CHAPTER XII
INVASION OF THE SEA
THE POSSIBILITY that the wind was the first inanimate power utilized by man, has already been referred to. There are records of the use of sailing vessels in Egypt that date as far back as 6,000 years before Christ. Navigators of that early date, however, could hardly claim to have mastered the wind. They merely used wind power when the wind was disposed to help them. If the winds were adverse, they had no recourse other than to furl their sail, step the mast and depend upon oars to propel them to the desired port. It was not until thousands of years later that primitive mariners learned how to tack and pursue a zigzag course against the wind. When this knowledge was acquired we do not know, but it is certain that the Phœnicians, who rounded the continent of Africa 1,200 years before Christ, knew how to make use of the power of opposing winds. Of course they could not explain how it was that a breeze could be made to drive a vessel in a direction across and even opposed to that in which it was blowing. In order to understand this apparent paradox ourselves, we must go back to the very elements of mechanics.