The early civilization in Egypt developed in the ancient cities of Thebes and Memphis. Authorities on the dawn of history in Egypt are unable to definitely account for the origins of the various peoples who have ruled the land. One school contends that the early negroid inhabitants originated in Africa. Another school opposes this view and suggests an Asiatic origin. Each of these schools can marshal facts to sustain its contentions. The truth is that Africa was inhabited at such an early period that we are unable to fully trace back the movements of its races. Man was divided into species and subspecies at a very remote period. The dominant peoples in each country, in each era, were the successful contestants in long conflicts for supremacy. Many races have vanished without leaving any traces beyond reversional strains which still come to the surface at times in families living to-day. The laws of evolution, only recently deciphered, are the sole means we possess for learning about many of the long-perished species of men. A few races, too weak to ever gain supremacy and themselves to occupy districts, or countries, have survived by dwelling among stronger races. The Ainus, in Japan, and the Jews in Asia and Europe, are well-known examples. [Illustration: MODEL OF AN EARLY ELECTRIC MOTOR The original was invented by M. H. Jacobi in 1834 and was used in 1838 to propel a boat on the Neva at St. Petersburg.] [Illustration: MODEL OF AN EARLY TURNING LATHE This mechanism was invented by Thomas Blanchard in 1843. He also invented a lathe for turning gun barrels.] [Illustration: Copyright, Underwood & Underwood AN EDISON PHONOGRAPH OF 1878 The sound record was made on a sheet of tin foil vibrated by the voice.] [Illustration: WHITNEY'S COTTON GIN This device, invented in 1793, revolutionized the cotton and cotton manufacturing industries.] Egypt, owing to its remarkable geographical situation between Asia, Europe, and the vast continent of Africa, has been a great highway for race migrations. Many peoples have lived and ruled there and passed on before incoming tides of new and more vigorous peoples. Each race, undoubtedly, during its residence in Egypt contributed to the general fund of Egyptian knowledge and customs and assisted in the development of science. The tombs of Thebes have given us bodies of ancient Egyptians of more than six thousand years ago. At that time the people were characterized by the Grecian type of profile. They resembled the contemporary active peoples in India and Arabia and did not differ much from the Egyptians of our day. The incoming streams of people who settled in the Nile valley, both Asiatic and negroid, changed the appearance of the Egyptians at different times by intermarriage, but when their vigor waned and they were crowded out by other peoples, the Egyptians assumed their regular Semitic characteristics.