After a time the waves broke into what is called a "choppy sea;" the wind was so great that their crests were blown away before they could rise to any height worthy of notice. Mariners say that in a severe typhoon the ocean is quite smooth, owing to the inability of the waves to form against the irresistible force of the wind. It is fortunate for them that such is the case, as they could not possibly survive the combined action of the cyclone and the great waves together.
For three or four hours the wind continued to increase, and the waters to assume the shapes we have seen. The barometer had fallen steadily, and everything indicated that the arrival of the steamer at Shanghai, or at any other port, was by no means a matter of certainty. The order was issued for the passengers to go below, and our friends descended to the cabin. Just as they did so the decks were swept by a mass of water that seemed to have been lifted bodily from the sea by a gust of wind. The order to go below was not issued a moment too soon.
The Doctor took another glance at the barometer, and discovered something. The mercury was stationary!
Ten minutes later it had risen a few hundredths of a degree. The rise was small, but it was a rise. In another ten minutes another gain was perceptible.
The Doctor's face brightened, and he called the boys to observe what he had discovered. He had already explained to them that the barometer falls at the approach of stormy weather, and rises when the storm is about to pass away. Before a storm like a typhoon the fall is very rapid, and so certainly is this the case that mariners rely upon the barometer to give them warning of impending danger.
An hour from the time they went below they were allowed to go on deck again. The wind had abated a little, so that there was no further danger of their being swept from the decks by the water; the clouds were less dense and the rain was not falling so heavily. In another hour there was another perceptible decline in the wind, and a little later the ship was again put on her course. The captain announced the danger over, and said the centre of the typhoon had passed at least a hundred miles to the west of them. "If we had kept our course," said he, "we should have been much nearer to it, and then the storm would have been more dangerous for us."
"How do you know which way to turn?" Frank asked; "it seems to me you are just as likely to run to the centre of the storm as to the circumference."
"There's where you don't understand the science of storms," said the captain smiling. "In the northern hemisphere typhoons, cyclones, and hurricanes—they are all the same—whirl from left to right, that is, they turn like the hands of a watch, while in the southern hemisphere their motion is exactly the reverse. When we think we are in the sweep of a typhoon in these waters, we run with the wind on our starboard, or right hand, and that course will take us away from the centre. In the southern hemisphere we run with the wind on the port, or left hand, with the same result. But we'll go to dinner now and be happy, for the danger is over."
