100 WEIGHTS AND MEASURES. [SECT. xn. 



Eudoxus, a contemporary of Plato, mentions a star situate in 

 the pole of the equator, and it appears from computation 

 that * Draconis was not very far from that place about 3000 

 years ago ; but, as it is only about 2150 years since Eudoxus 

 lived, he must have described an anterior state of the 

 heavens, supposed to be the same that was mentioned by 

 Chiron about the time of the siege of Troy. Thus every cir- 

 cumstance concurs in showing that astronomy was culti- 

 vated in the highest ages of antiquity. 



It is possible that a knowledge of astronomy may lead to 

 the interpretation of hieroglyphical characters. Astronomical 

 signs are often found on the ancient Egyptian monuments, 

 probably employed by the priests to record dates. The author 

 had occasion to witness an instance of this most interesting 

 application of astronomy, in ascertaining the date of a 

 papyrus, sent from Egypt by Mr. Salt, in the hieroglyphical 

 researches of the late Dr. Thomas Young, whose profound 

 and varied acquirements do honour to his country, and to 

 the age in which he lived. The manuscript was found in a 

 mummy case ; it proved to be a horoscope of the age of 

 Ptolemy, and its date was determined from the configura- 

 tion of the heavens at the time of its construction. 



The form of the earth furnishes a standard of weights 

 and measures for the ordinary purposes of life, as well as for 

 the determination of the masses and distances of the heavenly 

 bodies. Th^ length of the pendulum vibrating seconds of 

 mean solar time, in the latitude of London, forms the standard 

 of the British measure of extension. Its approximate length 

 oscillating in vacuo at the temperature of 62 of Fahrenheit, 

 and reduced to the level of the sea (N. 150), was determined 

 by Captain Kater to be 39-1393 inches. The weight of a 

 cubic inch of water at the temperature of 62 of Fahrenheit, 

 barometer 30 inches, was also determined in parts of the 

 imperial troy pound, whence a standard both of weight and 

 capacity was deduced. The French have adopted the metre 

 equal to 3*2808992 English feet for their unit of linear 



