ABSTRACT
In order to complete the story of the progress of astronomy in the age of Newton it is necessary to give an account of his chief contemporaries and of the work done at the Paris and Greenwich Observatories, with one or other of which most of them was associated in some way. The fundamental operation in all precise astronomy is that of accurately measuring the angle subtended at the observer’s eye by two given points on the celestial sphere. Hence the fundamental instrument of precise astronomy has always consisted essentially of a circle or arc graduated in angle, and traversed by a radial index carrying sights and pivoted at the centre of the circle. The superiority of Romer’s method of observing lay in the avoidance of cumbrous instruments for measuring celestial angles.
