OBSERVATION OF LIGHT. 13tf 



and certainly the easiest of all observation: and 

 thus, with a knowledge of some of the best known 

 and most obvious principles, any man who chooses 

 may derive his full measure of enjoyment from it. 

 Cloud or no cloud, the light on the scene changes 

 its appearance every hour ; and there is a gradual 

 change throughout the seasons. In the spring, the 

 red and the oxydizing heat, as well as the fading of 

 the blue into the violet tints, and the deoxydizing 

 energy of that end of the spectrum, are busily at 

 work in bringing forward all the young leaves of the 

 year ; so that the yellow and the blue are sent back 

 to refresh the eye with the lovely green the indi- 

 cator of the greatest action in the n*ajority of vege- 

 tables. Thus, when the plants of the season and 

 the annual shoots of the trees have attained their 

 full size, and the seeds of the future successions are 

 about to be prepared, the oxydizing action becomes 

 less in the delicate texture of the flowers ; and most 

 of their petals absorb chiefly either the yellow or 

 the blue, so that they seldom give back the green. 

 The colours approximate to the golden yellow, the 

 orange, and the intense red, in proportion to the 

 warmth of the climate and the year, and also to the 

 advanced heat of the season. Few early plants 

 have red flowers, though some of them are tinted 

 with pink. In cold places, also, there are not many 

 of the flowers red, while the little ones on the stony 

 and warm moors, even at considerable elevations, 

 are of that colour. Tropical vegetation, on the 

 other hand, is rich in scarlet and gold, and the tints 

 of the flowers of early autumn are the richest in 

 the whole season. Autumn is rich in hues for a 

 while ; but they are, like the hectic flush on the 

 cheeks of the consumptive, the signs of dissolution, 

 and when they have passed the dingy hue of winter 

 is put on. In the northern regions, the snow serves 

 as a mantle to cover the earth, and suspends all 

 action between its surface and the sun, while the 



