2 
Proceedings of the Royal Society 
Monday , 3 d December , 1866. 
Sir David Brewster, the President, delivered the following 
Opening Address : — 
Gentlemen, — Of all the agencies which are at work in the mate- 
rial universe, the light of the sun is doubtless the most remarkable, 
whether we study it in its sanitary, its scientific, or its sesthetical 
relations. In the language of metaphor, it is the very life-blood of 
nature, without which everything material would fade and perish ; 
the fountain of all our knowledge of the external universe ; and the 
historiographer of the visible creation, recording and transmitting 
to future ages all that is beautiful and sublime in organic and in- 
organic nature, and stamping on perennial tablets the hallowed 
scenes of domestic life, the ever-varying phases of social intercourse 
and the more exciting scenes of bloodshed and war, which Chris- 
tians still struggle to reconcile with the obligations of their faith. 
The influence of light on physical life is a subject of which we 
know little; but the science of light, which has been studied for 
nearly two centuries by the brightest intellects in the civilised 
world, consists of a body of facts and laws of the most extraordinary 
kind — rich in knowledge, popular and profound, and affording to 
educated students simple and lucid explanations of that boundless 
and brilliant array of phenomena which light creates, and mani- 
fests, and developes. While it has given to astronomy and naviga- 
tion their telescopes and instruments of discovery, and to the bota- 
nist, the naturalist, and the physiologist, their microscopes, simple, 
compound, and polarising, — it has shown to the student of nature 
how the juices of plants and animals, and the integuments and fila- 
ments of organic life, elicit from the pure sunbeam its prismatic 
elements — clothing fruit and flower with their gorgeous attire, 
bathing every aspect of nature in the rich hues of spring and 
autumn, giving to the sky its azure, and to the clouds their gold. 
In treating of the influence of light as a sanitary agent, we enter 
upon a subject almost entirely new ; but admitting the existence 
of the influence itself, as partially established by analogy and 
