In 1784 English natural philosopher and geologist John Michell published in the Philosophical Transactions of the Royal Society Vol. 74, Pt. 1 "On the Means of discovering the Distance, Magnitude &c. of the Fixed Stars, in consequence of the Diminution of the Velocity of their Light, in case such a Diminution should be found to take place in any of them, and such other Data should be procured from Observations, as would be farther necessary for that Purpose."
"This paper was only generally 'rediscovered' in the 1970s and is now recognised as anticipating several astronomical ideas that had been considered to be 20th century innovations. Michell is now credited with being the first to study the case of a heavenly object massive enough to prevent light from escaping (the concept of escape velocity was well known at the time). Such an object would not be directly visible, but could be identified by the motions of a companion star if it was part of a binary system. Michell also suggested using a prism to measure the gravitational weakening of starlight due to the surface gravity of the source ('gravitational shift'). Michell acknowledged that some of these ideas were not technically practical at the time, but wrote that he hoped they would be useful to future generations. By the time that Michell's paper was 'resurrected' nearly two centuries later, these ideas had been reinvented by others" (Wikipedia article on John Michell, accessed 02-28-2009).