A System of Natural Philosophy: In which the Principles of Mechanics, Hydrostatics, Hydraulics, Pneumatics, Accoustics, Optics, Astronomy, Electricity, Magnetism, Steam Engine, and Electro-magnetism, are Familiarly Explained, and Illustrated by More Than Two Hundred Engravings ;to which are Added, Questions for the Examination of Pupils; Designed for the Use of Schools and Academies

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Robinson, Pratt, & Company, 1813 - Physics - 340 pages

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Page 161 - The circumference of every circle is supposed to be divided into 360 equal parts called degrees, and each degree into 60 equal parts called minutes, and each minute into 60 equal parts called seconds, and these into thirds, fourths, &c.
Page 171 - Different opinions have been advanced by astronomers respecting the cause of these appearances. By some, they have been regarded as clouds, or as openings in the atmosphere of the planet, while others imagine that they are the marks of great natural changes, or revolutions, which are perpetually agitating the surface of that planet. It is, however, most probable, that these appearances are produced by the agency of some cause, of which we, on this little earth, must always be entirely ignorant.
Page 121 - Lens is a transparent body, generally made of glass, and si shaped that the rays of light in passing through it are either collected together or dispersed. Lens is a Latin word, which comes from lentile, a small flat bean. It has already been shown, that when the rays of light pass from a rarer to a denser medium, they are refracted, or bent out of their former course, except when they happen to fall perpendicularly on the surface of the medium.
Page 23 - Thus, a tall body, shaped like fig. 27, will fall, if it. leans but very slightly, for the centre of gravity being far above the base, at a, is brought over the centre of motion, b,with little inclination, as shown by the plumb line.
Page 211 - The moon always presents the same face to us, by which it is evident that she turns but once upon her axis, while she performs a revolution round the earth ; so that the inhabitants of the moon have but one day and one night in the course of a lunar month. Since we always see the same hemisphere of the moon, the inhabitants of that hemisphere alone can see the earth.
Page 251 - M or Q, according to the position of the magnetic poles, or the direction of the current, as already explained. In either case it is thrown out of the mercury, and the galvanic circuit being thus broken, the effect ceases until the wire falls back again by its own weight, and touches the mercury, when the current being again perfected, the same influence is repeated, and the wire is again thrown away from the mercury, and thus the vibratory motion becomes constant.
Page 236 - The friction of the rubber against the glass plate (or cylinder) produces a transfer of the electric fluid from the rubber to the plate ; that is, the cushion becomes negatively and the glass positively electrified. The fluid which thus adheres to the glass, is carried round by the revolution of the cylinder ; and its escape being prevented by the silk...
Page 161 - The names of the 12 signs of the zodiac are, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. The...
Page 69 - ... completed, when a more awful hurricane burst upon them than the most experienced had ever braved. Nothing could withstand it; the sails already furled and closely bound to the yards, were riven away in tatters; even the...
Page 139 - REFRACTING TELESCOPE. — The most simple refracting telescope consists of a tube, containing two convex lenses, the one having a long, and the other a short, focal distance. (The focal distance of a double convex lens, it will be remembered, is nearly the centre of a sphere, of which it is a part.) These two lenses are placed in the tube, at a distance from each other equal to the sum of their two focal distances. Fig.

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