=4. Decipherment.=--One of the objects found by the French at the time of Napoleon’s expedition was the “Rosetta Stone,” so called because found at Rosetta (_Ar-Rashid_), a town near the mouth of the westernmost of the large branches of the Nile. This stone was set up about 200 B. C. by some priests, who expressed, through the inscription which it bore, their thanks to the young king, Ptolemy V, because certain taxes formerly imposed on them had been remitted. The inscription was written in three kinds of writing--hieroglyphic Egyptian (picture-writing), demotic Egyptian (developed from picture-writing), and Greek; (see Fig. 14). It was among the objects which the English took in 1802, and had been placed in the British Museum. Although the Greek portion of the inscription could be easily read, the attempts of various scholars, through a period of twenty years, had succeeded in establishing the values of only a few characters of the Egyptian. In 1818 Jean François Champollion, a French scholar, who before this had busied himself with the study of Coptic and Egyptian geography, began the study of the Rosetta Stone. He assumed that the language of the upper registers must be an older form of the Coptic tongue. By a most painstaking comparison of the characters in the upper registers with the Coptic equivalents of the words in the lower or Greek register, he succeeded in deciphering the long-forgotten writing of ancient Egypt. He published his discovery in 1822. Thus the door to the historical and literary treasures of ancient Egypt was unlocked, and from that time to this the study of Egyptian inscriptions and documents has gone steadily forward. Many universities now maintain chairs of Egyptology. The ability to read Egyptian has opened up vistas of history of which men had hitherto no conception. =5. Chronology.=--We are dependent for our main outline of Egyptian chronology upon the work of Manetho, an Egyptian priest, who lived about 250 B. C., and wrote a chronicle of his native land in the Greek language. He grouped the kings of Egypt from the time of Menes (or Mena) to the conquest of Alexander the Great (332 B. C.) into thirty-one dynasties. Manetho’s dynasties enable scholars to determine the relative order of the kings, and thus form the backbone of our chronology. Around his statements the discoveries of the excavators and explorers are grouped. Manetho’s work has not, however, come down to us. We know it only through quotations in the _Chronographiai_ of Julius Africanus (221 A. D.) and the _Chronicon_ of Eusebius of Cesarea (265-340 A. D.). The number of years assigned to each king, and consequently the length of time covered by the dynasties, differ in these two copies, so that, while the work of Manetho forms the backbone of our chronology, it gives us no absolutely reliable chronology. It is for this reason that the chronological schemes of modern scholars have differed so widely.