Abstract
American Journal of Science January.—A new harmonic analyser, by A. A. Michelson and S. W. Stroud. This is an instrument designed to sum up as many as eighty terms of a Fourier series, or to analyse a given curve into its original series. The pen which traces the curve is worked up and down by a lever controlled by a spring. This spring is stretched by an ex-centric, which imparts a “simple harmonic” variation to the force. The stretching is resisted by another spring. Eighty such elements are connected together, with one resisting spring to counterbaiance the sum of the elementary springs. The pen therefore moves in accordance with the sum of the elementary periodic motions. The authors obtain by this machine the mathematical series representing the profile of a human face.—Anew form of physical pendulum, by J. S. Stevens. The error introduced into the ordinary physical pendulum by the fact that the knife-edges and clamp affect the moment of inertia may be eliminated by boring a hole into the rod and screwing the knife edges a little way in, so that they offset the mass of brass bored out.—The Protostegan plastron, by G. R. Wieland.
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Scientific Serials. Nature 57, 333 (1898). https://doi.org/10.1038/057333a0
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DOI: https://doi.org/10.1038/057333a0