OPTICAL NOMENCLATURE OF COLOURS, 
for Double-Star Observers and Others. 
Be eee eee 
ECTRUM. or PURE. NATURAL AND ORIGINAL SOLAR-SPECTRUM COLOURS. 
MIDDLE OF SPECTRUM. — 








VIOLET-END 
| | 






50000 




47000 | 50000 




58000 
60000 






| ] 
Orange |Amber.| | Yellow. CITRON) 
eel 

Scarlet. 












Lavender Gray. |) 

Indigo. | | VIOLET. 



Lightest. 
ey, 
i] 








36000459000. 


PULL 


COLOUR. 

LILAC | PURPLE. | Red-Gray- 

: 




Yell-Gray. 
——— 
Ey 

6000 
46000and 
59000. 
ay 










Black-Uray. 

Blue-Gray. 


