. Haswell's engineers' and mechanics' pocket-book ... ^ko °^ ^^^^ result for each degree which the mean temperature of the air at the two stations exceeds 550, and deduct as muchlor each degree below 5oO. *vi* Velocity and Force of Wind. Miles in anhour. Feet in aminute. 1 • 88 2 176 3 264 4 352 5 440 6 528 8 704 10 880 15 1320 20 1760 25 2200 30 2640 35 3080 40 3520 45 3960 50 4400 60 5280 80 7040 100 8800 Pressure on a squarefoot in pounds avoir-dupois. . ).045 ]. ) ] ) ) ) ] Description. Barely o
. Haswell's engineers' and mechanics' pocket-book ... ^ko °^ ^^^^ result for each degree which the mean temperature of the air at the two stations exceeds 550, and deduct as muchlor each degree below 5oO. *vi* Velocity and Force of Wind. Miles in anhour. Feet in aminute. 1 • 88 2 176 3 264 4 352 5 440 6 528 8 704 10 880 15 1320 20 1760 25 2200 30 2640 35 3080 40 3520 45 3960 50 4400 60 5280 80 7040 100 8800 Pressure on a squarefoot in pounds avoir-dupois. . ).045 ]. ) ] ) ) ) ] Description. Barely breeze. Gentle, pleasant wind. Brisk wind. Very high. Storm. Great storm. Hurricane. Tornado, tearing up trees, &c. To find the Force of Wind acting perpendicularly upon aSurface. the surface in feet by the square of the velocityin feet, and the product by .002288 ; the result is the force in avoir-idupois pounds. Q 182 STATICS. STATICS. PRESSTJRE OF EARTH AGAINST B. 1j I^ ^ . Let AB C D be the vertical section of a wall, behind which is abank of earth, AD/.; let DG be the line of rupture, or naturalslope which the earth would assume but for the resistance of thewall. - In sandy or loose earth, the angle G D H is generally 30«; in firmerearth it is 36°, and in some instances it is 45°. The angle formed with the vertical by the earth, AD G that ex-erts the greatest horizontal stress against a wall, is half the anglewhich the natural slope makes with the vertical. If the upper surface of the earth and the wall which supports itare both in one horizontal plane. Then the resultant In of the pressure of the bank, behind a verti-eal wall, is at a distance D w of J A D. In ve^retable earths, the friction is J the pressure ; in sands, ^. The tine of rupture A G in a bank of vegetable earth is = .618 of A D. When the bank is of sand, it is .677 of A D. If of rubble, it is .414 of A D. Thichiess of Walls,
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Keywords: ., bookcentury1800, bookdecade184, booksubjectmechanicalengineering
