Page:Gods Glory in the Heavens.djvu/277

Rh within these few years that Ave could with certainty determine the distance of any of the stars, just because we had not till then the means of dealing with quantities so minute as a second; but so remarkable is our advance in this respect, that one star—viz., Capella—has a parallax (on which the distance depends) of only one-twenty-fifth of a second, or, on the circle in question, the one-twenty-fifth of the sixthousandth of an inch; and yet astronomers speak of its distance as certainly determined. And what renders the thing all the more wonderful is, that these small quantities must be extricated from errors far greater. No instrument, as well as no observer, is supposed to be faultless. The axis of the telescope may not be perfectly level—-it may not be precisely east and west; the telescope maybe set wrong on the axis; the observer may have some obliquity; and the atmosphere may turn the ray of light out of its straight course;—and each of these sources of error will occasion an amount of deviation far greater than the quantity to be ascertained. Yet the astronomer, by his formulae, hunts out truth so ingeniously amidst a maze of error, that he at last inevitably runs it dowi/. He has a ton of sand and gravel from which to extract a single shining grain of gold; and he sets to work so systematically, that, minute as it is, it cannot slip through his fingers. We have endeavoured to give a conception of a second on the rim of a brass circle; but it is also