It is a well-known fact that the light of the Eddystone lighthouse is often plainly visible from the beach in Plymouth Sound; and sometimes, when the sea is very calm, persons can see it distinctly when sitting in ordinary rowing boats in that part of the Sound which will allow the line of sight to pass between Drake’s Island and the western end of the Breakwater. The distance is 14 statute miles. In a list of lighthouses in a work called “The Lighthouses of the World,” by A. G. Findlay, F.R.G.S., published in 1862, by Richard H. Lawrie, 53, Fleet Street, London, it is said, at page 28:--“In the Tables the height of the flame above the highest tide high water level is given, so that it is the _minimum_ range of the light; to this elevation 10 feet is added for the height of the deck of the ship above the sea. Besides the increased distance to which low water will cause the light to be seen, the effect of refraction will also sometimes increase their range.” In the “Tables” above referred to, at page 36 the Eddystone light is said to be visible 13 miles. But these 13 miles are nautical measure; and as 3 nautical miles equal 3¹⁄₂ statute miles, the distance at which the Eddystone light is visible is over 15 statute miles. Notwithstanding that the Eddystone light is actually visible at a distance of 15 statute miles, and admitted to be so both by the Admiralty authorities and by calculation according to the doctrine of rotundity, very often at the same distance, the lantern is not visible at an elevation of 4 feet from the water; showing that the law of perspective, previously referred to, is greatly influenced by the state of the surface of the water over which the line of sight is directed. A remarkable illustration of this influence is given in the _Western Daily Mercury_, published in Plymouth, of October 25, 1864. Several discussions had previously taken place at the Plymouth Athenæum and the Devonport Mechanics’ Institute, on the true figure of the Earth; subsequent to which a committee was formed for the purpose of making experiments bearing on the question at issue. The names of the gentlemen as given in the above-named journal were “Parallax” (the author of this work), “Theta” (Mr. Henry, a teacher in Her Majesty’s Dock-yard, Devonport), and Messrs. Osborne, Richards, Rickard, Mogg, Evers, and Pearce, all of Plymouth. From the report published as above stated, the following quotation is made:--Observation 6th: “_On the beach, at 5 feet from the water level, the Eddystone was entirely out of sight_.”