TRANSACTIONS OF THE SECTIONS, 5 
a continuation of the direction of the Alps. As before remarked, the Alpine chain 
is most perfect in the neighbourhood of the Mare Imbrium, viz. from a little 
north of Cassini to the west extremity of a bright portion of land extending from 
it to Plato—the chain being indented by the wedge-shaped valley ; the portion of 
bright land has but few mountains on it, and a few craters have been opened upon 
it. North of this portion of bright land, several detached mountains are scattered 
over the surface, interspersed with but few craters; and this territory may be 
regarded as the continuation of the Alpine Mountains, as far as the southern 
boundary of the Mare Frigoris, by two well-marked groups of mountains west of 
Plato, the chain-like character and general direction being confined to the higher 
peaks bordering the Mare Imbrium. “ Between this interesting group of rugged 
and mountainous land and the Alps, the Mare Frigoris intervenes at a lower level. 
The ‘fault’ before alluded to clearly indicates a sinking down of a portion of the 
surface of the Mare hereabouts, which is not only narrower than any other, but 
especially interesting from its being crossed by certain lucid streaks from the rayed 
crater Anaxagoras, which are more or less coincident with the promontories above 
mentioned.” The strait-like character of this portion of the Mare Frigoris, the 
existence of considerable mountain masses on ails side, the well-marked depression 
of the Mare below the group of mountains on the north, and the ascent on the south 
towards the rim of Plato strongly indicate the valley-like character of this part of 
the Mare Frigoris, and also that the group of mountains on the north may with 
great probability be regarded as a continuation of the great Alpine group on the 
south, a portion of the chain haying been depressed when the valley of the Mare 
was produced, 
On the relative Distances of the Planets from the Sun. By R. 8. Browne. 
The communication consisted of a new series of numbers which more closely 
approximate to the known distances of the planets from the sun than do those 
suggested by Bode, as shown in the following Table :— 
Bode’s Numbers. Numbers proposed. 
1 4 1 4 4 
2 443 df 2 44+ 3 i 
3 442:°3 10 3 7+ 4 11 
4 44.273 16 4 ll+ 7 18 
5 44293 28 5 184 11 29 
6 44245 52 6 29+ 18411 58 
ti 442°:3 100 fi 58+ 29418 105 
8 44253 196 8 105+ 58429 192 
9 44273 388 9 1924 105+58 355 
On the Star Chromatoscope. By A. Cuavvet, F.R.S, 
The scintillation and change of colours observed in looking at the stars are so 
rapid, that it is very difficult to judge of the separate lengths of their duration. If 
we could increase on the retina the length of the sensations they produce, we should 
have a better means of examining them. This can be done by taking advantage 
of the power by which the retina can retain the sensation of light during a fraction 
of time which has been found to be one-third of a second—a phenomenon which 
is exemplified by the curious experiment of a piece of incandescent charcoal re- 
yolving round a centre and forming a continual circle of light. It is obvious that 
if the incandescent charcoal during its revolution was evolving successively various 
rays, we could measure the length and duration of every ray by the angle each 
would subtend on the circle during its course. This is precisely what can be 
done with the light of the star. It can indeed be made to revolve like the incan- 
descent charcoal, and form a complete circle on the retina. When we look ata 
star with a telescope, we see it on a definite part of the field of the glass; but if 
