Sidereal Astronomy . 
1876.] 
Great Bear, are white. This whiteness is so bright that for 
certain stars they appear even slightly tinted with blue, 
To compare the colour of the stars with leach other, and 
to deduce results applicable to the colouration of the double 
stars, I have invented an apparatus which forms optical 
couples with all the simple stars of the firmament, by 
bringing them as near together as may be desired, and 
which measures the difference of their tints by the aid of 
appropriate glasses. This apparatus, to which I have given 
the name of the Chromascope, and which is founded 
on the principle of the sextant, has allowed me to 
compare, one with the other, most of the stars visible 
above the horizon of Paris, including the planets, em- 
ploying now and then artificial light to facilitate the compa- 
rison. The results which I have obtained are very curious. 
Thus, for example, a gas-burner seen at 1 kilometre off 
produces — with Sirius in the telescope — a garnet and 
sapphire couple; Mars and TBpi, a red and azure couple; 
Mars and Saturn, a red and green couple ; Saturn and 
Altair, a yellow and blue couple ; the Moon and Sirius, a 
brass- and silver-coloured couple ; Antares and Vega, a red 
and blue couple ; &c. 
These comparisons have enabled me to classify the stars 
in a decreasing order of colour, beginning with red. Here 
are some examples - 
1. fi of Cephi . 
2. Lighting gas 
3. Antares . 
4. Mars . . 
5. Mira Ceti 
6. a Herculis 
7. Pollux 
8. Aldebaran 
9. Betelgeuse 
10. Polar star 
11. Capella . 
12. Castor 
13. Jupiter . 
14. Ardturus . 
15. Procyon . 
16. The Moon 
1 7. Rigel . . 
18. Mercury . 
19. Sirius . . . 
20. L’Epi . . . 
VOL. vi. (n.s.) 
Red-orange. 
Orange-red. 
Orange. 
}» 
ff 
Orange-yellow. 
Yellow-orange. 
if 
} 9 
Full yellow. 
Yellow. 
?? 
Creamy yellow. 
Yellowish white. 
White. 
9 1 
99 
K 
