If even we assume, with Herschel, that the apparent
diameter of Arcturus is only a tenth part of a second, it still follows that
the true diameter of this star is eleven times greater than that of the Sun.*
[footnote] *'Philos. Trans.' for 1803, p. 225. Arago, in the 'Annuaire',
1842, p. 375. In order to obtain a clearer idea of the distances ascribed
in a rather earlier part of the text to the fixed stars, let us assume that
the Earth is a distance of one foot from the Sun; Uranus is then 19 feet,
and Vega Lyrae is 158 geographical miles from it.
The distance of the star 61 Cygni, made known by Bessel, has led
approximately to a knowledge of the quantity of matter contained in this
body as a double star. Notwithstanding that, since Bradley's observations,
the portion of the apparent orbit traversed by this star is not sufficiently
great to admit of our arriving with perfect exactness at the true orbit nd
the major axis of this star, it has been conjectured with much probability
by the great Konigsberg astronomer,* "that the mass of this double star can
not be very considerably larger or smaller than half of the mass of the
Sun."
[footnote] *Bessel, in Schum., 'Jahrb.', 1839, s. 53.
This result is from actual measurement.
Pages:
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309