SECT. XII. WEIGHTS AND MEASURES. 89 



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 circumstance concurs in showing that 

 astronomy was cultivated 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 applica- 

 tion 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 configuration of the heavens at the time of its con- 

 struction. 



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. 

 The 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. 154), 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 measure, which is the ten-millionth part of the 

 arc of the meridian which extends from the equator to the pole, 

 as deduced from the measures of the separate arc extending from 

 Formentera, the most southern of the Balearic Islands, to Dun- 

 kirk. Should the national standards of the two countries ever 

 be lost, both may be recovered, since they are derived from 

 natural and invariable ones. The length of the measure deduced 

 from that of the pendulum would be found again with more 



