The Bedford Level experiment is a series of observations carried out along a six-mile (9.7 km) length of the Old Bedford River on the Bedford Level, Norfolk, England, UK, during the nineteenth and early twentieth centuries, to measure the curvature of the Earth. Samuel Birley Rowbotham, who conducted the first observations starting in 1838, claimed he had proven the Earth to be flat flat earth flat earther flat earthers
The Sagnac effect, also called Sagnac interference, named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer. A beam of light is split and the two beams are made to follow the same path but in opposite directions. To act as a ring the trajectory must enclose an area. On return to the point of entry the two light beams are allowed to exit the ring and undergo interference. The relative phases of the two exiting beams, and thus the position of the interference fringes, are shifted according to the angular velocity of the apparatus. In other words, when the interferometer is at rest with respect to the earth, the light travels at a constant speed. However, when the interferometer system is spun, one beam of light will slow with respect to the other beam of light. This arrangement is also called a Sagnac interferometer. Georges Sagnac set up this experiment to prove the existence of the aether that Einstein's theory of special relativity had discarded.
As regards the science of astronomy: at the beginning of the eighteenth century the heliocentric theory was generally considered self- evident. Only an empirical demonstration that would validate the theoretical accomplishments of Kepler (1571-1630) and Newton (1642- 1727) was lacking. Standard astronomical history still holds and teaches that it was James Bradly (1692-1762) who found “the first experimental proof that the earth has a yearly motion, and that Copernicus was right.”Careful analysis of the relevant data, however, shows that this is not true at all, but that on the contrary, Bradley's so-called ”aberration of star light” gave the first experimental disproof of the heliocentric hypothesis. To recall to mind the bare facts: in December 1725 James Bradley and Samuel Molyneux began a prolonged observation of the star Gamma Draconis, which passed almost vertically overhead at their location. For their observations they fixed a telescope to a chimney stack of the Molyneux house in the hope of detecting the eagerly sought-after parallax, thus proving at long last the Copernican theory. Substantially correct, but simply stated, the matter is this: if indeed the earth moves in its orbit around the sun, then the place from which we observe the stars will be continually changing. Therefore, we shall see a nearby star as moving in a small circle against a background of more distant stars (see Figure 1). What is more: looking at such a nearby star A from point M in March, and point S in September, and knowing the distance SM to be about 3x108 km, we can by means of triangulation obtain the distance to A.Now Bradley found that Gamma Draconis indeed does describe a small circle with a radius of 20.5 seconds of arc (20”.5). The problem facing him was how to explain this phenomenon. Did it indeed result from the earth's revolution about the sun, and hence relative to the array of fixed stars? That is, did it show the parallax he had hoped to find or was the motion caused by the sun and stars circling with respect to an earth “at rest?” Bradley was forced to opt for the first alternative, but then had to reject it; for Gamma Draconis did not circle against the backdrop of stars, but all the stars joined in the motion which would imply that they were all at the same distance from earth. In other words, to accept the phenomenon as a parallax would mean re-introducing the discarded medieval concept of a Stellatum, a gigantic shell of stars centered on the sun which revolves about us. Since this was considered to be impossible, another interpretation of the observational facts had to be found. The circlets were decidedly not offering parallaxes, but what, then, did cause them?After pondering the problem for a time, so the story goes, Bradley invented the correct interpretation in 1728 during a sailing trip on the Thames. In doing so, he thought he had solidly established the truth of the Copernican-Newtonian synthesis by means of what he called the ”aberration of starlight.”
Blakeston, Oswell. England's latter-day flatearthists. (The story of a correspondence.) Life and letters, v. 62, July 1949: 9–24.
AP4.L416, v. 62 Bramhall, William. Wilbur Glenn Voliva. In his The great American misfit; 26 bizarre personal histories. New York, C. N. Potter  p. 71–73. port.
CT9990.B7 1982 Carpenter, William. One hundred proofs that the earth is not a globe. [6th ed.] Baltimore, 1885. 39 p.
QB638.C3 1885a Cohen, Daniel. Is the earth flat or hollow? Science digest, v. 72, Nov. 1972: 62–66. col. illus.
