Recent Observations upon Solar Physics. 451 



examined consisted of such a mist giving a diffuse and incon- 

 spicuous spectrum, and of the intensely heated air entangled in 

 it giving; rise to a spectrum of bright lines, nine at least of which 

 partially escaped absorption and reached the earth. 



102. The particles of cloud in this case aet as the principal 

 carriers of heat, receiving it by radiation from the photosphere, 

 and communicating it by contact to the interspersed air; but 

 they are not without aid in discharging this office. In fact 

 wherever a bright spectral line is broader than the corresponding 

 absorption line of the ordinary solar spectrum, we may be sure 

 that the gas emitting it is exposed to direct radiations from the 

 photosphere of those wave-lengths which correspond to the pro- 

 jecting portions. 



103. Hitherto we have considered only the immense columnar 

 flame to the east of the sun, with a great spot close to its base* 

 which was probably caused by it (§ 72). But other spectroscopic 

 observations of much interest were made. Captain llaigf saw 

 a red line and a yellow line (probably C and D) in the spectra 

 of two broad protuberances on the western limb. Fortunately 

 the slit of his spectroscope was parallel to the sun's edge, the objects 

 under examination happened to be opposite the point where the 

 sun reappeared, and Captain Haig looked also at light coming 

 from a situation close to the disk. Just before the sun's emer- 

 gence he saw " a brilliant wide spectrum," in which the lines of 

 the prominences were lost and two other bright lines presented 

 themselves. This appears to be the only spectroscopic observa- 

 tion recorded o( light taken from a stratum low enough in the 

 sun's atmosphere to give a hope of seeing bright lines in the 

 corona. But from other observations it appears likely that a 

 rich harvest remains for other observers in this direction. MM, 

 Stephan and TisserandJ saw an arch of light bordering the 

 moon immediately after the beginning of totality, so bright that 

 the moment when the total eclipse began could not be decided. 

 Governor Hennessy§ saw the lower shell of clouds before the 

 close of the total phase as an arch running round one-fourth of 

 the circle : about twelve seconds after this he saw "a rough edge 

 of brilliant white light," probably glancing through valleys on 

 the moon, and in another second the sun bad burst forth. 



101. From these observations it. appears certain that the 

 brilliant wide spectrum which superseded the two narrow spectra 

 of protuberances in Captain ilaig's observations was the spec- 

 trum of the " shell of clouds " (§ 66) and the region between it 



* Proceedings of the Royal Society, vol. xvii. p. 79. See nlso p. 82. 

 t Ibid. p. ;i. 



:i; See 'The Engineer' o( November 13, 1868, p. :>7L 

 § Proceedings of the Royal Society, vol, xvii. p. S6. 



2 G 2 



