THREE PRINCIPLES OF LIGHT. 47 



to exclaim, Surely the knowledge of the ele- 

 ments, and of the laws which they observe, must 

 comprise all that can be learned of the funda- 

 mental chemistry of creation. 



If we were to ask, Why is this grass so 

 green, that flower so fair in its coloured rai- 

 ment, this gentle air so warm and balmy, and 

 every object around us, glittering with light? 

 we must apply to the sunbeam for an answer, 

 and in the answer we shall find that pervading 

 all nature, and performing the most important 

 part in its operations, there are three distinct 

 principles all united in the sun-ray heat, 

 light, and chemical power, or actinism. Could 

 we break up these bright streams of light which 

 are now pouring down on hill and dale, giving 

 joy, gladness, and life to the scene, into in- 

 dividual rays, and by some process separate one 

 from all the rest, we should find all three in 

 it that is, we should find it to consist of a ray 

 of heat, a ray of light, and a ray of chemical 

 force or actinism, each of these rays being 

 itself made up of several others. A simple ex- 

 periment will prove that these three different 

 classes of rays co-exist in a ray of sunlight. If 

 on a bright summer's day we allow the rays of 

 the sun to pass through a hole into a dark 

 room, and then through a glass prism, we shall 

 find, on holding up a white card a certain dis- 



