122 



Lieut. J. HerscheFs Account of the 



[Nov. 19, 



At 8 Tl 40 m . But ten minutes later the darkness was decided. 

 At 8 h 45 m . Thick clouds well broken up, stilt gathered most closely 

 in the region of the sun. Light becoming lurid, and increase of 

 darkness very apparent. 

 At 8 h 52 m . Cusps perfect (magnifying-power 27). 

 "Closely before totality a bright line of light appeared to shoot out 

 at a tangent to the moon's limb at its centre, as if running across the 

 bright crescent of the sun (though of course not visible against the superior 

 light) and extended beyond each cusp to a distance nearly, if not quite, 15'. 

 [Note by Lieut. H. The sketch in the margin 



represents Lieut. Campbell's meaning, as ^=^=^^^^^^^^m 

 ascertained orally.] The corona became vi- 

 sible immediately after, between the dark limb of the moon and the bright 

 line. The corona did not appear so bright as the line, the brilliance and 

 whiteness of the light of which was most striking. This was seen through 

 a highly smoked glass. At this period, probably not more than 3 to 5 

 seconds before totality ensued, a thick cloud shut out everything, and 

 the rest of the phenomenon was only seen fitfully through openings in the 

 clouds, for an aggregate period which I estimate at somewhat less than 

 half that of totality. 



"This alternate appearance and disappearance troubled me greatly, and 

 gave rise to nervousness and excitement ; for owing to the imperfect mount- 

 ing of my telescope I was apt to lose my place whenever the light was cut 

 off by clouds, and to waste the precious moments of clearness in finding it 

 again. 



"On the first opportunity after the commencement of the eclipse I turned 

 on the double-image prism with the eyepiece of 27 magnifying-power, 

 as recommended in the Instructions, which gave a field of about 45' dia- 

 meter. A most decided difference of colour was at once apparent between 

 the two images of the corona ; but I could not make certain of any such 

 difference in the case of a remarkable horn- like protuberance, of a bright- 

 red colour, situated about 210 degrees from the vertex, reckoned (as I have 

 done in all cases) with reference to the actual, not the inverted image, and 

 with direct motion. I then removed the double-image prism and applied 

 the Savart's polariscope, which gave bands at right angles to a tangent to 

 the limb, distinct but not bright, and with little, if any, appearance of 

 colour. On turning the polariscope in its cell the bands, instead of appear- 

 ing to revolve on their own centre, passing through various phases of 

 brightness, arrangement, &c, travelled bodily along the limb, always at 

 right angles thereto, and without much change in intensity, or any at all in 

 arrangement. 



"The point at which they seemed strongest was about 140° from the 

 vertex, and 1 recorded them as black centred. 



" Believing that with a higher power and a smaller field I should find it 

 easier to fix my attention on one point of the corona and observe the phases 



