Early progress in any art or science is commonly intermittent. It was so in the story of aeronautics. Advance was like that of the incoming tide, throwing an occasional wave far in front of its rising flood. It was a phenomenal wave that bore Roger Bacon and left his mark on the sand where none other approached for centuries. In those centuries men were either too priest-ridden to lend an ear to Science, or, like children, followed only the Will-o'-the-Wisp floating above the quagmire which held them fast. They ran after the stone that was to turn all to gold, or the elixir that should conquer death, or the signs in the heavens that should foretell their destinies; and the taint of this may be traced even when the dark period that followed was clearing away. Four hundred years after Roger's death, his illustrious namesake, Francis Bacon, was formulating his Inductive Philosophy, and with complete cock-sureness was teaching mankind all about everything. Let us look at some of his utterances which may help to throw light on the way he regarded the problem we are dealing with. "It is reported," Francis Bacon writes, "that the Leucacians in ancient time did use to precipitate a man from a high cliffe into the sea; tying about him, with strings, at some distance, many great fowles; and fixing unto his body divers feathers, spread, to breake the fall. Certainly many birds of good wing (as Kites and the like) would beare up a good weight as they flie. And spreading of feathers, thin and close, and in great breadth, will likewise beare up a great weight, being even laid without tilting upon the sides. The further extension of this experiment of flying may be thought upon." To say the least, this is hardly mechanical. But let us next follow the philosopher into the domain of Physics. Referring to a strange assertion, that "salt water will dissolve salt put into it in less time than fresh water will dissolve it," he is at once ready with an explanation to fit the case. "The salt," he says, "in the precedent water doth by similitude of substance draw the salt new put in unto it." Again, in his finding, well water is warmer in winter than summer, and "the cause is the subterranean heat which shut close in (as in winter) is the more, but if it perspire (as it doth in summer) it is the less." This was Bacon the Lord. What a falling off--from the experimentalist's point of view--from Bacon the Friar! We can fancy him watching a falcon poised motionless in the sky, and reflecting on that problem which to this day fairly puzzles our ablest scientists, settling the matter in a sentence: "The cause is that feathers doe possess upward attractions." During four hundred years preceding Lord Verulam philosophers would have flown by aid of a broomstick. Bacon himself would have merely parried the problem with a platitude!