FIG. 42.
If a good theodolite is placed on the summit of Shooter's Hill, in Kent, and levelled, the line of sight, on being directed to Hampstead Hill, will cut the cross on St. Paul's Cathedral, and fall upon a part of Hampstead Hill, the altitude of which is the same as that of Shooter's Hill. The altitude of each of these points is 412 feet above the Trinity high water mark, at London Bridge. The distance from Shooter's Hill to St. Paul's Cathedral is 7 statute miles, and from St. Paul's to Hampstead Hill, 5 miles. If the earth is a globe, the line of sight from the
[paragraph continues] "levelled" theodolite would be a tangent, below which St. Paul's cross would be 32 feet, and Hampstead Hill 96 feet. The highest point of Hampstead Hill is 430 feet, which we find, on making the proper calculation, would be 78 feet below the summit of Shooter's Hill; whereas, according to the Ordnance Survey, and as may be proved by experiment, the three points are in the same direct line; again demonstrating that the earth is a plane.
The diagrams, figs. 42 and 43, will show the difference
between the theory of rotundity and the results of actual survey. A, represents Hampstead Hill; C, St. Paul's cross; B, Shooter's Hill; and D, D, the datum line--the Trinity high water mark. In fig. 43, A, B, C, and D, D, represent the same points respectively as in fig. 42.
In the account of the trigonometrical operations in France, by M. M. Biot and Arago, it is stated that the light of a powerful lamp, with good reflectors, was placed on a rocky summit, in Spain, called Desierto las Palmas, and was distinctly seen from Camprey, on the Island of Iviza. The elevation of the two points was nearly the same, and the distance between them nearly 100 miles. If the earth is a globe, the light on the rock in Spain would have been more than 6600 feet, or nearly one mile and a quarter, below the line of sight.
"The length of some of the sides of the great triangles (in the English survey) is upwards of 100 miles; and many means were employed to render the stations visible from each other at such great distances. The oxy-hydrogen, or Drummond's Light, was employed in some instances; but a heliostat, for reflecting the sun's rays in the direction of the distant observer, was more generally and successfully employed. Lieutenant-Colonel Portlock, R.E., who observed the station on Precelly, a mountain in South Wales, from the station on Kippure, a mountain about 10 miles south-west of Dublin--the distance between the stations being 108 miles--says: 'For five weeks I watched in vain; when, to my joy, the heliostat blazed out in the early beams of the rising sun, and continued visible as a bright star the whole day.'" 1
Many other very long "sights" have been taken by surveyors of different countries, which upon a globe of 25,000 miles in circumference, would have been quite impossible; but with the demonstrated fact that the earth is a plane, are practical and consistent.
59:1 Handbook to the Official Catalogue of the Great Exhibition of 1851.
