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Published online by Cambridge University Press: 17 January 2013
In the first part of this paper, I have endeavoured to prove, that the red prominences seen during total solar eclipses, exist in the sun; and I now propose to state some views which have occurred to me as to the nature of those remarkable objects, and their possible connexion with other solar phenomena. It is not, however, without great misgivings that I venture on this subject; for we know so little of the sun, that any hypothesis regarding the constitution of his atmosphere, can amount only to a conjecture, possessing more or less probability according to the variety of the appearances it serves to explain, and the exactness with which theory and observation correspond in each case: and I am well aware that views which may seem probable to myself may not appear equally so to others, whose greater experience in observing the sun constitutes them better judges of such questions.
page 461 note * Herschel's Outlines of Astronomy, par. 395.
page 461 note † M. Arago reasons in the same manner, in the Annuaire for 1852, p. 344.
page 462 note * Notice of R. Ast. Soc. for Jan. 1852, p. 67.
page 462 note † Ib., p. 69.
page 462 note ‡ Edinburgh New Philosophical Journal for Oct. 1851; or Astron. Nachrichten, No. 777.
page 462 note § Phil. Trans., vol. xxix.
page 462 note ∥ Notice of R. Ast. Soc, p. 59.
A red fringe also appeared towards the beginning and end of the total phase at the eclipse of 1842. Thus M. Schumacher, who witnessed the eclipse at Vienna, relates,—“Peu de temps avant la fin de l'éclipse totale, il s'éleva vers cette partie du disque lunaire d'ou devait jaillir le premiere rayon de lumière, une étroite couche d'un rouge rosé qui s'étendait, peut-etre, sur' un espace de 70 à 80 degrés le long du bord de la lune, et qui disparut, ainsi que l'anneau lumineux et les montagnes rouges, aussitôt que le premiere rayon du soleil jaillit.”—Annuaire for 1846, p. 433.
M. Struve remarks.—“Je crois avoir vu, un instant avant la disparition du dernier rayon solaire, une couche rouge au bord de la lune, à 45 degrés environ du point où le soleil disparaissait.”—Ibid, p. 437.
page 463 note * Philosophical Transactions, 1801.
page 463 note † Herschel's Outlines of Astronomy, par. 389.
page 463 note ‡ This is the mean of observations by Mr Williams and Mr Stannistreet. Notice of R. Ast. Soc. for January 1852, pp. 54, 55.
page 464 note * Dr Wilson of Glasgow, who, by observing a large solar spot, was led to the discovery that it was an aperture in the sun's luminous atmosphere, estimates the depth of its nucleus as “not less than a semidiameter of the earth below the level of the sun's spherical surface.” See his highly interesting paper, Philosophical Transactions, vol. lxiv., 1774.
page 464 note † Herschel's Outlines of Astronomy, 1851, par. 386.
page 464 note ‡ In certain circumstances steam has a red colour. May not the rose colour of the prominences indicate a property of the vapour composing them analogous to that possessed by steam, or, if they consist of aqueous vapour, identical with it? Professor Forbes, to whom we are indebted for our knowledge of the red colour of steam, regards it as the principal or only cause of the rosy tint observed in clouds.—See his interesting paper. Edinburgh Transactions, vol. xiv., p. 371.
page 465 note * Outlines of Astronomy, par. 395.
page 467 note * Sir William Herschel. Philosophical Transactions, 1801.
page 467 note † Sir William Herschel, who regards the faculæ as ridges, does not seem to hold that opinion very confidently. In his paper, already noticed, he only once states that they “have the appearance of elevations.”—(Phil. Trans. 1801, p. 84.) Mr Dawes, however, has recently observed a facula projecting beyond the sun's limb (R. Ast. Soc. Notice for April 1852). With reference to that observation, it may be permitted to remark,—that considering the rapid degradation in brightness of the sun's disc towards the edges,—it is evident that the dark glasses used in observing the sun may, to some extent, diminish its apparent diameter, the light from the extreme edge of the disc being possibly too feeble to be seen through the glass. A portion of the sun's limb brighter than the rest would be less encroached on from this cause, and would thus appear to project beyond the general outline. Irradiation would also conspire to increase this effect. The action of the dark glasses, in diminishing the sun's apparent diameter, may also be one of the causes of the anomalous variations in observations of the sun's diameter.
page 468 note * R. Ast. Soc. Notice, p. 53.
page 469 note * R. Ast. Soc. Notice, p. 47.
page 469 note † Ibid., p. 52.
page 469 note ‡ Ibid., p. 54.
page 469 note § Ibid., p. 57.
page 469 note ∥ Edinburgh New Philosophical Journal for October, p. 375.
page 469 note ¶ R. Ast. Soc. Notice, p. 67.
page 469 note ** Ibid., p. 60.
page 471 note * Annuaire for 1852, p. 342.
page 471 note † Arago, quoted by Humboldt, Cosmos, Murray's Edit., vol. iv., Notes, p. ciii.
page 471 note ‡ Annuaire, for 1846, p. 464.
page 471 note § Annuaire for 1852, p. 345.
page 472 note * Annuaire for 1846, p. 465.
page 472 note † Ibid, for 1842, p. 440, et seq.