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 2W. Bulmer and Company, 1801 |
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Page 19
... ground . The great theodolite was then placed over the stake , and the instrument accurately adjusted over the dot . A diaphragm , whose aperture was an inch , was then put over the object - glass of the transit telescope , which was ...
... ground . The great theodolite was then placed over the stake , and the instrument accurately adjusted over the dot . A diaphragm , whose aperture was an inch , was then put over the object - glass of the transit telescope , which was ...
Page 20
... ground , with its centre nearly under the cross wires ; after which , a pin was moved on the surface of the peg , as directed by a person looking through the telescope , till it came to that point at which it bisected the angle formed ...
... ground , with its centre nearly under the cross wires ; after which , a pin was moved on the surface of the peg , as directed by a person looking through the telescope , till it came to that point at which it bisected the angle formed ...
Page 21
... ground might be discovered proper for so confined a purpose . The contrary , however , being the case , the party returned to London in October . Between 41 とこ Y point dan digjellati ART . IV . Angles taken in the Year 1798 At Wrotham ...
... ground might be discovered proper for so confined a purpose . The contrary , however , being the case , the party returned to London in October . Between 41 とこ Y point dan digjellati ART . IV . Angles taken in the Year 1798 At Wrotham ...
Page 30
... ground about Nettlebed was formerly examined by us , it appeared difficult to carry on the triangles from Bagshot Heath towards the northward ; because no spot could be found near the former , from which the Chiltern range could be seen ...
... ground about Nettlebed was formerly examined by us , it appeared difficult to carry on the triangles from Bagshot Heath towards the northward ; because no spot could be found near the former , from which the Chiltern range could be seen ...
Page 37
... Ground near Tharfield Tower and Kinsworth 23 59 30 32 5 52 11,5 } 3 31 166 4 44546,25 At Lidlington . Kinsworth and Bow Brickhill Brill and Epwell 22,75 22,25 25,25 68 16 19 At Crouch Hill . At Stanmore . Wendover and Kinsworth Pen ...
... Ground near Tharfield Tower and Kinsworth 23 59 30 32 5 52 11,5 } 3 31 166 4 44546,25 At Lidlington . Kinsworth and Bow Brickhill Brill and Epwell 22,75 22,25 25,25 68 16 19 At Crouch Hill . At Stanmore . Wendover and Kinsworth Pen ...
Common terms and phrases
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 depr distance at Dunnose Ditto Dover Court Draconis Dundon Beacon Dundry Epwell feet Flagstaff Frierning Gravesend Gringley Hadleigh Halstow Hatfield Broad Oak Heath Heathersedge Hensbarrow Herculis Highbeech Highclere Kinsworth Langdon Hill Lansdown Lavenham length Lidlington Lillyhoe Limb 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 Spheri Spire Steeple Steeple Danbury Stoke Stow telescope Tillingham Trevose Head triangles Triptree Wendover Westbury White Horse Hill Whiteham Hill Windmill Zenith dist Zenith distance Zenith Sector
Popular passages
Page 103 - 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 102 - ... 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 189 - An Account of the Measurement of an Arc of the Meridian, extending from Dunnose, in the Isle of Wight, Latitude 50° 37
Page 101 - 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 101 - 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 102 - ... 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 189 - London: / Published by W. Faden, Geographer to His / Majesty, and to His Royal Highness the Prince / of Wales, Charing Cross.
Page 102 - 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 102 - ... 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