Curiosities of Science. 147 



UNIVEKSALITY OF THE ATMOSPHERE. 



It is only the girdling, encircling air that flows above and 

 around all that makes the whole world kin. The carbonic acid 

 with which to-day our breathing fills the air, to-morrow makes 

 its way round the world. The date- trees that grow round the 

 falls of the Nile will drink it in by their leaves ; the cedars of 

 Lebanon will take of it to add to their stature ; the cocoa- 

 nuts of Tahiti will grow rapidly upon it ; and the palms and ba- 

 nanas of Japan will change it into flowers. The oxygen we are 

 breathing was distilled for us some short time ago by the mag- 

 nolias of the Susquehanna; the great trees that skirt the Ori- 

 noco and the Amazon, the giant rhododendrons of the Hima- 

 layas, contributed to it, and the roses and myrtles of Cashmere, 

 the cinnamon-tree of Ceylon, and the forest, older than the 

 Flood, buried deep in the heart of Africa, far behind the Moun- 

 tains of the Moon. The rain we see descending was thawed 

 for us out of the icebergs which have watched the polar star 

 for ages ; and the lotus-lilies have soaked up from the Nile, and 

 exhaled as vapour, snows that rested on the summits of the 

 Alps. North-British Review. 



THE HEIGHT OF THE ATMOSPHF.KE. 



The differences existing between that which appertains to 

 the air of heaven (the realms of universal space) and that which 

 belongs to the strata of our terrestrial atmosphere are very 

 striking. It is not possible, as well-attested facts prove, per- 

 fectly to explain the operations at work in the much-contested 

 upper boundaries of our atmosphere. The extraordinary light- 

 ness of whole nights in the year 1831, during which small print 

 might be read at midnight in the latitudes of Italy and the north 

 of Germany, is a fact directly at variance with all we know 

 according to the researches on the crepuscular theory and the 

 height of the atmosphere. The phenomena of light depend 

 upon conditions still less understood ; and their variability at 

 twilight, as well as in the zodiacal light, excite our astonish- 

 ment. Yet the atmosphere which surrounds the earth is not 

 thicker in proportion to the bulk of our globe than the line of 

 a circle two inches in diameter when compared with the space 

 which it encloses, or the down on the skin of a peach in com- 

 parison with the fruit inside. 



COLOURS OF THE ATMOSPHERE. 



Pure air is blue, because, according to Newton, the mole- 

 cules of the air have the thickness necessary to reflect blue rays. 

 When the sky is not perfectly pure, and the atmosphere is 

 blended with perceptible vapours, the diffused light is mixed 



