IN PRACTICAL ASTRONOMY, SPECTROSCOPICALLY EXAMINED. 811 
COBALT-BLUE GLASS—continued. 











ONE COBALT-BLUE GLASS INTERCEPTS. 
Intensity, - Wave-number| Colour Region by 
Max. =10. : in Brit. inch. | Wave-number. 
False glare begins, and the whole spectrum 
tends to bands ; , : ; ‘ 01 24720 | 27 701 | Ultra Rep 
First red true light begins 4 : : 0-2 24:900 | 30 488 | Crimson RED 
Decided red light. ; : ‘ ; 0°6 24970 | 31 447 | Crimson Rep | 
Maximum Rep light band . ; ‘ : 58 25250 | 36 101 | Rep 
Middle of dark shade , ; : : 4:2 25°460 | 38 986 | ScaRLET 
Maximum brown orange light band. ; 5:2 25670 | 41 186 | AmpER 
Middle of a darkish brown band : 5 4:2 25°840 | 43 029 | Yellow 
Maximum of green-yellow light . , : 70 26030 | 45 147 | Crrron 
Green shade begins . ‘ ‘ : : 4:4 26275 | 47 393 | GREEN 
Green ends and blue begins , , : 4:0 26°650 | 50 633 | Glaucous 
Maximum blue light . 5 : , : 5-4 27120 | 54 142 | GuLaucous 
Violet light begins. ; ; : : 38 27620 | 57 971 | Inpico 
End of all light : : : ; 2 0:0 28°370 | 64 144 | LavENDER 




The light transmitted is extravagant in length of spectrum, but distinguished by tendency 
to discontinuous bands chiefly in the red and yellow portions. 

TWO COBALT-BLUE GLASSES INTERCEPT. 










Intensity, | - Wave-number | Colour Region by 
Max. = 10. ‘ in Brit. inch. | Wave-number. 
Light begins at ; : : 0:0 24910 | 30 675 | Crimson RED 
Very decided light is seen aie) : d 0°6 25°010 | 32 206 | Crimson RED 
Maximum of Rep LIGHT . ; : 5 41 25:220 | 35 587 | Rep 
End of red light E A : ; : 2:0 25°360 oF 130 SCARLET 
Middle of dark band . : : ; , 0:8 25°470 | 39 154 | ORANGE 
Maximum Maroon Licut . : : 15 25662 | 41 152 | Amper 
Middle of black-brown shade band . b 0°6 25°860 | 43 253 | YELLOW 
Maximum Green-yellow Licut BAND . : 4:8 26070 | 45 517 | Crrron 
Shade begins. : : : : : 2°5 26170 | 46 468 | Crrron 
Middle of shade : ; ; ‘ 5 1:4 26:°295 | 47 619 Green 
End of shade . : z i ; 1:9 26527 | 49 579 | Green 
Green light ends, blue begins : : : 30 26°810 File Slo Glaucous 
Maxntum BLUE LIGHT 3 ; ; ; 4:0 27080 | 53 735 | Glaucous 
Violet light begins. : : ' : Lf 27720 | 58 824 | VioLET 
End of all light ‘ é : : ; 0:0 28285 | 63 371 | LAVENDER 

