Dissertations and letters, by Don Joseph Rodriguez, the Chevalier Delambre, Baron de Zach, Dr. Thomas Thomson, Dr. Olinthus Gregory, and others : tending either to impugn or to defend the trigonometrical survey of England and Wales ; carrying on by Col. Mudge and Capt. Colby. Collected, with notes and observations, including an exposure of the misrepresentations and contradictions of Dr. Thomson, and a defence of the late Astronomer Royal against the imputations of Baron de Zach. /by Olinthus Gregory, LL. D. of the Royal Military Academy.