"We will have it in less than two hours," said the scientist. "It is a good thing that all afternoon I have had the men and women on the place nailing the shutters tight and fastening everything that can be fastened. We may only get the edge of the hurricane, we may get the center. There is no telling. An island is not like a ship, which can direct its course so as to escape the terrible vortex of the center. We've got to stay and take it."
"But has every hurricane a center?" queried the boy, a little relieved by the thought that the storm would not come for two hours. In that time, he foolishly thought, it might have spent its force. He did not know that hurricanes possess a life of their own which endures not less than a week, and in one or two cases, as long as a month.
"You wouldn't ask whether every hurricane has a center," the scientist replied, "if you knew a little more about them. As there is nothing for us to do but wait, and as it is foolish to go to the hurricane wing until the time of danger, I might as well explain to you what a hurricane really is. Then, if you live through it——" Stuart jumped at the sudden idea of the imminent danger—"you'll be able to write to your paper about it, intelligently."
"I'd really like to know," declared Stuart, leaning forward eagerly.
"Well," said his informant, "I'll make it as simple as I can, though, I warn you, a hurricane isn't a subject that can be explained in a sentence or two.
"You know that summer and winter weather are different. You ought to be able to see that summer and winter winds are different. The difference in seasons is caused by the respective positions of the northern and southern hemispheres to the sun. The greater the heat, the greater the atmospheric changes. Hurricanes are great whirls caused by violent changes of the air. Therefore hurricanes come only in the summer."
"That's clear and easy!" declared the boy, delighted that he was able to follow the explanation.
"Now, as to why hurricanes strike here and nowhere else. I'll try and explain that, too. There is a belt of ocean, just north of and on the equator, known as the 'doldrums,' where it is nearly always calm, and very hot. There is also a belt of air running from Southern Europe to the West Indies where the north-east trade winds blow all the year round. Between this perpetual calm of the doldrums and the perpetual wind of the trades is a region of atmospheric instability.
"Now, consider conditions to the west of us. The Caribbean Sea and the Gulf of Mexico, together, form what is almost a great inland sea with the West Indian Islands as its eastern shore. The trade winds do not reach it. The Pacific winds do not reach it, for they are diverted by the high ranges of Central America. The winds from North America do not reach it, because these always turn northwards on reaching the Mississippi Valley and leave the United States by the St. Lawrence Valley.
"So, Stuart, you can see that the Caribbean Sea and the Gulf of Mexico have over them, in summer, a region of air, little disturbed by wind, not far from the Equator and which, therefore, becomes steadily heated and steadily saturated by the evaporation from the body of water below."