808 PROFESSOR PIAZZI SMYTH ON COLOUR, 
YELLOW-BROWN GLASS. 





COAL-GAS FLAME’S CONTINUOUS SPECTRUM (REPEATED). 
Intensity, a ‘Wave-number | Colour Region by 
Max. =10. ° in Brit. inch. Wave-number. 
False glare from internal reflections . — . 0°5 24642 | 26 596 | Ultra Rep 
True but faint black-red light . : : 0°3 24°965 | 30 864 | Crimson RED 
Strong red light seen at. Oe 52 ; 30 25145 | 34 305 | Crimson Red | 
D slit, red side thereof ; : ; : 9-0 25°823 | 42 827 | Amber 
»  yellowside . : : : : oe 25°873 | 43 384 | YELLOW 
Maximum Licut ; é : : ‘ 95 25°940 | 44 053 | YELLOW 
Green light ends, blue begins at , J 9-0 26220 | 46 948 | Crrron 
Blue light ends, violet light begins. : 3:0 27670 | 58 140 | Vielet 
All light ends at Ee : : 0-0 28'430 | 64 516 | LAVENDER 


ONE YELLOW-BROWN (ANTI-PHOTOGRAPHIC) GLASS INTERCEPTS (t=63°). 




Red false glare in this region. : : 02 24500 | 23 585 | UltraRed | 
True red light begins : : : 5 03 24960 | 31 348 | Crimson Red | 
Strong red light Ms og WEBS Oh, ae 12 | 25:090 | 33 422 | Crimson Red | 
Stronger ’ : s ; : 21 25170 | 34 722 | Crimson Red 
Very ‘strong red light : : : 4:0 25°280 | 36 697 | Rep 
Chief Red light . , b : ; : 72 25°730 | 41 806 | AMBER 
Maximum YELLow Licut . : . 74 25°830 | 42 974 | Amber 
Green light begins. , ; ; ; 7:0 25°980 | 44 643 | YELLOW 
Grass green : : z ; : : 61 26:260 | 47 259 | GREEN 
Dark green : : 3 52 26480 | 49 188 | GREEN 
Green-black and false violet shade : 37 26690 | 50 942 | GLAucoUS 
Blue-black colour. 14 27:035 | 53 476 | GLAUCoUS 
End of all true light, but not of false glare 0°5 27390 | 56 101 | BLUE 
Faint false glare ends , : ; 0-0 28°350 | 63 939 - | LAVENDER 

TWO YELLOW-BROWN GLASSES INTERCEPT. 



False glare begins nearly . : =e 0:3 24550 | 24 814 | Ultra Rep 
First true red light. ! : , ‘ 0:3 24:910 | 30 581 | Crimson RED 
Strong red light : A : : : 1:0 =| 25:040 | 32 680 | Ultra Crim- 
son RED 
Stronger . : : ; : ‘ : 2:2 25198 | 35 248 | Rep 
Very strong. : : 34 25:°270 | 36 364 | Rep 
Red up to this, the eee LIGHT . ; 6-4 25:820 | 42 735 | Amber 
Yellow-green light begins . : : : 6:2 25°884 | 43 554 | YELLOW 
Grass green : : ; : : : 37 26:220 | 46 948 | CrTRon 
Black green : 14 26°420 | 48 709 | GREEN 
End of all true light, but not of false glare 0-4 26°625 | 50 378 | GLAucoUS 
_ Ultra false glare ends : 0:0 26°950 | 52 798 | GLaucous 




