A System of Natural Philosophy: In which the Principles of Mechanics, Hydrostatics, Hydraulics, Pneumatics, Acoustics, Optics, Astronomy, Electricity and Magnetism, are Familiarly Explained ... |
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Page viii
... telescope , 188 162 Gregory's telescope , 189 167 Herschel's telescope , 190 190 192 Concave lens , Vision , Eye , Spectacles , Solar system , Ecliptic , · 206 Day and night , Zodiac , · 206 Seasons of the year , Density of the planets ...
... telescope , 188 162 Gregory's telescope , 189 167 Herschel's telescope , 190 190 192 Concave lens , Vision , Eye , Spectacles , Solar system , Ecliptic , · 206 Day and night , Zodiac , · 206 Seasons of the year , Density of the planets ...
Page 152
... The image of an object appears just as far behind a plane mirror , as the object is before it ; explain fig 129 , and show why this is the case . law , the reflected rays , where they meet the 152 MIRRORS . Telescope, 185.
... The image of an object appears just as far behind a plane mirror , as the object is before it ; explain fig 129 , and show why this is the case . law , the reflected rays , where they meet the 152 MIRRORS . Telescope, 185.
Page 154
... image ? What in a convex mirror ? What is the axis of a convex mirror ? What are diverg . ing rays ? What are converging rays ? The law which governs the passage of light with respect 154 MIRRORS . Convex mirror, Refracting telescope, 186.
... image ? What in a convex mirror ? What is the axis of a convex mirror ? What are diverg . ing rays ? What are converging rays ? The law which governs the passage of light with respect 154 MIRRORS . Convex mirror, Refracting telescope, 186.
Page 185
... Telescope . The telescope is an optical instrument , employ- ed to view distant bodies , and , in effect , to bring them nearer the eye , by increasing the apparent angles under which such objects are seen . These instruments are of two ...
... Telescope . The telescope is an optical instrument , employ- ed to view distant bodies , and , in effect , to bring them nearer the eye , by increasing the apparent angles under which such objects are seen . These instruments are of two ...
Page 186
... telescope has a long , focal distance . Refracting Telescope . The most simple refracting teles- scope consists of a tube , containing two convex lenses , the one having a long , and the other a short , focal distance . ( The focal ...
... telescope has a long , focal distance . Refracting Telescope . The most simple refracting teles- scope consists of a tube , containing two convex lenses , the one having a long , and the other a short , focal distance . ( The focal ...
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Common terms and phrases
appear atmosphere attraction axle ball barometer barrel boat called centre of gravity centrifugal force circle colors concave mirror conductor consequence convergent convex lens convex mirror degrees diameter direction distance earth earth's orbit eclipse elastic electric fluid equal equator equinoxes Explain fig falling body feet fixed stars focus fulcrum glass heat hence illustrated inches inclined plane increased instrument length lenses less lever longitude machine magnetic mercury meridian metals millions of miles moon motion move Natural Philosophy object obliquely orbit particles pass pendulum perpendicular piston plane mirror planets poles position pounds pressure principle proportion pulley pump quantity of matter raised rays of light reflected reflecting telescope refracted respect retina revolution revolve rope screw seen side solar space specific gravity substances sun and clock sun's Suppose surface telescope thrown tion tube turned velocity vessel visual angle weight wheel
Popular passages
Page ii - In conformity to the Act of Congress of the United States, entitled, " An Act for the encouragement of learning, by securing the copies of Maps, Charts, and Books, to the authors and proprietors of such copies, during the times therein mentioned.
Page 206 - 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 215 - 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 285 - ... called the knob of the jar, is made to descend through the cover, till it touches the interior coating. It is along this rod that the charge of electricity is conveyed to the inner coating, while the outer coating is made to communicate with the ground.
Page 255 - 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 205 - Each of the 12 signs of the zodiac is divided into 30 smaller parts, called degrees; each degree into 60 equal- parts, called minutes, and each minute into 60 parts, called seconds.
Page 236 - It will be observed by a careful perusal of the above explanation of the seasons, and a close inspection of the figure by which it is illustrated, that the sun constantly shines on a portion of the earth equal to 90 degrees north, and 90 degrees south from his place in the heavens, and consequently, that he always enlightens 180 degrees, or one half of the earth. If, therefore, the axis of the earth were perpendicular to the plane of its orbit, the days and nights would...
Page 128 - ... came to prepare with all haste for a storm. The barometer had begun to fall with appalling rapidity. As yet, the oldest sailors had not perceived even a threatening in the sky, and were surprised at the extent and hurry of the preparations: but the required measures were not 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 bare...
Page 266 - Latitude is the distance from the equator in a direct line, north or south, measured in degrees and minutes. The number of degrees is 90 north, and as many south, each line on which these degrees are reckoned running from the equator to the poles. Places at the north of the equator are in north latitude, and those south of the equator are in south latitude.
Page 98 - It is evident that the force to be obtained by this principle, can only be limited by the strength of the materials of which the engine is made. Thus, if a pressure of two tons be given to a piston, the diameter of which is only a quarter of an inch, the force transmitted to the other piston, if three feet in diameter, would be...