A line of stakes and buoys extended a considerable distance out into the head of the Gulf, and the Doctor explained that, in consequence of the shallowness near the land, the Suez Canal began more than a mile from the shore. The sand-bar is visible at low tide, and when the wind blows from the north a large area is quite uncovered. A channel was dredged for the passage of ships, and the dredging-machines are frequently in use to remove the sand which blows from the desert or is swept into the channel by the currents. At the end of the long pier is a light-house; and while our friends stood there and contemplated the scene before them, the Doctor reminded the boys that in all probability they were in sight of the spot where the hosts of Pharaoh were drowned after the Israelites had crossed over in safety. "That is very interesting," said Frank; "but is this really the place?" "We cannot be absolutely certain of that," was the reply, "as there are different opinions on the subject. But it was in this neighborhood certainly, and some of those who have made a careful study of the matter say that the crossing was probably within a mile of this very spot." The eyes of the boys opened to their fullest width at this announcement, and they listened intently to the Doctor's remarks on the passage of the Israelites through the Red Sea. "You will remember," said the Doctor, "that the Bible account tells us how the Lord caused a strong wind to blow from the north, which swept away the waters and allowed the Israelites to pass over the bed of the sea. After they had crossed, and the hosts of Pharaoh pursued them, the wind changed, the waters returned, and the army of the Egyptian ruler was drowned in the waves. The rise of the tide at this place is from three to six feet, and the sand-bank is only slightly covered when the tide is out; now, when the wind blows from the north with great force the water is driven away, and parts of the sand-bank are exposed. On the other hand, when a strong wind blows from the south, the water is forced upon the sand-bank, and the tide, joined to this wind, will make a depth of six or seven feet where a few hours before the ground was dry. This is the testimony of many persons who have made careful observations of the Gulf of Suez, and the miracle described in the Bible is in exact accordance with the natural conditions that exist to-day. [Illustration: THE NORTHERN END OF THE GULF OF SUEZ.]