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angle apparatus applied atmosphere attraction axis axle ball beam body center of gravity centrifugal force charge chromatic aberration colors column common concave concave lens condensed consequently convex lens cylinder diameter diminished direction earth effect elasticity electricity electrified electrometer equal equilibrium example experiments eye-glass fall feet figure fluid focal distance focus force friction fulcrum glass greater Hence horizontal inches inclined plane increased instrument insulated iron lenses less lever Leyden Jar light machine magnet means mechanical microscope mirror motion move Natural Philosophy needle north pole object object-glass opposite orifice passing pendulum perpendicular piston placed pole portion pressure prime conductor principle produced properties pulley quantity quicksilver Reflecting Telescopes reflexion refracting resistance rest retina revolve screw side sound space spark specific gravity spherical aberration steam supposed surface telescope tion tricity tube valve velocity vessel vibrations weight wheel wind
Σελίδα 138 - When the pipe AD is filled with water, the pressure upon the surface of the bellows, and consequently the force with which it raises the weights laid on it, will be equal to the weight of a cylinder of water, whose base is the surface of the bellows, and height that of the column AD. Therefore, by making the tube small, and the bellows large, the power of a given quantity of water, however small, may be increased indefinitely. The pressure of the column of water in this case corresponds to the force...
Σελίδα 69 - Mechanical powers are six, viz : the lever, the wheel and axle, the pulley, the inclined plane, the screw, and the wedge.
Σελίδα 148 - A very slight declivity suffices to give the running motion to water. Three inches per mile, in a smooth straight channel, gives a velocity of about three miles per hour. The Ganges, which gathers the waters of the Himalaya mountains, the loftiest in the world, is, at eighteen hundred miles from its mouth, only eight hundred feet above the level of the sea — that is, above twice the height of St.
Σελίδα 100 - The pulley is a small wheel, movable about its axis by means of a cord, which passes over it. When the axis of a pulley is fixed, the pulley only changes the direction of the power ; if movable pulleys are used, an equilibrium is produced, when the power is to the weight, as one to the number of ropes applied to them.
Σελίδα 68 - ... nor by different degrees of ramming, nor by firing the charge of powder in different parts of it. But that a very great difference in the velocity arises from a small degree in the windage : indeed with the usual established windage only, viz, about ^ of the calibre, no less than between -j- and £ of the powder escapes and is lost : and as the balls are often smaller than the regulated size, it frequently happens that half the powder is lost by unnecessary windage.
Σελίδα 10 - M any cause which moves or tends to move a body, or which changes or tends to change its motion.
Σελίδα 35 - A man in a boat pulling a rope attached to a large ship, seems only to move the boat: but he really moves the ship a little, for...
Σελίδα 82 - As the diameter of. the axle is to the diameter of the wheel, so is the power applied to the wheel, to the weight suspended on the axle.
Σελίδα 24 - ... speed in pursuit. The hare doubles, that is, suddenly changes the direction of her course, and turns back at an oblique angle with the direction in which she had been running. The greyhound, unable to resist the tendency of its body to persevere in the rapid motion it had acquired, is urged forward many yards before it is able to check its speed and return to the pursuit. Meanwhile the hare is gaining ground in the other direction, so that the animals are at a very considerable distance asunder...