Q1.S383, v. 72 Collamore, R. G. S. His pronouncement: a layman's version, a layman's message. Philadelphia, Dorrance  157 p.
Q173.C6 Cook, Frederick H. The terrestrial plane; or, The true figure of the earth. [London, 1908] 64 p.
Held by the British Library under shelfmark 8563. b. 52. Davenport, Walter. "They call me a flathead." Collier's, v. 79, May 14, 1927: 30–31. illus., ports.
AP2.C65, v. 79
"Wilbur Glenn Voliva, the boss of Zion City, knows the world is flat. He can prove it. He doesn't care what you think or what the newspapers say. He's still doing business at the old stand, and business couldn't be better." DeFord, Charles S. A reparation: universal gravitation a universal fake. Fairfield, Wash., Ye Galleon Press  62 p. illus., port.
Reprint of the 3d ed. (New York, Fortean Society, 1931), with a new introduction by Robert J. Schadewald.
"... an attempt to prove that the world is flat." Edgell, William. Does the earth rotate? [London? 1927] 69 p. illus., port. NN Flat city. In Odd and eccentric people. By the editors of Time-Life Books. Alexandria, Va., Time-Life Books  (Library of curious and unusual facts) p. 13–l4. illus., port.
About Wilbur Glenn Voliva. Flat earth. New statesman and nation, new ser., v. 9, Jan. 12, 1935: 35–36.
AP4.N64, s. 2, v. 9
Signed Y. Y.
On the views of Henry Edgell, "the most persistent modern advocate of the theory that the earth is flat," who had just died at the age of 73. Gardner, Martin. Flat and hollow. In his Fads and fallacies in the name of science. [Rev. and expanded ed.] New York, Dover Publications  p. 16–27.
The part of this chapter dealing with flat-earth proponents is about Voliva and the Christian Apostolic Church in Zion, Ill. Gates, David, and Jennifer Smith. Keeping the flat-earth faith. Newsweek, v. 104, July 2, 1984: 12. port.
AP2.N6772, v. 104
On Charles K. Johnson and the International Flat Earth Research Society. Gleason, Alex. Is the Bible from heaven? Is the earth a globe? 2d ed., rev. and enl. Buffalo, N.Y., Buffalo Electrotype and Engraving Co.  xix, 402 p. illus., map, col. plates, ports.
QB638.G56 Goudey, Henry J. Earth not a globe: scientifically, geometrically, philosophically demonstrated. Over 75 arguments and 30 diagrams. Boston, Mass., 1930. 145 p. illus., fold. map.
QB52.G7 Gould, Stephen J. The persistently flat earth. Natural history, v. 103, Mar. 1994: 12, 14–19.
QH1.N13, v. 103
Investigates the relatively recent origin of the notion that scholars of the Middle Ages, with few exceptions, believed the earth was flat. Hampden, John. The new manual of biblical cosmography; or, Outline of the general system of the universe. London, Beaumont  15 p. fold. illus.
QB638.H22 The Infidel globe; or, Scientific witchcraft, the emblem of paganism and the refuge of the atheist. [London?] 1884.  p.
YA 22866 Rare Bk. Coll. Johnson, Gilbert. The book of light, a brief description of the earth, with a map showing its shape. The earth being flat instead of round, the sun is not stationary but moves. Greer, Mo., 1923. 48 p. fold. map.
First published in 1890 (7 p. QB638.J67). Jones, Charles W. The flat earth. Thought, v. 9, Sept. 1934: 296–307.
AP2.T333, v. 9
Finds that educated persons in the Middle Ages knew that the earth is round. Labbie, Edith. The world is flat. In Those eccentric Yankees. Edited by John Lovell. Introd. by Robert Taylor. Camden, Me., Yankee Books  p. 10–13.
About Joseph W. Holden (1816–1900) of Otisfield, Me. Lindsay, Thomas. Astronomical myths—the flat earth. Popular astronomy, v. 6, Sept. 1898: 405–408.
QB1.P8, v. 6 London. Zetetic Society. Chart and compass, sextant and sundial, latitudes and longitudes, plumbline and pendulum, globe or plane? A letter of remonstrance, respectfully addressed to the officers of the Naval and Mercantile Marine of England and America. [London, 1887] 8 p.
