"Well," the Forecaster replied, "fourteen miles an hour is a good enough breeze for kite-flying. How about it, boys? Shall we try a flight to-day?" "Oh, let's!" the boys exclaimed. "Very well," said the Forecaster, "we'll put the kites together. Have any of you ever seen a weather kite?" he queried. "I've seen a picture of one, sir," said Fred. "I saw it in one of the Weather Bureau booklets. It looked like a box with the ends knocked out. Are these like that?" "Yes," the weather expert replied, "all over the world the Hargrave or box kite is used. There's a little difference in the methods of bracing the frames, but the principle of them all is the same." "Are they the best kites for lifting, sir?" asked Anton. "I saw a picture, once, of a man being carried along the ground by a kite, but it didn't look like this. It was like a lot of little triangles all piled one on top of the other." "That's a different kind," the Forecaster answered, "it's called a tetrahedral kite, and was invented by Dr. Alexander Graham Bell. They will lift a man quite easily. Owing to the form of construction, they're much heavier and harder to handle and they won't go up as high. The box kites fly higher and more easily. They'll go up even in the lightest wind, and that's quite important, boys, because you must remember that sometimes there's quite a strong wind in the upper layers of the air when there's only a zephyr below. As you see, boys, this kite consists simply of four long sticks arranged in a square, with one third of the length at either end covered with a specially treated and tightly stretched muslin." He was working rapidly as he talked, and, before long the kite was assembled, the wire attached and wound on the reel and all was ready for launching. "Will that wire hold it, sir?" asked Ross, as he noted the extremely fine line that the Forecaster was using. "Certainly, it's piano wire. It's only a thirty-second part of an inch in diameter, but it will stand a pull of nearly three hundred pounds. That's more than you could pull. More even than Monroe could pull, and he's the strongest of you." "Couldn't I hold one of those small kites, sir?" asked Monroe. "Yes," the Forecaster said, "you could with a well-made hand reel, and if the wind wasn't too strong. But your arms would soon give out. Of course, the pull of a kite depends on the amount of square feet of sail area. Anton," he added, turning to the crippled lad, "you're the mathematician of the League, measure that kite and tell us how many square feet of sail area it has." Anton took a foot rule from his pocket and measured the kite rapidly. "A trifle over thirty-six feet, sir," he said. "I can give you the fractions, if you like."