"The subject first in order seems to be the Red Sea; and we have not yet spoken of it in detail, though we have had considerable to say about it. I shall purposely omit some things which will be explained when we come to them. I am glad to see that you have brought your diaries or note-books with you, as I suggested, and you can write down the names of notable sights and the figures I shall give. I wish to say that I have always prepared myself for these occasions, and do not talk to you at random.
"The Red Sea is an arm of the Indian Ocean, with the Gulf of Aden, about 800 miles long, as a connection between them. The Persian Gulf, with the Gulf of Oman, forms a similar body of water, and they will probably render the same service to England and India that the Red Sea does at the present time. Arabia lies between them. The sea on which we are now sailing is 1,200 miles long."
"Badaeker gives the length as 1,400 miles," said Louis.
"He gives it in English miles," replied the commander. "A degree of a great circle is 69.07 English, or statute miles as we call them, or 60 geographical sea miles or knots. This distinction has been fully explained to you before. For ordinary purposes the number of sea miles is to the number of statute miles in the ratio of six to seven. In other words, there will be six-sevenths as many knots as statute miles, and conversely, seven-sixths as many statute as sea miles. Six-sevenths of 1,400 is 1,200; and thus we agree.
"The Red Sea varies in width from 100 to 200 miles, and in the broadest part it is 205 sea miles. We are still in the Gulf of Suez, and shall be till about five this afternoon. On the African side you will see mountains all the way to the strait, with only sand between them and the water. There is nothing that can be called a town between Suez and Koser, over 300 statute miles. All around the sea are coral-reefs; and we shall pass a lighthouse on one right in the middle of it. Not a single river flows into the Red Sea, for there are no rains in Egypt; and if there were on either side, the desert would absorb all the water.
"This sea has the reputation of being a hot region. The thermometer ranges from 70° to 94°, and sometimes the mercury mounts to over 100°, always in the daytime, and it may fall to the freezing point at night, though rarely. As on the Nile, the rule is hot days and cool nights, though you may find some of the latter uncomfortable farther south, for the water has shown a temperature of 100°.
"The water is somewhat salter than the ocean, because no rivers empty into it, and because of excessive evaporation. It has been said by some scientists that, if the Red Sea were entirely enclosed, it would become a solid body of salt in less than two thousand years. I suppose they mean that all the fluid would evaporate, and the salt in it would remain at the bottom. We will not worry about it.
"The average depth of this sea is 2,250 feet, and the greatest 7,200. I have nothing more to say about it; but while I am up I will say a few words about the new route to India of which I have spoken before. The Gulf of Iskanderun, sometimes called Scanderoon, is the north-east corner of the Mediterranean. Its eastern shore is within a hundred miles of the headwaters of the Euphrates River, which is navigable for small craft to Bir. Sixty years ago some preferred it to the Suez route. A grant of money was made by Parliament, two iron steamers of small size were put into the river; and though one of them was sunk, the other went through to the Persian Gulf.
"It was shown that this route was about a thousand miles less in distance than any other to Kurrachee, the nearest port in India. But political influences were at work against it, first from Egypt, and then from some of the Powers, in the belief that it would give England an advantage in the affairs of Asia, and the scheme was dropped. Now we will take a walk of half an hour about the ship; for school-children need rest and recreation.
"But I wish to remind you again that you are now near the ancient world; for Arabia is in sight all the time, and Assyria, Babylonia, Syria are beyond it. The professor will have the floor after the intermission."