Extract of a letter from the Rev. John Brinkley, D. D. F. R. S. Andrew’s Professor of Astronomy in the University of Dublin, to the Rev. Nevil Maskelyne, D. D. F. R. S. Astronomer Royal, on the annual parallax of α lyræ

The principal object of Dr. Maskelyne in making this communication, is to inform the Society of a discovery, made by Dr. Brinkley, of the parallax of the annual orbit, which he has ascertained by observations on α Lyræ. So that by the Result of 47 observations, the result is 2"·52; and Dr. Brinkley adds, that from the confidence which he has now acquired in his instrument, he has no doubt that the annual parallax exceeds 2".