"Several canals!" exclaimed Frank. "Not several canals at once?" [Illustration: A LANDING-PLACE ON THE FRESH-WATER CANAL.] "Hardly that," said the Doctor, with a smile; "but at different times there have been canals between the two seas. They differ from the present one in one respect: the maritime Canal of to-day runs from one sea to the other, and is filled with salt-water, while the old canals connected the Nile with the Red Sea, and were constantly filled with fresh-water. The Fresh-Water Canal of to-day follows the line of one of the old canals, and in several places the ancient bed was excavated and the ancient walls were made useful, though they were sadly out of repair." One of the boys asked how old these walls were, to be in such a bad condition. "We cannot say exactly how old they are," was the reply, "and a hundred years or so in our guessing will make no difference. According to some authorities, one of the rulers of ancient Egypt, Rameses II., conceived and carried out the idea of joining the two seas by means of the Nile and a canal, but there is no evidence that the work was accomplished in his time. The first canal of which we have any positive history was made by Pharaoh Necho I. about 600 B.C., or nearly twenty-five hundred years ago. It tapped the Nile at Bubastis, near Zagazig, and followed the line of the present Fresh-Water Canal to the head of the Bitter Lake. The Red Sea then extended to the Bitter Lake, and the shallow places were dredged out sufficient to allow the passage of the small craft that were in use in those days. The canal is said to have been sixty-two Roman miles long, or fifty-seven English ones, which agrees with the surveys of the modern engineers. "This canal does not seem to have been used sufficiently to keep it from being filled by the drifting sand, as it was altogether closed a hundred years later, when it was re-opened by Darius; the latter made a salt-water canal about ten miles long near the south end of the Bitter Lake, to connect it with the Red Sea. Traces of this work were found when the Fresh-Water Canal was made, and for some distance the old track was followed. Under the arrangement of the canals of Necho and Darius, ships sailed up the Nile to Bubastis, and passed along the canal to the Bitter Lake, where their cargoes were transferred to Red Sea vessels. About 300 B.C. Ptolemy Philadelphus caused the two canals to be cleared out, and connected them by a lock, so that ships could pass from the fresh to the salt water, or _vice versa_. [Illustration: ORIENTAL SHIPS OF ANCIENT TIMES.]