Why was it that at the turn of the century, the Geodetic Survey Departments of both the French and United States governments made certain tests, which upset the Copernican theory, than decided that they should be kept secret? What, actually, were these tests, and should they be repeated today, under the most severe test conditions?
If you've ever watched a bricklayer at work, you've seen him use a plumb bob to determine the perpendicular so that his wall will be erect and straight. A plumb bob is simply a weight suspended on the end of cord. It acts on the principle of the attraction of gravity, or mass, and the weight always points toward the center of gravity, which in the case of spherical Earth is its exact center. A line formed by the cord of a plumb bob is at precisely a right angle from the horizontal.
It is a division of a plane surface into two 90° angles. By simply laying his bricks parallel to the line of the plumb bob, the bricklayer builds a wall that is precisely erect. If he did not use a plumb bob, there would be many more leaning towers of Pisa in the world.
However, the plumb bob is not used only to erect buildings, but it is used to measured the distance of the sun or any planet. This is done by measuring a precise horizontal distance on the Earth (which is naturally a curve, because the Earth is round), and since we know the circumference of the Earth, the distance around it, thus we can calculate an exact base for our proposed triangle to be used in measuring the distance of the sun. Then, by us of a sextant, we can "shoot the sun" from both ends of this base line, and get a pair of angles which are slightly less than 90° angles because they are obviously not parallel to the perpendicular as determined by the plumb bob. We know that, given one side of a triangle, and two of its angles, we can calculate the length of the other two sides. Thus, we can tell how far the sun is from the Earth. It isn't quite this simple, because we don't know the precise size of the Earth, and thus, the difference in parallelism of the two perpendiculars we have achieved at both ends of our base line. It should be obvious to the reader that since the plumb bobs point at the center of the earth lines projected into space would continually move further apart.
Thus we have a great interest in exactly how far it is to the center of the Earth, in order to be absolutely sure of our two important angles in figuring interplanetary distances.
Sometime prior to 1901, the French Government, wishing to determine more accurately the actual size of the Earth, so that they could revise and refine their calculations regarding the distance to the sun, hit on a way to measure the difference in distance apart at the top of two lines perpendicular to the surface of the Earth and the bottom of those same two lines. They wanted a pair of lines long enough to give them an appreciable measurement . Obviously they could not erect two parallel poles a mile high, but they did feel they could suspend two plumb bobs a mile deep into a mine shaft, and thus be able to measure the distance apart at the top and the distance apart at the bottom, which would be slightly less. They wanted to know exactly how much less. The result of these tests was very strange. So strange that the French Geodetic scientists contacted the scientists of the American Geodetic Survey and conveyed their results to them, with the request that similar tests be conducted in this country. Officially, nothing was done for some years. But in 1901, one of the Geodetic surveyors happened to be working in the vicinity of the Tamarack mines near Calumet, Michigan. He contacted the chief engineer at Tamarack, and informed him of the information transmitted by the French government. Two mine shafts were selected, and plumb lines exactly 4,250 feet long were suspended in each mine. At the end of these lines a sixty pound bob was hung. In order to prevent movement through a horizontal direction, each bob was suspended in a tank of oil placed at the bottom of the mine shafts.
In this way, it was reasoned, magnetic forces could not effect them. The lines used to suspend the bobs were No. 24 piano wires. For twenty-four hours the lines were allowed to hang, so that there would be no possibility of movement from putting them in place still remaining in the lines. The measurements were begun.
It was then that it was discovered that the French Geodetic engineers had not made a mistake.
Careful re-checking proved that the lines, contrary to expectations, were farther apart at the bottom than at the top!
There can be only one implication to such strange result the center of gravity is not, as previously believed, at the center of the Earth, but in fact, it must be above the surface of the Earth, somewhere in Space! If these two lines, formed by the suspended plumb lines, were to be extended upward, they would meet somewhere in the void away from the Earth, and that point, by all the rules of gravitational attraction, should be the center of gravity of this planet! Greatly puzzled, and not a little disturbed, the Tamarack engineer sent for Professor McNair of the Michigan College of Mines. With McNair there to check his results, the experiment was repeated, the measurements gone over again, and both men were convinced that no error had been made. Professor McNair suggested that the plumb bobs be changed to a non-magnetic metal to overcome any possibility of magnetic attraction or repulsion due to a magnetic ore body nearby. But when this was done, the same figures were arrived at. If magnetic influences had been at work, they would have varied with different metals, but they did not.