SEEING THE EARTH REVOLVE.

Lake County Press, Issue 1064, 14 May 1903, Page 3

SEEING THE EARTH REVOLVE.

The most brilliant experiment evei j made in astronomy is abort to b( repented by the Astronomical Society of Paris. It is known to all scientists as "the pendulum experiment of Foucault," and its purpose is to prove the circular movement ol the earth. Foucault, who first concieved the idea, was the most ingenious of all French scientists ol the generation just passed. In 1851, when he was a pupil of Arago, lu asserted that if a long pendulum • were suspended inside a very high building and put in motion, the } movement of the earth from west tc east would be shown by the changl ing of the surfaces underneath the pendulum. He illustrated his idea by swinging a pendulum above a slowly revolving table. It was seen that the twisting of the wire did not alter the direction in which the pendulum was swinging, and Foucault's idea as a theory was clearly demonstrated. After overcoming a great many difficulties, Faucault at last obtained permission to trj' his idea in the ! Pantheon, at Rome. He asserted that his theory could be made clear to every one who had eyes to see the proofs. WHERE IT IS DONE. The dome of this famous building, tin; Pantheon, is 285 ft. in height and the ceiling in the main hall is 200 ft. from the floor. Foucault, j then an enthusiastic young scientist, | managed to fasten a steel wire to | the centre' of the ceiling and attached a heavy ball of metal to the lower end of the wire. The metal ball was suspended half an inch above a circular, mahogany table, 12ft. in diameter, hollowed out. slightly and i with a little rim of fine sand running | round the edge of it. A needle was inserted in the under ! side of the metal ball, projecting 1 nearly half an inch downwards, so that it almost touched the surface of the table and maelc a line whenever it touched the rim of sand. Pulling the pendulum out beyond the i edge of the table, Foucault fastened jit with a cotton string, and when the wire was perfectly motionless j set lire to the string and released the i pendulum. In a few minutes to his j great, delight, the floor was distinctly seen to move underneath-the ; pendulum. Every time the long pendulum swung through the ridge of sand if made its mark in a new i place. The floor was twisting about 1 at the rate of one revolution every 24 hours, and the unchanging pendulum was marking time with each swing. At once the news was sent round the world that the motion of the : earth could be seen as plainly as the motion of a clock's wheels are shown I by watching its hands. The experij meat created the greatest enlhusI iasm among scientific circles and I placed the young Frenchman among ' the world's greatest astronomers. No history of astronomy is complete to-day without the name of Foucault and the history of the famous pendulum. The Aatronomic&l Society of Paris has chosen the Pantheon as the place where the experiment is to be repeated. In many respects, this ancient building, erecteil 1,929 years ago by one of the Roman Emperors, is the most suitable in Europe. In design the Pantheon re- | sembles a huge cylinder, surmounted j by a lofty dome. Dome and ciclin- I dcr arc each 142£ ft in height. I There are no currents of air to disturb the swaying of a pendulum, as the only window is in the dome and is 30ft. in diameter. The Pantheon is the best preserved of all the ancient buildings in Europe. Originally designed as a heathen temple, i it was, in 607, altered and conse- j crated as a Christian church. There are only two other experiments by which the motion of the earth can be visibly made clear— ! the observations of ships at sea and the dropping of a heavy body from a : great height. When a ship is approaching her masts are seen first ; and her hull last, and when a stone : is dropped from a height of 252 ft. at the equator it will fall lin. out of plumb. The Paris Astronomical Society hopes not only to verify the conclusions of Foucault, but to make new observations which were not possible 50 years ago.—':Sciencc Sittings." '