226 The Limar Eclipse of September 13. 



Still, as lunar eclipses are tolerably frequent, and, unlike 

 solar eclipses, are visible over half the hemisphere of our globe, 

 I cannot but conclude that such a total absence of colour 

 during eclipses of considerable extent are very rare. 



ON COLOURS SEEN DURING THE LUNAR ECLIPSE, 

 SEPT. 13, WITH REMARKS ON THE PRECEDING 



COMMUNICATION. 



BY HENRY J. SLACK, F.G.S., SEC. E.M.S. 



It was with much surprise I heard from Mr. Browning that his 

 views of the late lunar eclipse through Mr. Barnes's 10^--inch 

 telescope, so far from disclosing any decided chromatic effects., 

 led him to express a positive opinion as to their absence. I 

 watched the same eclipse at intervals through a telescope 

 similar to that of Mr. Barnes's, with a silvered mirror, but of 

 smaller size (6^-inch), and furnished like his with a right-angled 

 prism, to direct the cone of rays to the eye-piece. On referring 

 to my notes I find the following : — " As shadow came over 

 Aristarchus, that crater remained visible, and rather bright, 

 until shadow advanced to near Eratosthenes, when it required 

 sharp looking for to see it. The shadow was inky purple, and 

 the sky colour in the neighbourhood dusky red. As shadow 

 passed over different portions of the Moon, the darkness varied 

 considerably, being much less over highly-reflecting portions 

 than over the seas, which became very dark. After twelve the 

 eclipsed limb grew noticeably redder, and objects likewise be- 

 came gradually more visible. The red, coppery tint chiefly affected 

 the lower part of the obscured limb, but was visible further in, 

 gradually blending with the inky tints presented by the umbra 

 at its advancing edge. By twenty minutes past twelve the in- 

 creased visibility of obscured parts very striking. 12.20, 

 eclipse at its height, and visibility of objects in obscured parts 

 much greater than at an earlier period. As the Moon passed out 

 of shadow, a brightening took place in opposite directions at the 

 two edges of the limb, and bluish tints of brighter hue been* 

 conspicuous, contrasting with the reds/' I added to this, 

 "Red colour less conspicuous in telescope than in opera-gla 

 with two-inch lenses/'' My wife's report of what she saw 

 g< aerally agreed with mine, but she noticed a greenish tint at 

 the beginning of the eclipse in the penumbra, and did 

 not si c the blue as much as I did towards its termination. 1 

 think her eye is more sensitive than mine to the peculiar 



