The seventeenth century had still preferred to investigate the far off heavens and to study the position of our planet in relation to the solar system. Even so, the Church had disapproved of this unseemly curiosity, and Copernicus who first of all had proved that the sun was the centre of the universe, did not publish his work until the day of his death. Galileo spent the greater part of his life under the supervision of the clerical authorities, but he continued to use his telescope and provided Isaac Newton with a mass of practical observations, which greatly helped the English mathematician when he dis-covered the existence of that interesting habit of falling objects which came to be known as the Law of Gravitation.