Here and there in this region as elsewhere in the ocean he saw a little cluster of notations representing the weather reports furnished by radio from some vessel. Over one of these he paused. The ship, three hundred miles southeast of Yokohama, had reported a barometric pressure of 1011, but by its position on the map it should have reported about 1012. A difference of one millibar, he realized, was inconsiderable and might easily result from an inaccurate barometer or from a careless reading of the instrument. For these reasons he had at first permitted himself to neglect this particular report. But now he reconsidered.

The ship’s position was about half way between the island weather-stations of Hatidyosima to the north and Titijima to the south, about two hundred miles distant from each. But the temperature of the air at the ship was only two degrees warmer than at Hatidyosima, whereas it was twelve degrees colder than at Titijima. This was clear indication that the ship had already been engulfed in the cooler air which was sweeping out with the monsoon, and that somewhere between the ship and the southern island the cooler air which had come from the north would be pushing against the warmer southern air. He himself had already recognized this fact by drawing a blue line, indicative of a “cold front,” from the center of Antonia westward and southward clear to the Chinese coast. Along such a boundary between cool and warm air a new storm was almost certain to form somewhere.

No other ships reported from that vicinity. Glancing at the wind-arrows of the two island stations, he saw that they tended to contradict rather than confirm the reading of the ship’s barometer. Hatidyosima had a northeast wind instead of northwest; Titijima a west wind instead of south or southwest. Practically, he realized, the whole matter was of no importance, but he felt the twinge of scientific curiosity and the challenge of a difficult problem.

Methodically he checked back over the maps of the last ten days, and determined that there had never before been an occasion to doubt the accuracy of the reports from this particular ship. He paused a moment with eraser held above the blue line. The ship’s barometer-reading, he considered, along with the general probability of the whole situation indicated an incipient storm. The failure of the island reports to confirm would mean only that the disturbance was as yet too small to have affected them. This in itself lent a piquancy, for seldom was it possible to spot a storm so close to its beginning.