An Account of the Operations Carried on for Accomplishing a Trigonometrical Survey of England and Wales: From the Commencement, in the Year 1784, to the End of the Year 1796, Volume 2
W. Bulmer and Company, 1801
Agnes Beacon Amplitude of arc Angles corrected Arbury Hill arch Ash Beacon axis azimuth Bardon Hill Beacon Hill Black Bodmin Bow Brickhill Bradley Knoll Brill Broadway Beacon Bull Barrow Butterton Cadon Barrow Carraton Hill Clifton Corley Cygni degree depr distance at Dunnose Ditto Dover Court Draconis Dundon Beacon Dundry Epwell feet Flagstaff Gravesend Gringley Hadleigh Halstow Hatfield Broad Oak Heath Heathersedge Hensbarrow Herculis Highbeech Highclere Kinsworth Langdon Hill Lansdown Lavenham length Lidlington Lillyhoe Line of collimation Lugshorn Corner Mean Mendip Hills Moor Lynch Names of stations Nuffield Obelisk Observatory Observed angles Observed Zenith Distance Orpit Peldon perpendicular Pilsden Plate plumb-line Point Quainton Rayleigh refr Rippin Tor Rushmere screw Scutchamfly Severndroog Tower Sheppey Shotover Hill Signal Staff Southweald Spire star Steeple Steeple Danbury Stephen's Stoke Stow telescope Tillingham Trevose Head triangles Triptree Wendover Westbury White Horse Hill Whiteham Hill Windmill Zenith dist Zenith distance Zenith Sector
Page 97 - Head, for determining the length of a degree of a great circle perpendicular to the meridian. The truth of the deduction drawn from those observations rests on their accuracy; and it can scarcely be deemed presumptuous to assert, that an error of more than 1" cannot have existed in either of the angles.
Page 94 - ... deflection existed at Dunnose; as the deviation of it towards the north, from a deficiency of matter towards the channel, would tend to diminish the inequality between the lengths of the two degrees. This will be evident, on consideration. I am therefore disposed to believe that the plumb-line waá drawn towards the south, from the action of matter, both at the northern extremity of the arc and at Arbury Hill, but more particularly at the firstmentioned station.
Page 183 - An Account of the Measurement of an Arc of the Meridian, extending from Dunnose, in the Isle of Wight, Latitude 50° 37
Page 93 - The length of the degree at the middle point (51° 3.5' 18") between the southern extremity of the arc and Arbury Hill, is 60864 fathoms; which is greater than the above, and exceeds it by 44 fathoms. But this degree, admitting the earth to be an ellipsoid, with the ratio of its axes as 229 to 230, should be about 10 fathoms less. If the measurement of the...
Page 93 - From this measurement it appears, that the length of a degree on the meridian, in latitude 52° 2' 20", is 60820 fathoms. This conclusion is deduced from the supposition of the whole arc subtending an angle of 2° 50' 23",38 in the heavens, and a distance of 1036337 feet on the surface of the earth. The length of the degree at the middle point (51° 35' 18") between the southern extremity of the arc and Arbury Hill, is 60864.
Page 94 - ... of two stars, north and south of the zenith, at the greatest distances my arc would admit of. But, to return, if there be an error in the amplitude of the total arc, from a deflection of the plumb-line at either of the stations, it is not probable that any such deflection existed at Dunnose; as the deviation of it towards the north, from a deficiency of matter towards the channel, would tend to diminish the inequality between the lengths of the two degrees. This will be evident, on consideration....
Page 183 - London: / Published by W. Faden, Geographer to His / Majesty, and to His Royal Highness the Prince / of Wales, Charing Cross.
Page 94 - Arbury Hill, but more particularly at the firstmentioned station. If this were partly the case, and both Dunnose and Arbury Hill were free from any such prevailing cause, the total arc must be too great, if taken at 2° 50' 23",38, by about 8", nearly answering to 2" on each degree. A deviation of 8" from the true vertical, is a large quantity; nor can the cause of it be assigned, unless it be also supposed, that the matter producing that deflection extends in a southern direction beyond Arbury Hill....
Page 193 - ... attend the placing of the sector at intermediate stations; as the arc would be found running, almost every where, through a country abounding with hills, considerable both in magnitude and number. • Under this consideration, I determined to measure a portion of the meridian which proceeds from Dunnose to the mouth of the Tees ; because, from inquiry, I had reason to suppose it the longest meridional arc in Britain, free from any apparent obstruction. And I was led to select Dunnose for one...
Page 94 - ... consideration. I am, therefore, disposed to believe, that the plumb line was drawn towards the south from the action of matter, both at the north extremity of the arc and at Arbury Hillt, but more particularly at the first. If this were partly the case, and both Dunnose and Arbury Hill were free from such prevailing cause, the total arc must be too great if taken at 2° 50' 23",38, by about 8", nearly answering to 2