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

304- FIXD)'TARl'S.
double that of the carthf in its orbit........-amountilng to about one
thousland millions of Imiles per annum.
On account of the smallness of the supposed parallax th1us
found, it wouldl ot be unreasonable still to entertain a lingering sutspiciomn, that it is nothiing more t:han t]he unavoida}ble imlp)erf'ctilon of instrumental mcasurements, as proved to be the
case in previous attempts to find the same clement; )but the
ost satisfactolry evidence whliclh tile world can have that sucht
is not t!he fact il the piresent instance, blut thtatt the p1arallax is
truly foulnd, is thlat tile most celebrlated astronomers of the age,
~aftcr rigorous scrutiny, have acknowledged the reality alnd
soundness of the determination. Our confidence tlhat the plarallax of 61. (yglli \as truly determinedl by Bessel, is strengthetcd by tile fact that a separate determination recently made
by Peters at thie _Pulkova Observatory, gives almost p recisely
the same result, that of B3cssel being 0'".348, and thtat of PI.eters
0".3t49. XIn tihe ease of several star1s still more distanll, tahe paraltaxl has been found, \with more or less probability, but with
sufficient to command the gencral confidence of astronomerls.
T'hils, tile parallax of Arcturus, Alpha Iyro, and Polaris, were
also folund by Peters to be respectively 0".lt 7, 0".:123, 0".067,
tlhat of thle tPole-star beintg only onc-iftll as great as tthat of 6
Cygni; and, consequently, if light would require 9J- years to
come from that star, it would require more than 4ll yeart s to
come to us fiom the Pole-star. A star in the southern hlmisp)hcre (-. 6Oewktrit'z) indicates a. p)arallax of about:.", and lienco
appears at present the nearest of the fixed stars.
4316. NXATUREt 0oF TlrEl STARS.
l'Ite stars amre bodies g/reater tMawt outr' cartl/. If tils w\re not
the case they could not be visible at such an inimmnlt se distance.
1)Dr. Wollaston, a distinguisheld ]lEnglish p)hilosoplte, attempted
to estimate thle magnitudes of certain of the fixed stars fioln
the light wllich they afford. Bly means of an accurate p)lotolmcter (an instrumaenit for measluring the relative intensities of
light) lhe compared tlie lighlt of Sirius with that of the sutit.:11le next inquired lhow flar tile sun Imust I)e removed firom us
in order to appealr no brighlter than Sirius. lie founld the distance to be 14t1,400 times its resenit distance. But Sirius is