Zetetic Astronomy, by 'Parallax' (pseud. Samuel Birley Rowbotham), , at sacred-texts.com
Another "proof" of the earth's rotundity is supposed to be found in the fact that mariners by sailing continually
due east or west, return home in the opposite direction. This is called "The Circum-navigation of the Globe." Here, again, a supposition is involved, viz., that on a globe only can a ship continue to sail due east and come home from the west, and vice versâ. But when the process or method adopted is understood, it will be seen that a plane can as readily be circum-navigated as a sphere.
In the following diagram, fig. 86, let N, represent the. northern centre, near to which lies the "magnetic pole." Then
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the several arrows marked A, S, are all pointing northwards; and those marked E, W, are all due east and west. It is evident from the diagram, that A, S, are absolute directions--north and south; but that E, W, east and west, are only relative, that is they are directions at right angles to north and south. If it were not so then, taking the line N, A, S, as representing
the meridian of Greenwich, and W, E, on that meridian as due east and west, on moving due west to the meridian 3, 4, N, it is evident that a vessel represented by the arrow 1, 2, would be at angle with the meridian 3, 4, N, much greater than 90 degrees, and if it continued to sail in the same straight line 2, 1, 5, it would get farther and farther away from the centre N, and therefore could never complete a path concentric with N. East and west, however, are directions relative to north and south. Hence, on a mariner arriving at the meridian 3, 4, N, he must of necessity turn the head of his vessel in the direction indicated by the arrow 6, 7, and thus continuing to keep the vessel's head square to the compass, or at right angles to north and south, he will at length arrive at 90 degrees of meridian from N, A, S, when the head of the vessel will be in the direction of E, W, 8. Continuing his course for 90 degrees more his path will be E, W, 9. The same course continued will in the next 90 degrees become E, W, 10, and on passing over another 90 degrees the ship will have arrived again at the meridian of Greenwich N, A, S, having then completed a circle.
Hence it is evident that sailing westerly, or in a direction square to the compass, on passing from one meridian to another, the path must of necessity be an arc of a circle. The series of arcs on completing a passage of 360 degrees form a circular path concentric with the magnetic pole, and necessarily, on a plane surface, brings the ship home from the east; and on the contrary, sailing out east, the vessel cannot do otherwise than return from the west.
A very good illustration of the circum-navigation of a plane will be seen by taking a round table, and fixing a pin in the centre to represent the magnetic pole. To this central pin attach a string drawn out to any distance towards the
edge of the table. This string may represent the meridian of Greenwich, extending due north and south. If now a pencil or other object is placed across, or at right angles to the string, at any distance between the centre and the circumference of the table, it will represent a vessel standing due east and west. Now move the pencil and the string together in either direction, and it will be seen that by keeping the vessel (or pencil), square to the string it must of necessity describe a circle round the magnetic centre and return to the starting point in the opposite direction to that in which it first sailed.
If it is borne in mind what is really meant by sailing due east or due west, which practically is neither more nor less than keeping the head of a ship at right angles to the various meridians over which it sails, there can be no difficulty in understanding how it is that the path of a circumnavigator is the circumference of a circle, the radius of which is the latitude or distance of the ship from the centre of a plane. But if, in addition to this, the leading facts connected with the subject are considered, it will be seen that the circumnavigation of a globe by the mariners' compass is an impossibility. For instance, it is known that the "dipping needle" is horizontal or without "dip" at the equator; and that the "dip" increases on sailing north and south: and is greatest at the magnetic centre.
Let C, fig. 87, represent a dipping needle on the "equator"
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of a globe. A mere inspection of the diagram is sufficient to make it demonstrated that the needle C cannot be horizontal, and at the same time pointing towards the north pole N. If a ship sailed east or west on the equator where the compass is horizontal, it is evident that its north or south end would describe a circle in the heavens equal in magnitude to the circumference of the earth at the equator--as shown by D, E, F.
If any small object to represent a ship is placed on the equator of an artificial globe and kept at right angles to the meridian lines, it will at once be seen that it cannot be otherwise than as above stated; and that the two facts that the compass always points towards the pole and yet on the equator lies without dip, cannot possibly co-exist on a globe. They do co-exist in nature, and are well ascertained and easily proved to do so, therefore the earth cannot possibly be a globe. They can co-exist on a plane with a northern or central region: they do beyond doubt
co-exist, therefore, beyond doubt the earth is a plane. So far, then, from the fact of a vessel sailing due west coming home from the east, and vice versâ, being a proof of the earth's rotundity, it is simply a result consistent with and dependent on its being a plane. Those who hold that it is a globe because it has been circumnavigated, have an argument which is logically incomplete and fallacious. This will be seen at once when it is placed in the syllogistic form:--
It has been shown that a plane can be circumnavigated, and therefore the first or major proposition is false; and being so, the conclusion is equally false.
This part of the subject furnishes a striking instance of the necessity of at all times proving a proposition by direct and independent evidence; instead of quoting a given result as a proof of what has previously been only assumed. But a theory will not admit of this method; and therefore the Zetetic process--inquiry before conclusion--is the only course which can lead to simple unalterable truth. Whoever creates or upholds a theory, claims or adopts a monster which will sooner or later betray and enslave him, and make him ridiculous in the eyes of practical observers.
223:1 "Scientific Review." April, 1866. Page 5.