Sir John Lubbock’s Address. 851 
considerations, it would seem, therefore, that the three primary 
colors —if such an impression be retained :-—are red, green, 
and violet. 
chemical action. Stokes, however, showed in 1852 that their 
existence might be proved in another manner, for that. there 
are certain substances which, when excited by them, emit light 
visible to our eyes. ‘To this phenomenon he gave the name of 
fluorescence. At the other end of the spectrum, Abney has 
recently succeeded in photographing a large number of lines 
in the infra-red portion, the existence of which was first proved 
by Sir William Herschel. 
rom the rarity, and in many cases the entire absence, of 
reference to blue, in ancient literature, Geiger — adopting and 
our ancestors were blue-blind. Though for my part I 
ymns to heaven, nor the Zendavesta, the Bible of the Parsees 
or fire-worshippers, nor the Old Testament, nor the Homeric 
eep, an 
there, modulated by the filmy, formless body of th 
. 
akg vapor, till it is lost imperceptibly in its crimson an 
go ” 
very minute particles suspended in water are blue by reflected 
light. Tyndall has taught us that the blue of the sky is due 
to the reflection of the blue rays by the minute particles float- 
tng in the atmosphere. Now if from the white light of the 
sun the blue rays are thus selected, those which are transmitted 
will be yellow, orange and red. Where the distance is short 
