The motionless air of winter has been rendered with marvellous truth by John H. Twachtman; the stir of spring by Dwight W. Tryon; the active air of summer by Childe Hassam, and its languorous drowsiness by George Inness. All these are American artists, whom I mention only as examples. For much of the beauty of modern art, both American and foreign, is due to the sensitive rendering of the variations in the atmosphere. For, the best artists now-a-days are not satisfied to paint the features of nature only; they aim to depict the varying expressions on her face. And the chief cause, as I have said, of these variations is the constant change in the conditions of the lighted atmosphere.