Letters on Astronomy: Addressed to a Lady; in which the Elements of the Science are Familiarly Explained in Connexion with Its Literary History |
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Page 25
... represented there . I do not advise to begin learning the definitions from the globe ; the mind is more improved , and a power of conceiving clearly how things are in Nature is more effectually ac- quired , by referring every thing , at ...
... represented there . I do not advise to begin learning the definitions from the globe ; the mind is more improved , and a power of conceiving clearly how things are in Nature is more effectually ac- quired , by referring every thing , at ...
Page 26
... represent the earth , select a large apple , ( a melon , when in season , will be found still better . ) The eye and ... represent the axis of the sphere . A circle cut around the apple , half way between the poles , will be the equator ...
... represent the earth , select a large apple , ( a melon , when in season , will be found still better . ) The eye and ... represent the axis of the sphere . A circle cut around the apple , half way between the poles , will be the equator ...
Page 27
... represent the prime vertical . Simple as the foregoing device is , if you will take the trouble to construct one for yourself , it will lead you to more correct views of the doctrine of the sphere , than you would be apt to obtain from ...
... represent the prime vertical . Simple as the foregoing device is , if you will take the trouble to construct one for yourself , it will lead you to more correct views of the doctrine of the sphere , than you would be apt to obtain from ...
Page 28
... represent the two tropics and the two polar cir- cles . In fact , all circles whatsoever , which are perpen- dicular to the plane of projection , will be represented by straight lines . But every circle which is perpen- dicular to the ...
... represent the two tropics and the two polar cir- cles . In fact , all circles whatsoever , which are perpen- dicular to the plane of projection , will be represented by straight lines . But every circle which is perpen- dicular to the ...
Page 29
... represents the concave surface of the sphere , A , B , two points on it , as two stars , and C A , CB , straight lines drawn from the spectator to those points , then the angular distance between them is meas- ured by the arc A B , or ...
... represents the concave surface of the sphere , A , B , two points on it , as two stars , and C A , CB , straight lines drawn from the spectator to those points , then the angular distance between them is meas- ured by the arc A B , or ...
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Common terms and phrases
angle appear ascertain astronomers atmosphere attraction axis called celestial centre circle comet conjunction constellation degrees diameter direction discovery disk distance diurnal motion doctrine double stars earth ecliptic equal equator equinox exhibited fact fixed stars force Galileo globe gravity greater greatest half Halley's comet heavenly bodies heavens Hence Herschel horizon hundred inferior conjunction instrument John Herschel Jupiter Kepler latitude laws length less light longitude lunar lunar eclipse magnitude measure Mercury meridian meteors millions of miles minutes moon moon's motion move Nature nearer nearly node objects observations opposite orbit parallax passing perihelion period phenomena planetary planets pole respect revolve right ascension ring round satellites Saturn seen shadow side space spectator sphere sun's superior planets supposed surface telescope thousand tides tion truth Tycho Tycho Brahe universal gravitation Uranus velocity Venus vernal equinox visible west to east