Wilkins was a famous man in his day; he married a sister of Oliver Cromwell, and in his later years was Bishop of Chester. But his great work was the founding of the Royal Society; and his philosophical (or, as they would now be called, scientific) writings, which belong to his earlier years in London, show very clearly with what high expectations the society started on its labours. The first of these writings, published in 1638, is a discourse to prove that there may be another habitable World in the Moon. The second considers the possibility of a passage thither. The third maintains that it is probable that our Earth is one of the planets. The fourth, which is entitled _Mercury; or, the Secret Messenger_, discusses how thoughts may be communicated from a distance. The fifth and last, published in 1648, is called _Mathematical Magic_, and is divided into two books, under the titles _Archimedes; or, Mechanical Powers_, and _Daedalus; or, Mechanical Motions_. In this latter book Wilkins treats of mills, clocks, and the contrivance of motion by rarefied air; of the construction of an ark for submarine navigation, and of its uses in war; of a sailing chariot, to be driven on the land as ships are on the sea; of the possibility of perpetual motion; and, in chapters vii and viii, of the art of flying. There are four ways, according to Wilkins, whereby flying in the air may be attempted. The first is by spirits or angels; but this branch of the subject does not belong to natural philosophy. The next is by the help of fowls, which the learned Francis Bacon thought deserving of further experiment. Two ways remain of flying by our own strength; we may use wings fastened immediately to the body, or we may devise a flying chariot. If we are to use wings, he says, we must be brought up in the constant practice of them from youth, first 'running on the ground, as an ostrich or tame goose will do ... and so by degrees learn to rise higher.... I have heard it from credible testimony, that one of our own nation hath proceeded so far in this experiment, that he was able by the help of wings, in such a running pace, to step constantly ten yards at a time.' The arms of a man extended are weak, and easily wearied, so he thinks it would be worth the inquiry whether the wings might not be worked by the legs being thrust out and drawn in again one after the other, so as each leg should move both wings. But the best way of flying would be by a flying chariot, big enough to carry several persons, who might take turns to work it. Wilkins is quite honest in recognizing the difficulties of this scheme. He deals fully with the chief of them--whether so large and heavy a machine can be supported by so thin and light a body as the air; and whether the strength of the persons in it can be sufficient for the motion of it. In his attempt to show that these objections are not insuperable, he makes some true remarks. He had