The Dunkerque Light, on the north coast of France (see p. 71), is 194 feet high, and visible 28 statute miles. The ordinary calculation will show that it ought to be 190 feet below the horizon!
The Goulfar Bay Light, on the west coast of France, is said at page 77, to be visible 31 statute miles, and to have an altitude at high water of 276 feet, at the distance given it ought to be 210 feet below the horizon!
At page 78, the Cordonan Light, on the River Gironde, west coast of France, is given as being visible 31 statute miles, and its altitude 207 feet, which would give its depression below the horizon as nearly 280 feet!
The Light at Madras (p. 104), on the Esplanade, is 132 feet high, and visible 28 statute miles, whereas at that distance it ought to be beneath the horizon above 250 feet!
The Port Nicholson Light, in New Zealand, erected in 1859 (p. 110), is visible 35 statute miles, the altitude is 420 feet above high water, and ought, if the water is convex, to be 220 feet below the horizon!
The Light on Cape Bonavista, Newfoundland, is 150 feet above high water, and is visible 35 statute miles (p. 111), this will give on calculation for the Earth’s rotundity, 491 feet that the Light should be below the horizon!
Many other cases could be given from the same work, shewing that the practical observations of mariners, engineers, and surveyors, entirely ignore the doctrine that the Earth is a globe. The following cases taken from miscellaneous sources will be interesting as bearing upon and leading to the same conclusion. In the Illustrated London News of Oct. 20, 1849, an engraving is given of a new Lighthouse erected on the Irish coast, The accompanying descriptive matter contains the following sentence:—“Ballycotton Island rises 170 feet above the level of the sea; the height of the Lighthouse is 60 feet including the Lantern; giving the light an elevation of 230 feet, which is visible upwards of 35 miles to sea.” If the 35 miles are nautical measure the distance in statute measure would be over 40 miles; and allowing the usual distance for the horizon, there would be 36 miles from thence to the Lighthouse. The square of 36 multiplied by 8 inches amounts to 864 feet; deduct the total altitude of the Lantern, 230 feet, and the remainder, 634 feet, is the distance which the Light of Ballycotton ought to be below the horizon!
In the Times newspaper of Monday, Oct. 16, 1854, in an account of her Majesty’s visit to Great Grimsby from Hull, the following paragraph occurs:—“Their attention was first naturally directed to a gigantic tower which rises from the centre pier to the height of 300 feet, and can be seen 60 miles out at sea.” The 60 miles if nautical, and this is always understood when referring to distances at sea, would make 70 statute miles, to which the fall of 8 inches belongs, and as all observations at sea are considered to be made at an elevation of 10 feet above the water, for which four miles must be deducted from the whole distance, 66 statute miles will remain, the square of which multiplied by 8 inches, gives a declination towards the tower of 2,904 feet; deducting from this the altitude of the tower, 300 feet, we obtain the startling conclusion that the tower should be at the distance at which it is visible, (60 nautical miles,) more than 2,600 feet below the horizon!
The only modification which can be made or allowed in the preceding calculations is that for refraction, which is considered by surveyors generally to amount to about ¹⁄₁₂th of the altitude of the object observed. If we make this allowance it will reduce the various quotients by ¹⁄₁₂th, which is so little that the whole will be substantially the same. Take the last quotation as an instance—2,600 feet divided by 12 gives 206, which deducted from 2,600 leaves 2,384 as the corrected amount for refraction.