পাতা:পদার্থবিদ্যাসার.djvu/৪৫

34 the north is before you, the south behind you, the east is on your right hand, the west on your left. Pup. Of what use are the winds? Tut. The benefits arising from the winds are almost innumerable; they purify the air, moderate the heat, dry wet lands, and damp houses, chase away the fogs and hazy weather, and bring rain in due season; also frost and snow, and eveu mild weather. They are particularly serviceable for navigation and com Mኽብ£ { {)፥፥. gi Pup. Wlrat is the velocity of wind * - Tut. From one to sixty miles per hour. The motion of wind at one mile per hour is hardly perceptible, while that at sixty miles per hour occasions a greai storm. A common brisk wind travels about fifteen miles an hour; a hurricane which tears up trees, destroys buildings. &c. 100 miles an hour. Pup. ilow many kinds of winds are there? Tut. Three ; the general frade or constant winds, the monsoons or periodical winds, and the sca and land breezes. r Pup. What occasions the general trade winds and the monsoons f Tut. The action of the sun. Pup. How are*ea and iamd breezes occasioned? Pup. As in all maritime countries, the air, during the day, above the land is hotter and more rare than above, the sea, the sea air flows in upon the land, and supplies the place of the rarefied air; and thus the sea breeze is occasioned. Again, as the night approaches, ‘the denser air of the hills and mountains falls down upon the plains, and pressing upon the air of the sea,