"Now, as I said," the Doctor resumed, "no great steamer is ever likely to be delayed for a month or anything like a month, at sea. In the first place, each of them carries a skilled chief engineer and a corps of competent assistant engineers, a force of blacksmiths and machinists, and better still, duplicates of all those parts of her engines that are liable to break down. I remember one voyage on the American liner Berlin, when in midocean one of our cylinders cracked and threatened to burst under the steam pressure. The captain stopped the ship and the engineers and machinists cut that cylinder out. We lay there for twenty hours in a surging sea, and then proceeded, running with only two of our three cylinders in use."

"But what an awful bobbing about you must have got," said Ed, "lying out there on the sea, with no headway."

"Oh, no!" answered the Doctor. "Our bow was kept always toward the oncoming waves, so that we rode rather more easily than if we had been running under steam, for if we had been running we should have laid our course straight for New York, taking the waves from any direction. As it was, we got them dead ahead."

"But how did they hold the bow always toward the coming waves?" asked Ed.

"By the use of what they call 'sea anchors.' These are great hollow cones, made of iron. At the big end of each a cable is fastened, and the anchors are thrown overboard, usually three or four of them. Of course, it is impossible in deep seas to send an anchor down to the bottom, but these big cones catch the water, and by their dragging in it, they hold the ship pretty nearly stationary, and, more important still, they keep her head always pointed toward the wind and waves, so that she rides easily. Whenever a ship breaks down at sea she hoists three great black disks into her rigging. These mean to any ship that may approach, that the steamer is 'not under control'—that is to say, that as she is not running, she has no power to steer to one side or the other or in any other way to keep out of the path of the approaching vessel. Then, the approaching vessel steers clear of the disabled steamer, and usually she hoists a set of signal flags, asking if the steamer needs or wants any assistance, and the steamer replies with another set of flags giving her response to the offer. The flag signalling system has been so completely perfected by international agreement that two captains can carry on any conversation they please by means of it, even though neither can speak a word of the other's language.

"Now this is the other reason why no steamer is ever likely to lie crippled on the ocean for a month or any thing like it. There are regular pathways on the ocean over which all the regular line steamers pass. So, while the ocean is so immense that you may steam over it for days without seeing a vessel of any kind, nevertheless no steamer is likely to lie disabled for more than a few days without sighting some other that stands ready to render assistance. If the disabled steamer needs anything the other furnishes it. If she is too far broken down in her machinery to repair it at sea, the other will generally take her in tow. If she is likely to sink—the most unlikely of all things—the other will take off her crew and passengers and leave the ship to her fate."

"Why do you say, Doctor, that sinking is the most unlikely of all things?" asked Jack. "I should think it the most likely."

"Not at all," the Doctor replied. "The modern steamship is perhaps the most perfect product we have of scientific precision in construction. As well as you know that twice two makes four, the builders of a modern steamship know to the uttermost pound the amount of strain that any wave blow can put upon any part of the ship, and they provide for it four times over. Except in case of collision in a fog, the great ocean liner simply cannot sink at sea. If you took her out to mid ocean and there abandoned her, she would float securely until some current should drive her on rocks or some other sort of shore. At sea, she is absolutely unsinkable, except as I say by collision, and that is as true when she is carrying thousands of tons of freight as at any other time."

"It is very wonderful," said Jack.

"Of course it is. If I were called upon to name the modern seven wonders of the world, I should unhesitatingly put the ocean greyhound first in the list. But come boys! It is past our bed time, and we've heavy work to do to-morrow in getting those three great timbers ready to send down the chute."