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air-pump angle angle of incidence aperture apparent magnitude appear atmosphere atmospheric pressure attraction axis ball bottom called centre of gravity colours concave concave lens convex lens cord course crystalline lens cylinder diameter diminished direction distance earth effect elastic electricity equal excited experiment eye-glass fall feet filled with water fluid focus force friction glass inches inclined plane instrument iron length lever liquid magnet manner means mercury metallic mirror motion move north pole object observed particles pass perpendicularly person piece piston placed plane plate polarized portion position pounds pressure prime conductor prism produced pulley quantity Quest ray of light reflected refracted represented in figure retina rise screw sealing-wax seen side solid sound south pole space specific gravity spectrum substance suppose surface suspended telescope tion tube usually valve velocity vessel vibrations weight wheel
Page 178 - Why the image is seen as far behind the mirror as the object is in front of it.— Let AB be an arrow held Fig.
Page 85 - With a given base and height, therefore, the pressure is the same whether the vessel is larger or smaller above, whether its figure is regular or irregular, whether it rises to the given height in a broad open funnel, or is carried up in a slender tube. Hence, any quantity of water, however small, may be made to balance any quantity, however great. This is called the hydrostatic paradox.
Page 26 - I shall just offer a few illustrations of the CENTRE OF GRAVITY. The centre of gravity of a body is that point about which all its parts...
Page 80 - The pressure of a liquid on any surface immersed in it is equal to the weight of a column of the liquid whose base is the surface pressed...
Page 56 - Powers, are certain simple instruments, commonly employed for raising greater weights, or overcoming greater resistances, than could be effected by the natural strength without them. These are usually accounted six in number, viz. the Lever, the Wheel and Axle, the Pulley, the Inclined Plane, the Wedge, and the Screw.
Page 183 - When a ray of light passes obliquely from one medium to another of different density, it is refracted or bent out of its course.
Page 60 - The most striking example of levers of the third kind is found in the animal economy. The limbs of animals are generally levers of this description. The socket of the bone is the fulcrum ; a strong muscle attached to the bone near the socket is the power; and the weight of the limb, together with whatever resistance is opposed to its motion, is the weight.
Page 278 - Singer, is made by melting together one ounce of tin and two ounces of zinc, which are to be mixed, while fluid, with six ounces of mercury, and agitated in an iron, or thick wooden box, until cold. It is then to be reduced to...