# Natural philosophy. Treatise 2

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### Contents

 NOTICE 2 THE WHEEL AND AXLE 23 THE INCLINED PLANE 30 PRACTICAL MECHANICS 37
 TRANSMISSION OF MOTION 47 FRICTION 63 MODULUS OF MACHINES 71 EXERCISES 89

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Page 73 - When a cubic inch of water is converted into steam at the ordinary pressure of the atmosphere, its volume is increased to 1600 or 1700 cubic inches — that is, a cubic inch of water becomes nearly a cubic foot of steam. If produced under a pressure of two atmospheres, the steam of an inch of water will occupy only half the space, and so of other pressures. When water is boiled in an open vessel, neither the temperature of the water, nor that of the steam rising from it, ever rises higher than 212°,...
Page 45 - T-iron girder, the top and bottom being the two flanges, and the two sides serving to connect them instead of the one rib in the middle. As it is constructed of plateiron, the top requires more metal than the bottom, in order to resist the compression; but instead of putting the metal into one thick plate, or into several plates, laid the one on the other, it is made to form a set of minor tubes or cells, which give additional stiffness and strength to the whole tube. The floor, in like manner, contains...
Page 46 - ... centre will have the greatest power of resistance, and the sum of their moments, or their united effect, will be in proportion to their mean distance from the centre. This mean distance in A is twice that in B ; therefore, the resistance in A is 2 x 4 or 8 times the resistance in B. Generally, the strength of shafts to resist torsion is as the cubes of their diameters.
Page 65 - VIII, leads to the following remarkable conclusion, easily fixing itself in the memory, that with the unguents, hogs* lard and olive oil interposed in a continuous stratum between them, surfaces of wood on metal, wood on wood, metal on wood, and metal on metal, when in motion, have all of them very nearly the same co-efficient of friction, the value of that co-efficient being in all cases included between 0,07 and 0,08, and the limiting angle of resistance therefore between 4° and 4° 35'.
Page 35 - Practically, the screw is never used as a simple machine ; the power being always applied by means of a lever, passing either through the head of the screw or through the nut. The screw therefore acts with the combined power of the ^-^ lever and...
Page 46 - ... weakest point. If a shaft A has twice the diameter of another shaft B, there will be four times as many fibres in the section of fracture of A, to resist the twist, as in that of B. But as the separation takes place by the one end of the fracture...
Page 98 - Woodcuts, haa a neatly engraved Title-page, and is complete in itself. Chambers's Pocket Miscellany. Illustrated with Frontispieces, in 12 Volumes, cloth, price If.
Page 65 - Morin found that with unguents (hog's lard and olive oil) interposed in a continuous stratum between surfaces of wood on metal, wood on wood, and metal on metal, when in motion, have all of them very nearly the same coefficient of friction, being in all cases included between -07 and '08.
Page 75 - ... inches of mercury, or 30 Ibs. on the square inch ; which is shortly expressed by saying, that it has a pressure of two atmospheres. A further rise of 30 inches in the tube would indicate an additional pressure of 15 Ibs., or of three atmospheres in all.
Page 36 - The screw A has a thick round lower extremity B, into holes in which the lever is inserted. This extremity B is attached by a socketjoint to the pressing-table C, so that when the screw is turned in one direction, the table sinks, and when turned in another, the table rises. The books D lie upon a fixed sole S, and are thus between the table and the sole. H is a crosB-beam above, in which is the box or overlapping screw, to give the necessary resistance.