[Frost and fire : natural engines, tool-marks and chips : with sketches taken at home and abroad by a traveller] . w. We have but to look above us to read some of the ancientcharacters, which are and have been written in air, and tolearn their meaning. They are forms which reveal a calm clear summer evening, after a thunder shower,when the setting sun is near the horizon, and the wind isstill, great masses of vapour often pile themselves up mtofantastic shapes which can only be seen in profile from a dis-tance. They are easily drawn, and easily to the eastward shin
[Frost and fire : natural engines, tool-marks and chips : with sketches taken at home and abroad by a traveller] . w. We have but to look above us to read some of the ancientcharacters, which are and have been written in air, and tolearn their meaning. They are forms which reveal a calm clear summer evening, after a thunder shower,when the setting sun is near the horizon, and the wind isstill, great masses of vapour often pile themselves up mtofantastic shapes which can only be seen in profile from a dis-tance. They are easily drawn, and easily to the eastward shine like snow in the evening sim-light, and their shapes are clearly defined by light andshadow. Those to the west are dark, or edged witl) brilliantlight, and their outlines cut sharply against tlie western sky. Such clouds float steadily in the air ; they are unaltered by ATMOSPHERIC FORMS. 23 wind ; but when they are closely watched, they are seen tochange their forms at every instant. There are magazines of force within them and without,and changing forms point out the directions in which theseforces act. \. Fi,. .j. Diagram lo thk Growih hf a Cloud, The outlines were traced with a pencil on the ground glass of a camera , on a still, bright, hot evening. Whoever has been enveloped in a mountain mist or a cityfog, knows that a cloud is commonly made up of minutefloating spheres of water, and these are moved about l)y currentsof air, which are moved by some force. 24 ATMOSPHERIC FORMS. These liquid spheres form at one place and disperse atanother, according to the temperature and humidity of the airabout them; but while they exist as drops in clouds theycollect and scatter, and move according to movements of theair in which they float. Clouds are but fleeting characterswritten in air ; but while they endure, they tell their story bytheir form and by their movements. In order to see thesecloud-forms, and note changes which take place in them, theymust be
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