Abstract
MR. T. C. MENDENHALL of Japan has measured with a so-called “invariable pendulum” the acceleration of gravity at the top of the extinct volcano Fujiyama, which plays so promi nent a part in the mythology and in the art of Japan. The value found for the summit of the mountain was g = 9.7886, whereas at Tokio the value was found to be 9.7984. The average baro metric pressure at the summit was 19.5 inches, the mountain itself being an almost perfectly symmetrical cone of vertical angle 138°, and of a height of 2.35 miles. It rises alone out of a plain of considerable extent, and appears to be composed of a uniform rock of porous nature. Tradition states that the moun tain was thrown up in a single night in the year B.C. 286. The density of the rock in the lump was 1.75, but when reduced to powder the density was 2.5; competent geologists conclude the mean density of the mountain mass to be 2.12. Assuming the mountain to be a cone of semi-vertical angle of 69°, and density 2.12, Mr. Mendenhall calculated its attraction upon a particle placed at the vertex, and comparing it with his result, deduced for the mean density of the earth the value D = 5.77. If how ever the accepted density of the earth as determined by Bailly at 5.67 be adopted, it follows that the mean density of Fujiyama is only 2.08.
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Physical Notes . Nature 23, 441–443 (1881). https://doi.org/10.1038/023441b0
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DOI: https://doi.org/10.1038/023441b0