. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 204 RECENT STUDIES IX GRAVITATION. Cavendish experiment turned from a horizontal into a vertical plane, and in which the torsion balance is replaced by the common balance. This method occurred about the same time to the late Prof. IT. Jolly and myself. The principle of my own experiment" will be sufficiently indicated by fig. 3. A big bullion balance with a 4-foot beam had two lead spheres. A B, each about 50 pounds in weight, hang- in
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 204 RECENT STUDIES IX GRAVITATION. Cavendish experiment turned from a horizontal into a vertical plane, and in which the torsion balance is replaced by the common balance. This method occurred about the same time to the late Prof. IT. Jolly and myself. The principle of my own experiment" will be sufficiently indicated by fig. 3. A big bullion balance with a 4-foot beam had two lead spheres. A B, each about 50 pounds in weight, hang- ing from the two ends in place of the usual scale pans. A large lead sphere, M. 1 foot in diameter and weighing about 350 pounds, was brought first under one hanging weight, then under the other. The pull of the lead sphere acted first on one side alone and then on the. Common balance experiment (Poynting). other so that the tilt of the balance beam when the sphere was moved round was due to twice the pull. By means of riders the tilt and there- fore the pull was measured directly as so much increase in weight. This increase, when the sphere was brought directly under the hanging weight with 1 foot between the centers, was about one-fifth mgm. in a total weight of 20 kilograms, or about I in 100,000,000. If. then, a sphere one foot away pulls with 1 108 of the earth's pull, the earth being on the average 20,000,000 feet away, it is easy to see that the earth's mass is calculable in terms of the mass of the sphere, and its aPhil. Trans. 182, 1891, A, p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Smithsonian Institution. Board of Regents; United States National Museum. Report of the U. S. National Museum; Smithsonian Institution. Report of the Secretary. Washington : Smithsonian Institution
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