Abstract

This paper sets out to examine the changes which took place in Thomas Young's concepts of the ether between 1799 and 1807. During the earlier part of this period he supposed the ether to consist of mutually repelling subtle particles which are attracted to particles of matter. Hence, he considered that the ether is denser within dense bodies than in rare ones. Furthermore, Young proposed that the ether density does not change abruptly at an interface; instead the denser ether extends beyond the geometrical limit of a body to form an atmosphere around it. As this hypothesis of an atmosphere of dense ether surrounding material bodies will be the central subject of this paper, I shall in future refer to it as the ether distribution hypothesis.