810 PROFESSOR PIAZZI SMYTH ON COLOUR, 
GREEN GLASS—continued. 










TWO GREEN GLASSES INTERCEPT. 
Intensity, 7 Wave-number | Colour Region by 
Max. =10. 4 in Brit. inch. | Wave-number. 
First brown red light : : ; , 0-1 25°730 | 41 806 | AMBER 
Strong brown red light . ; ‘ ; 2:0 25°820 | 42 735 | AMBER 
Brown red ends, gray begins. : : 4:7 25°960 | 44 405 | YELLow 
Maximum Licut ; 5 : : 4 50 26050 | 45 310 | Cirron 
Grass green colour. : : ; : 4:0 26:270 | 47 281 | GREEN 
Green black begins . ; ' : ; 16 26570 | 50 000 | GLAucous 
Endall . : : : ; é : 0:0 26°820 | 51 813 | GLAucouUS 
FOUR GREEN GLASSES INTERCEPT. 
First light seen . : : ; : } 0-0 25930 | 44 111 | YELLow 
Decided light . : ‘ z : : 0-4 25°975 | 44 563 | YELLOW 
End of shade. ; : ‘ : : 15 26070 | 45 455 | Crrron 
Maximum LIGHT : : : 3 ; 2:0 26140 | 46 147 | CiTRoN 
Dark grass green begins. : : ; 16 26295 | 47 619 | GREEN 
Very dark . ' : : : d : 0-4 26530 | 49 677 | GREEN 
Endall_ . ; : : : : : 0:0 26675 | 50 839 | GLAUCcoUS ha 


Eight green glasses show only the ghost of a band in or near 46,990 Wave N*. Green 
glass is almost as much of an obscurer as transmitter; and what it transmits is a very broad 
band between, and also including, both Dand E. This being the brightest part of the spectrum, 
ereen glass is not often wanted in Spectral Observations, to promote the transmission of that 
coloured light, and retard, or prevent, the transmission of all other colours. 
COBALT-BLUE GLASS. 










COAL-GAS FLAME’S CONTINUOUS SPECTRUM (RepEArTEeD). 
; Intensity, i Wave-number | Colour Region by 
Max. =10. : in Brit. inch. | Wave-number. 
False glare from internal reflections . : 05 24-642 | 26 596 | Ultra Rep 
True but faint black-red light . ; : 0°3 24:965 | 30 864 | Crimson RED 
Strong red light seen at. , ‘ : 30 25:145 | 34 305 | Crimson RED 
D slit, red side thereof : ; ; : 9:0 25°3823 | 42 827 | AMBER 
»  yellowside . : é p : 9°3 25°873 | 43 384 | YELLOW 
Maximum Licut : : : s ; 9:5 25940 | 44 053 | YELLow 
Green light ends, blue beginsat . .| 90 | 26220] 46 948 | Crrron 
Blue light ends, violet light begins. ; 3:0 26°670 | 58 140 | InpIcGo 
All light ends at : ; 5 0-0 28430 | 64 516 | LAVENDER 




