meeting one another at Tennis, and Billiards: Dr. Wren produc'd before the Society, an Instrument to represent the effects of all sorts of Impulses, made between two hard globous Bodies, either of equal, or of different bigness, and swiftness, following or meeting each other, or the one moving, the other at rest. From these varieties arose many unexpected effects; of all which he demonstrated the true Theories, after they had been confirm'd by many hundreds of Experiments in that Instrument. These he propos'd as the Principles of all Demonstrations in Natural Philosophy: Nor can it seem strange, that these Elements should be of such Universal use; if we consider that Generation, Corruption, Alteration, and all the Vicissitudes of Nature, are nothing else but the effects arising from the meeting of little Bodies, of differing Figures, Magnitudes, and Velocities.
The Second Work which he has advanc'd, is the History of Seasons: which will be of admirable benefit to Mankind, if it shall be constantly pursued, and deriv'd down to Posterity. His proposal therefore was, to comprehend a Diary of Wind, Weather, and other conditions of the Air, as to Heat, Cold, and Weight; and also a General Description of the Year, whether contagious or healthful to Men or Beasts; with an Account of Epidemical Diseases, of Blasts, Mill-dews, and other accidents, belonging to Grain, Cattle, Fish, Fowl, and Insects. And because the difficulty of a constant Observation of the Air, by Night and Day, seem'd invincible, he therefore devis'd a Clock to be annex'd to a Weather-Cock, which mov'd a Rundle, cover'd with Paper, upon which the Clock mov'd a black-lead-Pencil; so that the Observer by the Traces of the Pencil on
