"What is known as emery is the more or less impure product from the same source. I think I have stated heretofore that both of these products come from the precious gems; the blue variety is known under the name of sapphire; the red as ruby; the yellow as oriental topaz, and the violet as oriental amethyst."
During that and the following day the Professor spent some time in prospecting for the gems, but if he succeeded in finding any samples he did not make the discovery known.
A few days after this Harry announced that he was ready to lay the keel of the new boat. All the material had been prepared, and was at the beach. Prior to this the island had been visited by a heavy storm. They had been frequent within the past month, but this was not considered unusual.
The Professor insisted that a temporary shed should be erected to cover the material, as moisture would make it very undesirable for the vessel, and a day was occupied in putting up the structure.
An entire week thus passed, every hour of which was devoted with the utmost diligence to the various enterprises. The keel was laid and the work of putting on the bottom boards was progressing rapidly. One night, a few days after the laying of the keel, a brisk wind sprang up, which continued during the night, increasing in fury, and in the morning evidences were seen on all sides of the effect of the tempest.
"It seems very singular," was George's observation, "that we should have such terrible winds here."
The Professor had evidently expected the storms. "Do you remember the experience we had less than a year ago? We had five days of this on the ocean."
"I had forgotten that. Do they occur every year?"
"You may have heard of the monsoons, a periodical wind in the Indian Ocean, which is a northeast wind, and they blow with greater or less force from November to March."
"What causes them to blow with such regularity during those periods?"