the
perillelionll on thle 12tll of iMarch.
401. T1he returnll of HIalley's comet in 1835 was looked for
with no less interest thaln in 1759. Several of thle most accur'ate matlhematicians of thile age had calculated its elements
Mtwitt inconceivable labor. Their zeal w as rewarled )by tlhe
appearance of thle expected visitant at the time and p)lace
assiued; it traversed( the northern sky p rsenting the very
appe.arances, in most respects, that had been anticipated; and
came to its p)erihelion onl thle 1. 6th of November, within one
day of thle time p)rcedicted by Pontecoulant, a Frencth matlhematician, who lad, it ap)pearied, madc the most successful calculation..:' On its pl'vxious return, it was deemed an extraordinary achieviement to have brought the prediction;'litlin a
month of the actual time.
i[anlly circ'iumstances conspiredl to render this return of Ialhev's comet an astronomical event of transeendent interest. 01O
all the celestial bodies, its history was the most remarklalble it
affoirded most triuitmpllant evidence of the trutll of thile doctrinell
of universal gravitation, and consequently of the received laws
of astronomy; and it inspired now confidence inl tle power' of
o SeI Professor Loomis's Observtions on I allcy's Comet, Amer. Journ. ScinceC,
xx., 209. Pontccoulsant's li'ys. C6leste P&cis, p. 586.