stated the interval between the tropics to be 11/83 of the circumference.
Ptolemy used a part of a circle, a quadrant.
It is supposed that Eratosthenes suggested to Ptolemy Euergetes the construction of the large armillae, or fixed circular instruments which were long in use in Alexandria.
Eratosthenes of Cyrene was born B. C. 276, and left Athens at the invitation of P. Euergetes, who placed him over the library in Alexandria, where he remained till the time of P. Epiphanes about B. C. 196.
He is celebrated for his attempt to measure the magnitude of the earth.
He discovered the obliquity of the ecliptic, which he made to be 23° 51′ 20″. He ascertained that Syene in Upper Egypt (lat.
24° 10′N.) was in the tropic, a vertical gnomon casting no shadow at noon on the day of the summer solstice, and thence determined its latitude to be equal to the obliquity of the ecliptic.
Observations at Alexandria determined the zenith of that place to be distant 1/50 part of the circumfere
nclude them in Asia.
The eastern border of the land, abutting upon Libya, was for a time adopted.
Afterwards the Tanais and the Nile were the limits of Asia, one half of Egypt being ascribed to Africa.
Herodotus considered it absurd to divide the country of one people between two continents.
Ptolemy, the geographer, defined the Red Sea and the Isthmus of Suez as the boundary between the continents.
Next is the map of the world according to Eratosthenes and Strabo.
Eratosthenes (276-196 B. C.) of Alexandria was the discoverer of the obliquity of the ecliptic, and was the founder of geodesy.
He determined the circumference of the earth by measuring a degree of the meridian.
Measurements of an are of the meridian have been made by the Chaldeans, by Eratosthenes, by Al Maimon, by Pire, and more lately by the French, English, Germans, and others; in Peru, Lapland, British India, and elsewhere.
(See armil ; armillary-sphere ; astronomical instruments ; odometer.) We regard Eratos
m, Samaria, the land of Moab, Cilicia, and Cyprus.
It disproves the assertion of Aristotle and Pliny that Cadmus only brought 16 or 18 letters from the East into Greece, and that the Greeks invented the rest, for the whole of the 22 are found on this monumental stone.
The Rosetta stone is of 700 years later date.
It was found in 1798 by a French engineer in digging the foundations for a fort near the Rosetta mouth of the Nile.
It is a tablet of basalt, with an inscription of the year 196 B. C., during the reign of Ptolemy Epiphanes.
The inscription is in hieroglyphic, demotic, and Greek.
It was deciphered by Dr. Young, and formed the key to the reading of the hieroglyphic characters.
It was captured by the English on the defeat of the French forces in Egypt, and is now in the British Museum.
The hatchet, mallet, chisel, square, and saw, all occur among the hieroglyphic characters.
i, Fig. 3612, shows small portions of the hieroglyphic and demotic inscriptions, respect