The Life of Dr. Robert Hooke.

May 23rd, 1666. There was read a paper of Mr. Hooke’s explaining the inflection of a direct motion into a curve, by a supervening, attractive principle, which was ordered to be registered. The discourse contained therein is an introduction to an experiment to show that circular motion is compounded of an endeavor by a direct motion by the tangent, and of another endeavor tending to the center. To this purpose, there was a pendulum fastened to the roof of the room with a large wooden ball of Lignum Vitae original: "Lignum Vitae"; a hard, dense tropical wood. on the end of it. It was found that if the impetus of the endeavor by the tangent, at the first setting out, was stronger than the endeavor to the center, there was generated an elliptical motion whose longest diameter was parallel to the direct endeavor of the body at the first impulse. But if that impetus were weaker than the endeavor to the center, there was generated an elliptical motion whose shorter diameter was parallel to the direct endeavor of the body in the first point of the impulse; if both were equal, a perfect circular motion was made. There was also another experiment performed by fastening another pendulous body by a short string on the lower part of the wire by which the greater weight was suspended, that it might freely make a circular or elliptical motion around the bigger, while the bigger moved circularly or elliptically about the first center. The intention of this was to explain the manner of the moon's motion about the earth. It appeared evidently that neither the bigger ball, which represented the earth, nor the less, which represented the moon, were moved in as perfect a circle or ellipse as they would have been if either of them had been suspended and moved singly; but that a certain point which seemed to be the center of gravity of the two bodies (however positioned and considered as one) seemed to be moved regularly in such a circle or ellipse, the two balls having other peculiar motions in small epicycles A small circle whose center moves around the circumference of a larger circle. about the said point.

August 1st, 1666. He read his observations of the comet in 1664, later printed among his tracts and called Cometa. The same person produced a certain contrivance to show that the circular pendulum was made of two straight lines crossing each other, etc., and about the same time, his instrument to take the distance of the stars from the moon, with one object seen directly and the other by reflection. This is published in his book, page 503.

The dreadful conflagration of a great part of the city of London The Great Fire of London, 1666. happening in the beginning of September 1666 brought another great hindrance to the Society's proceedings; they were obliged to remove their usual place of meeting from Gresham College to Arundel House in the Strand, where, by the favor of the then Duke of Norfolk, they prosecuted their former inquiries. Their first meeting at Arundel House was on January 9, 1666/7.

On September 19, 1666, he produced a model he had designed for the rebuilding of the city, with which the Society was very well pleased. Sir John Laurence, the then late Lord Mayor, addressed himself to the Society, expressing the present Lord Mayor and Aldermen’s liking of it, as also their desire that it might be shown to his Majesty, as they preferred it far before the model drawn up by the city surveyor.