1888.] Mr G. N. Stewart on Intermittent Light. 
455 
Experiment 3. — Red light (strong sunlight passed through ruhy- 
red glass). 
Slow S : Green edges, central part golden yellow. 
+ S : Eeddish band appears outside green edges. 
+ S : Reddish band increases in distinctness, and green one 
disappears, the central part becoming redder, and 
finally quite red. 
The light was examined with the spectroscope, and found to he 
very pure. 
Experiment 4. — Red light (weak). 
Here no coloured edges were seen. The image was red with 
every speed. 
Experiment 5. — Red light (stronger than in 4, weaker than in 3). 
Slow S : Whole hand is orange. 
+ S : Edges become tinged with red. 
+ S : Red patches appear in central band. 
+ S : Whole is homogeneous red. 
Experiment 6, — Green light (strong). 
Slow S : Central band white, or faint yellow. Edges purple. 
+ S : Purple edges become blue, and then indigo-blue. 
Central band greenish. 
[At a certain speed can be seen an outer purplish edge, 
and immediately inside this a narrow indigo band j 
while the broad central part is green.] 
+ S : Purple and indigo both disappear, and are replaced by 
a dark green edge — much darker green than that of 
the central part. 
Experiment 7. — Green light (weak). 
Slow S : Edges dark green ; central part lighter green. 
-1- S : Whole image homogeneous green. 
Experiment 8. — Green light (medium intensity). 
Slow S : Central part light green ; outside this a dark green 
band on either side ; and outside this a purple band. 
+ S : Coloured edges disappear. Whole image homogeneous 
green. 
