188 Declinations of Stars. 
laminated condition of the atmosphere may possibly be con- 
nected with the various contrary currents of air, which exist 
eontemporaneously in successivejaltitudes in the atunosphere. 
27. Vibration producing the primitive Colours.—Dr. Forster 
has also made a curious observation in looking at the stars 
through a telescope, by giving the telescope a gyratory motion, 
so as to cause the stars viewed at the time to describe a circle, 
giving a luminous ring in the field of view of the telescope, 
instead of a luminous point. It is remarkable that the ring 
of light thus produced is not uniform in colour, but is sepa- 
rated into the prismatic colours, each colour seeming to occu- 
py a certain portion of the circular ring of light. In rapid 
gyrations of the telescope dark lines are produced, which in- 
tervene between the several colours, giving the circle a bro- 
ken appearance. All of the fixed stars produced this diver- 
sity of colours, though tbe colours were very different in dif- 
ferent stars. Thus the blue was the moet conspicuous in 
Lyra: for though the successive portions of the ring were 
red, yellow, green and indigo; yet all these colours were 
weak compared with the blue. « Cygnz showed a prepon- 
derance of indigo, less yellow and blue. Beltageus pro- 
duced yellow, and intense red and green. Sirius showed 
much indigo, violet and portions of bright white light. Ca- 
pella much orange, red, green, and less of the more refran- 
gible colour. .4ldebaran principally red, with some green 
and very faint orange. .@rcturus produced a much less co- 
foured ring than the others; indeed its portions seemed to be 
orange and red running into each other. The planets Jupi- 
ter and Mars showed no colours at all; the rings produced 
by viewing them with a gyrating telescope, being only cir- 
cles of light of the ordinary and uniform colour of those 
planets respectively. When any identical star was observed, 
the same colours were produced in whatever direction the 
telescope was vibrated. 
Dr. Fe hints that the different distances fof the stars may 
be one cause of this curious disposition of the light; and 
that the fact that Arciurus resembles the planets, in not af- 
fording the colours in any great degree, may afford grounds 
for considering him as the nearest of the fixed stars. 
28. Declinations of stars proportioned to their Refrangi- 
bility —Dr. Forster has lately compared the deelinations of 
