"The typhoon blows in a circle, and may be briefly described as a rapidly revolving wind that has a diameter of from two to five hundred miles. It is a whirlwind on a large scale, and as furious as it is large. A curious fact about it is that it has a calm centre, where there is absolutely no wind at all, and this centre is sometimes forty or fifty miles across. Nearest the centre the wind has the greatest violence, and the farther you can get from it, the less severe is the gale. Mariners always try to sail away from the centre of a typhoon, and I have known a ship to turn at right angles from her course in order to get as far as possible from the centre of a coming tempest. There is a great difference of opinion among captains concerning these storms, some declaring that they have been in the middle point of a typhoon and escaped safely, while others aver that no ship that was ever built can withstand the fury of a storm centre. But I think the weight of evidence is in favor of the former rather than the latter, as I have known captains who have described their situation in such a way as to leave not the slightest doubt in my mind of the correctness of their statements. "If you have any desire to study the subject fully, I advise you to get 'Piddington's Law of Storms;' you will find it treated very fully and intelligently, both from the scientific and the popular point of view. [Illustration: A TYPHOON.] "It has never been my fortune," the Doctor continued, "to be farther in a typhoon at sea than the outer edge, but that was quite as much as I wanted. One time on land I saw and felt one of these tempests; it drove ships from their moorings, swamped hundreds of boats, unroofed many houses, tore trees up by the roots, stripped others of their branches, threw down walls and fences, flooded the land, and caused a vast amount of havoc everywhere. Hundreds of people were drowned by the floods, and the traces of the storm will last for many years. The city that has suffered most by these storms is Calcutta. On two occasions the centre of a typhoon has passed over the harbor or within a few miles of it, and the whole shipping of the port was driven from its moorings and the greater part completely or partially wrecked." While they were listening to the remarks of the Doctor the boys observed that the wind was increasing, and as they looked at the compass they found that the ship's course had been changed. Everything about the vessel that could be made fast was carefully secured, and the party was notified that they might be ordered below at any moment. The waves were not running high, and but for the very severe wind there would have been nothing to cause more than ordinary motion on board the steamer.