"It means that the trade wind, which keeps this island cool even in the hottest summer, has been dying down, since yesterday. Now, since the trade winds blow constantly, and are a part of the unchanging movements of the atmosphere, you can see for yourself that any disturbance of the atmosphere which is violent enough to overcome the constant current of the trade winds must be of vast size and of tremendous force. "What can such a disturbance be? The only answer is--a hurricane. "Then there's another reason for feeling heat. That would be if the air were unusually hazy and moist. Now, if you'll observe, during this morning and the early part of the afternoon, the air has been clear, then hazy, then clear again, and is once more hazy. That shows a rapid and violent change in the upper air. "So far, so good. Now, in addition to observations of the clouds, the sea and the air at the surface, it helps--more, it is all-important--to check these observations by some scientific instrument which cannot lie. For this, we must use the barometer, which, as you probably know, is merely an instrument for weighing the air. When the air is heavier the barometer rises, when the air grows lighter, the barometer falls. "Yesterday, the barometer rose very high, much higher than it would in ordinary weather. This morning, it was jumpy, showing--as the changes in the haziness of the air showed--irregular and violent movements in the upper atmosphere. It is now beginning to go down steadily, a little faster every hour. This is an almost sure sign that there is a hurricane in action somewhere, and, probably, within a few hundred miles of here. "But tell me, Stuart, since we have been talking, have you noticed any change in the atmosphere, or in the sky." "Well," answered the boy, hesitating, for he did not wish to seem alarmist, "it did seem to me as if there were a sort of reddish color in the sky, as if the blue were turning rusty." "Watch it!" said the botanist, with a note of awe in his voice, "and you will see what you never have seen before!" For a few moments he kept silence. The rusty color gradually rose in intensity to a ruby hue and then to an angry crimson, deepening as the sun sank. Over the sky, covered with a milky veil, which reflected this glowing color, there began to rise, in the south-west, an arch of shredded cirrus cloud, its denser surface having greater reflecting powers, seeming to give it a sharp outline against the veiled sky. The scientist rose, consulted the barometer, and returned, looking very grave. "It looks bad," he said. "There is not much doubt that it will strike the island." "Take to the hurricane wing, then!" suggested Stuart, a little jestingly. In common with many Barbados houses, the botanist's dwelling was provided with a hurricane wing, a structure of heavy masonry, with only one or two narrow slits to let in air, and with a roof like a gun casemate.