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

MOTIONS OF THl1 PZIANETARY SYSTEIM. 215
firmed by calculaltng its orbit ol tilis supposition, and comlparing thle results with thc places it has actually occupied since
it fell withinl tlle sphlcroe of obslervation. Tlet results tihuis
ol)talied, however, were materially diflerent fiomt tlhos of lie
-\relier alld Adams. Instea( of a period of 9I1 years, tley
give onlly: a period of 1IAt- y)ears; ad instetad of a distalce of
3,600 illillions of mlies, the new period would requlil a (listatcol
of only ".,8h2 Jmilliols. The eccentricit)y of the orb1it, moreover,
accorldinil to Walker, is much less than h1ad )bect assignled to
it, tl obit t 01 citng ill ftct very nearly circular-, while,, by Le
Vcrri cr's estimate, it was considlcrably eliptical.'l'The longitrde, ill iact, proved to )e nearly thl same as that assigpetdl to
it. ]3ut this close agremcc ntl is to:be considered accidental;
for Le Ve rrir hllimself fihxed on the precise placC which lie
nllamed, as only the most probable. OOn account of uncertainty
il tle ldatta, lie stated:tllat there might be a Yvariation of 90
eit;ller way'Ttt h' e elements tlhus corr'ctCd account fully and
comple)tey rlo tlhe irregularities of Uranuls souigllt to bl csxp)laicned, within a sinlgle second, as determined b)y Profe ssor
Peir. ce. e
3O1TIONS OF TIl'E A'INE,,t'ARY SYSTE7M.
35i54t. We have c waitcd until tile learner may be supposed
to be fitlniliar with thl heavenly bodies idivridually, l)bftrei
invitingl ],is attention to a systcmatic view of tle plamnets in
their reXvolutions around the sUll, and their grand laws.
rThlro are two methods of arriving at a knowledge of thle
motions of thle heavc ly bodies. One is, to begin with the
aJp/at;rnt, and ftrom thlese to dedtlce the real motions; the
othlier is to begin with considering things as they really tare int
nature, land thln to inqutire whlt they appear as tlhey do. The
latter of tlhese methods is by far tlhe m1ore eligible.:It is much
casier tlhan tlhe other; and pr'oceedlin,, fi'om tlle less difficult to
that w\\llicll is mnorl so -f0lom mlotion1s wlich are vcr'y sim itle to
such aIs are complicated, it finally p)lts the learner in possessionl
of the whole mactthinery of the heatvcens. We shall iIn the first
place, therlefore, endeanvor to introduce tile student to an aco LXnomis's RIecett Prog. of Astron., pp. 60 -52.
-- Ailer. Journal of Science, Atu, &Sri.s, vol. v., p). 436.