448 Mr. G. J. Stoney on the Bearing of 



astray in attempting it, and no one that has ventured upon the 

 enterprise can deem himself secure. For, on the one hand, that 

 which at any stage of information appears the most obvious ac- 

 count of a phenomenon is often not the true one ; and the meagre 

 knowledge we have of solar phenomena seldom suggests much 

 beyond the obvious account of them ; and, on the other hand, 

 if we are led astray on any point, we have little to set us 

 right, as we cannot select our test ; and all we can do is to lay 

 down correct principles of interpretation, to bring to bear from 

 every quarter such shreds of knowledge or information as can be 

 laid under contribution, and to review all, from time to time, in 

 the most cautious and painstaking manner. 



We may therefore well hail with satisfaction the additional 

 news of the sun which the late eclipse has brought us. These 

 fresh items of intelligence are chiefly two : — that the light of the 

 corona, so far as it was examined (that is, in its upper regions), is 

 much of it polarized in planes passing through the centre of the 

 sun ; and that the spectrum of the prominences which were ex- 

 amined contained bright lines. It is with these particulars that 

 I wish at present to endeavour to deal. 



98. The protuberance upon which all the observers*, except 

 Captain Haig, appear to have bent their chief attention was an 

 unusually brilliant and lofty one on the eastern limb of the sun, 

 nearly opposite to a solar spotf. It emitted five bright lines, 

 and apparently four fainter ones not seen by most of the obser- 

 vers. Major Tennant satisfied himself that the hydrogen line C 

 was one of the bright lines, the sodium line D another, and 

 the magnesium line b a third J. He had not time to measure 

 more ; but his estimate of the positions of the two other lines 

 which he saw suggests their being the two other principal hy- 

 drogen lines, viz. F and the hydrogen line close to G. Lieutenant 

 HerscheFs measures identify one line with D, and place another 

 near F§. Mr. Lockyer, examining another prominence since 

 the eclipse, has satisfied himself that he saw as bright lines C, 

 F, and a line near D ||. M. Kayet, who records nine lines, sup- 

 posed the brightest lines to be B, D, E, F, and G, "judging 



* There is some uncertainty whether this was the prominence examined 

 by Major Tennant, since he speaks of the prominence he examined as being 

 on the preceding, i. e. the west, side of the sun. But his description of its 

 aspect does not seem to accord with the appearance of any other than the 

 great flame seen on the eastern limb, and he refers to its being conspicuous 

 immediately before the sun reappeared as evidence of its great height, 

 which also seems to imply that it was on the eastern side. 



t Proceedings of the Royal Society, vol. xvii. p. 79. 



X Monthly Notices of the Astronomical Societ}^, vol. xxviii. p. 245. 



§ See ' The Engineer ' of November 6, 1868, p. 346. 



|| Proceedings of the Royal Society, vol. xvii. p. 91. 



