ASTRONOMY. 351 



sun would then appear to be a mere star itself; while the whole 

 solar system would, if visible, seem to occupy less space than the 

 evening star does to us. 



The study of Astronomy, properly comprehends an investigation 

 of the shape and dimensions of the earth. This has been found, by 

 measuring, in various places, a degree of the meridian ; from which 

 the circumference of the earth, being 360, may be readily calcu- 

 lated ; and from this we obtain its diameter. The diameter of the 

 earth, thus found, becomes a basis, from which the distance to the 

 sun is ascertained, by ascertaining the angular difference of direction 

 in which that luminary would appear, to observers on opposite sides 

 of the earth. In like manner, the distance from the earth to the sun 

 being known, becomes a basis, by which the distance of the fixed 

 stars is found to exceed a certain limit ; although so great that it 

 cannot be exactly measured. The uses of Astronomy, are as import- 

 ant, as its discoveries have been surprizing: and both have prompted 

 its votaries to new and persevering researches. It is especially in 

 its services to Navigation, that Astronomy has aided in extending the 

 progress of discovery ; encouraging commercial enterprize, and dif- 

 fusing the lights of civilization and Christianity around the habitable 

 globe. 



Astronomy is a science doubtless of the highest antiquity. Jose- 

 phus speaks of a period of 600 years, called the grand year, as being 

 known to the Antediluvians, according to the Jewish tradition : and 

 it is certain that the Egyptians and Chaldeans paid great attention to 

 the stars, in connection with their favorite study of astrology, or 

 divination by means of celestial phenomena. Ancient writers state 

 that when Babylon was taken by Alexander the Great, astronomical 

 records were found there, extending back 1903 years, or to the year 

 2234 B. C. : but the earliest eclipses authentically recorded, are those 

 observed at Babylon, 720 and 718 B. C. The origin of Astronomy 

 has also been attributed to the Indians, and Chinese ; but we think 

 without sufficient proof. The Sothic period, of the Egyptians, was 

 one of 1460 years, in which their months returned to the same day 

 of the year ; and the Saros, of the Chaldeans, corresponded to the 

 Metonic or lunar cycle, (p. 200). 



The Greeks derived some knowledge of Astronomy from Egyp- 

 tian, and perhaps Phoenician colonies ; but Thales was the first 

 among them who observed the solstices, and calculated eclipses. 

 Anaximander discovered the sphericity of the earth ; and Pythagoras 

 first taught the true doctrine of the Solar system : but he confined 

 this knowledge to his disciples; and it does not appear to have pre- 

 vailed, at any time, among the ancients. Meton discovered the 

 Metonic orjunar cycle, of nearly 19 years ; at the end of which the 

 sun and moon return to nearly the same position, in relation to the 

 earth. Eratosthenes first measured an arc of the meridian, and 

 deduced the circumference of the earth : and to Hipparchns we are 

 indebted for the earliest catalogue of the stars ; and for the invention 

 of latitude and longitude, to define their position. Ptolemy retarded 

 the science of Astronomy, by maintaining that the earth is at rest, 

 and that the sun and planets revolve around it, as a centre ; but his 



