"It was not intended to be straight," answered the commander. "I am following the course laid down by Captain Scott for the Maud, so that I shall be able to find him to-morrow morning. I should have gone farther to the north of Alboran, and I should not have seen it in consequence; but I thought he might need the light to assure him where he was." "Here is another little red cross just north of Algiers, with a red line drawn from it to the one north of Alboran," said Dr. Hawkes, scrutinizing the chart very closely. "That, I conclude, is the course between the two crosses." "Quite right, Doctor; you would easily become a navigator." "I shall not make the struggle. But why is the point north of Algiers chosen rather than some other one?" "I took Captain Scott's mark, which he selected, ten miles north of Algiers, because the course to it would carry him clear of the coast of Africa, and of all dangers of every kind from rocks or shoals. When we get to Captain Scott's point off Algiers, we shall make the course a quarter of a point more to the north, so as to pass Ras al Koran, where the navigation becomes more difficult on account of rocks and shoals." "But how in the world do you know which way to steer in order to reach Captain Scott's red cross at the end of the red line?" inquired Mrs. Belgrave, who had been studying the chart with all her might, though it was about the same as trying to read the notice posted on a Chinaman's laundry. "And what are all these rings on the chart for?" asked Mrs. Blossom, as she put her finger on one of the diagrams of the compass. "You both ask about the same question," replied the commander, as he picked up his parallel rule, and began to work the same problem before described. "This is called a parallel rule," he added, working it back and forth. "The brass connecting pieces keep the two parts of the implement exactly parallel." "What is the use of keeping the pieces parallel?" "That is what I am going to show you." He placed the rule so that one edge was on both of the red crosses. He then worked the rule to the nearest diagram, and took off the course east a quarter south. But the ladies would not be satisfied till they had done it for themselves, and the captain made other crosses till they could do it very well. CHAPTER XXVIII MORRIS ON "THE RULE OF THE ROAD" On board of the Maud it had been issued as an order by Captain Scott after the matter had been fully talked over, that the watches should be four hours in length, except the dog-watches, which were to be half as long, both in the sailing and the engineer department. The arrangement was precisely the same as on board of the Guardian-Mother, or any other ship at sea. The tricks at the wheel were to be two hours in length.