
TOTAL SOLAR ECLIPSE OF 1851. 511 
was crystallised. Balls of plaster of Paris, zinc, brass, transparent and opal 
glass, were tried: the best results were obtained with the last; when scratched 
with a diamond, there appeared only a little pink prominence here and there; 
often appearing exactly like those pictured by the eclipse observers. 
This pink light was, however, always thrown off from some object out of 
focus, though the visibly bounding line of the sphere might be in focus; and 
again, the light belonged to the ball as a centre, and not to the sun, seeming, 
therefore, to be a different phenomenon to the eclipse prominences; though the 
parallel direction of the rays grazing the moon’s edge, and the converging of 
those touching the ball’s, should be taken into consideration. 
A more similar experiment in this way, is to eclipse the sun behind a distant 
object; and for this purpose I placed a black tin screen on the top of Nelson’s 
Monument, and observed it from below with the naked eye and a small telescope. 
When the sun was completely eclipsed by the disc, there was much light of a 
spectrum character, with a preponderance to orange and red, thrown off beyond 
the edge, and this light was most abundant on that part of the circumference of 
the tin disc, to which, at the time, the sun was closest: thus bearing some sort 
of relation to the observed fact of the lengthening of the red prominences on that 
side of the moon to which the sun was advancing. Anything transparent, as a 
bristle, on the edge of a disc, was particularly vivid, and some ropes in the neigh- 
bourhood were “glorified” over an extent of two degrees. This effect, too, was 
more marked the clearer and more transparent the atmosphere. With much haze 
in the air it vanished altogether; the disc and ropes then projecting themselves 
blackly on the bright sky behind. This would seem also to be in some measure 
in favour of the idea of a spurious origin at the moon’s edge for the eclipse pro- 
minences. The evidence, however, is so very uncertain, that few things would 
be more productive of advantage in the present state of the subject, than the 
repetition of all the experiments with a better instrument, either in the rarified 
atmosphere of the Peak of Teneriffe, as just mentioned, or that of some higher 
mountain: such observations, too, made at once, might tend to save and to 
utilise much valuable time on the occasion of the next total eclipse of the sun. 
VOL. XX. PART Il. OY 