Held by the British Library under shelfmark c. 19. (9.). Macht, David I. Science and the Bible. Science, v. 114, Nov. 9, 1951: 505.
Q1.S35, v. 114
Letter commenting on Ray's observations on the shape of the earth as implied by Revelation 7:1. McCready, William D. Isidore, the Antipodeans, and the shape of the earth. Isis, v. 87, Mar. 1996: 108–127. illus.
"That the sphericity of the earth was clearly established in the ancient world is beyond dispute. Apparently unknown to the Babylonians or Egyptians, it was a discovery of Greek astronomy and was generally accepted among natural philosophers by the time of Aristotle. It was the received view of educated Romans as well, including Pliny the Elder. Among Christian thinkers, however, its fortunes are not quite so clear. It was not without significance that the ancient Hebrews, whose views were reflected in Scripture, conceived the earth as a flat disk covered over by the dome of the heavens ... [Isidore's] grasp on the spherical nature of the earth was tenuous at best ..." Michell, John. Loyalists of the flat earth. In his Eccentric lives and peculiar notions. San Diego, Harcourt Brace Jovanovich  p. 21–32. illus., plates, ports.
References (19): p. 234.
The plates follow p. 32; no. – relate to the flat-earth supporters. Moore, Patrick. Better and flatter earths. In his Can you speak Venusian? A guide to the independent thinkers. [Newton Abbot, David & Charles, 1972] p. 16–29. illus.
QB52.M66 1972 Morse, Charles W. Unpopular truth against popular error in reference to the shape of the earth. Boston, C. J. F. Fletcher, Printer, 1913. 78 p. illus., port.
QB281.M8 Proctor, Richard A. A challenge from the earth-flattening society. Knowledge, v. 4, Nov. 30, 1883: 336.
Q1.K7, v. 4 Proctor, Richard A. The earth-flattener's challenge. Knowledge, v. 4, Dec. 14, 1883: 362.
Q1.K7, v. 4 Proofs (so-called) of the world's rotundity, examined in the light of facts and common sense, by "Search Truth." [London, Zetetic Society, 1882?] 2 p. illus.
YA 22774 Rare Bk. Coll.
"... the world is as God made it, a circular and motionless plane, with the Sun, Moon, and Stars revolving at very moderate distances above it ..." Quinlan, John E. The earth a plane. London 
Held by the British Library under shelfmark 8563. b. Randi, James. Flat Earth Society. In his An encyclopedia of claims, frauds, and hoaxes of the occult and supernatural. James Randi's decidedly skeptical definitions of alternate realities. New York, St. Martin's Press  p. 97–98.
BF1407.R36 1995 Ray, Cyrus N. The rectangular earth. Science, v. 113, May 25, 1951: 610.
Q1.S35, v. 113
Letter calling attention to Revelation 7:1 which suggests that the earth's shape is that of a flat rectangle. Really, is it flat? Moody Bible Institute monthly, v. 30, Sept. 1929: 6.
BR1.M6, v. 30 [Rowbotham, Samuel B.] Zetetic astronomy. A description of several experiments which prove that the surface of the sea is a perfect plane, and that the earth is not a globe. Being the substance of a paper read before the Royal Astronomical Society on the evening of Dec. 8, 1848. By ‘Parallax' [pseud.] Birmingham, W. Cornish, 1849. 16 p. illus.
QB638.R87 [Rowbotham, Samuel B.] Zetetic astronomy. Earth not a globe. An experimental inquiry into the true figure of the earth, proving it a plane, without orbital or axial motion, and the only known material world; its true position in the universe, comparatively recent formation, present chemical condition, and approaching destruction by fire, &c., &c. By "Parallax" [pseud.] The illus. by George Davey. 3d ed., rev. and enl. London, Day, 1881. 430 p. illus. CaBViP; CtY; ICJ Russell, Jeffrey B. The flat error: the modern distortion of medieval geography. In Mediaevalia, a journal of medieval studies. v. 15; 1989. Binghamton, Center for Medieval and Early Renaissance Studies of the State University of New York, 1993. p. –353.
