AN ACCOUNT OF THE TRIGONOMETRICAL SURVEY, CARRIED ON BY ORDER OF THE MASTER-GENERAL OF HIS MAJESTY'S ORDNANCE, IN THE YEARS 1800, 1801, 1803, 1804, 1805, 1806, 1807, 1808, AND 1809. BY LIEUTENANT-COLONEL WILLIAM MUDGE, OF THE ROYAL ARTILLERY, F. R. S. AND CAPTAIN THOMAS COLBY, OF THE ROYAL ENGINEERS. VOL. III. LONDON: PRINTED BY W. BULMER AND CO. CLEVELAND-ROW, ST. JAMES'S; AND SOLD BY W. FADEN, GEOGRAPHER TO HIS MAJESTY, CHARING-CROSS. PREFACE. In the year 1800 a paper was presented to the public, through IN the medium of the Philosophical Transactions, giving an account of the Trigonometrical operations performed in 1797, 1798, and 1799. Before we enter on the particulars composing the body of the following work, it will be proper to take a short view of the state of this undertaking at different periods since the commencement of it, in the year 1791, to the state of it in the year 1799. The first communication on the subject of this Survey was made to the Royal Society, and printed in their volume for 1795. In that account is given a detail of the whole of the opera tions previously performed for effectuating the initial parts of the Survey. These principally consisted of the measurements of the base lines on Hounslow Heath and Romney Marsh, joining the triangles proceeding from the former, to those of the late Major General Roy, at Fairlight Down, and intermediately at other stations, and measuring a base of verification on Salisbury Plain. The second paper is found in the Philosophical Transactions for the year 1797. This contains the triangles carried on in the two previous years, from the base line on Salisbury Plain, |