790 PROFESSOR PIAZZI SMYTH ON COLOUR, 
Hence in my own practical proceedings touching optical sensations only 
(as in naming double-star colours, which are moreover generally mixtures and 
impure)—I have found it expedient to arrange colours, however made up or 
attained to, in three divisions for eye-reference ; thus— 
(1.) SINGLE-SPECTRUM COLOURS. 

Colours by name, chosen 
during actual spectroscopic 
Principal servations of a high sun The more easily pro- Wave- 
Number.| Divisions ee Lisbon, with 2 large Fixed, black, Solar Lines |Cured of Chemical Flame, pymber place 
: of the dispersion power, a very within the same b gud Heche spats 9 || oases 
Spectrum. narrow slit, no coloured limits. spams or the Inch. 
glasses, yet no side reflec- 
tions or false glare. 












: 000 
1 Z Ultra-Red. x ei a 
2 3 Crimson-Red Y and A Potassium ean 
B rimson-Red, ‘ ss a. 5 000 
3 é RED. wand B. Lithium a. E ae 
2 | 
Zi 7 000 
4 Al Scarlet. C. Scarlet Hydrogen. 9 000 
Qa 
| ca 000 
5 ; a Orange. = Orange Oxygen. (2 0 000 
: Orange-Amber 000 
e ) 2 SBE et | Carbo-hydrogen. a 3 000 
7 3 Yellow D Sodium a ee 
a i } q 5 000 
n 
ry : Citron 5 000 
8 | e CLI ON, Aurora line. | Carbo-hydrogen, e 000 
: | Thallium a, and | (47 000 
9 a | —- Carbo-hydr, G. G. | 0 000 
& 
10 a L Glaucous. F. GlaucousHydrogen. {7 | 
= 
11 a Blue. ie Cesium a and £. | =e oa 
oO 
=) : : : 57 000 
Ps aD Indigo. ye Indigo Nitrogen. { 
: | 8 g 58 000 
: 58 000 
13 Q 4 VIOLET. G. Violet Hydrogen. 
os ye 60 000 
14 Get Lavend Ht! and H? derHyd 60 0a 
EB | avender. and H?. |LavenderHydrogen|) g go9 
a | ‘a 
65 000 
ue 2 Gray: 70 000 | 