CB351.M38, v. 15
"I first review the evidence that educated medieval people knew the shape of the planet, go on to show how and why the ‘Flat Error' developed, and end with some suggestions about the precarious nature of historical knowledge." Schadewald, Robert J. The flat-out truth; earth orbits? Moon landings? A fraud! says this prophet. Science digest, v. 88, July 1980: 58–63. port.
About Charles K. Johnson, president of the International Flat Earth Research Society. Schadewald, Robert J. He knew earth is round, but his proof fell flat. Illus. by W. B. Park. Smithsonian, v. 9, Apr. 1978: 101–102, 104, 106–108, 110, 112–113. illus. (part col.)
AS30.S6, v. 9
"A renowned English naturalist [Alfred Russel Wallace] seeking to convince a nonbeliever, won argument, lost the money." Scott, David W. Terra firma: the earth not a planet, proved from scripture, reason, and fact. London, Simpkin, Marshall, Hamilton, Kent, 1901. xvi, 288 p. illus., fold. map.
CtY; MdBJ Serland, F. S. Did the older ecclesiastical writers deny the sphericity of the earth? American Catholic quarterly review, v. 43, Apr. 1918: 340–343.
AP2.A332, v. 43
Points out "that Venerable Bede in the first half of the eighth century knew and taught the sphericity of the earth" and that this knowledge was not dependent on Islamic learning. Shippey, Chester M. Answers to the common "proofs" that the earth is a globe. Leaves of healing, v. 66, May 10, 1930: 138–142, 184.
BX7401.L3, v. 66 Shippey, Chester M. The true shape of the earth. Leaves of healing, v. 66, May 10, 1930: 158–160, 162–166, 168–173, 175.
BX7401.L3, v. 66 Sifakis, Carl. Voliva, Wilbur Glenn (1870–1942): king of the flat earthers. In his American eccentrics. New York, Facts on File Publications  p. 226–229. port.
CT9990.S53 1984 Sisk, John P. The view from the edge; on the necessity of the flat earth. Harper's, v. 258, Mar. 1979: 127–129.
AP2.H3, v. 258
On the International Flat Earth Research Society. Smith, Carl Albert. Is the earth a whirling globe? 2d ed., rev. and enl. Northampton  112 p.
Held by the British Library under shelfmark 8562. aaa. 35. Wallace, Alfred Russel. [Hampden and the flat earth] In his My life, a record of events and opinions. v. 2. New York, Dodd, Mead, 1905. p. 381–393. illus.
QH31.W2A, v. 2 Wallace, Irving. In defense of the square peg. In his The square pegs; some Americans who dared to be different. New York, A. A. Knopf, 1957. p. 3–24.
Discusses Wilbur Glenn Voliva on p. 3–8. Where are they now? The flat earthers. Newsweek, v. 73, Jan. 13, 1969: 8. port.
AP2.N6772, v. 73
About the International Flat Earth Research Society, then based in Dover, England. The portrait is of Samuel Shenton, the society's general secretary. White, Andrew D. The form of the earth. In his A history of the warfare of science with theology in Christendom. v. 1. New York, D. Appleton, 1896. p. 89–98.
BL245.W5, v. 1 White, Arthur V. The shape of the earth; some proofs for the spherical shape of the earth given in astronomical and geographical text-books examined, and shown to be unsound. [Toronto?] University of Toronto Alumni Association, 1909.  p. illus.
Reprinted from the University Monthly, Mar. 1909. [Winship, Thomas] Zetetic cosmogony; or, Conclusive evidence that the world is not a rotating-revolving-globe, but a stationary plane circle. By Rectangle [pseud.] 2d ed., enl. Durban, Natal, T. L. Cullingworth, 1899. 192 p.
First published in 1897 (46 p. QB638.W769). Wise, Carl S. The Bible and the earth's shape. Science, v. 113, Feb. 2, 1951: 128.
Q1.S35, v. 113
Declares that "the Bible itself nowhere states that the earth is flat." Woofson, H. Ossipoff. The flat earth and her moulder. Knowledge, v. 5, Mar. 28–Apr. 4, 1884: 213, 233.
Q1.K7, v. 5
The former secretary of the Zetetic Society "promises to show the nature of the deceptions practised by some at least among the advocates of the flat-earth theory."