Page:Popular Science Monthly Volume 37.djvu/713

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695
SKETCH OF THOMAS CORWIN MENDENHALL.

pan: (1) Report on the meteorology of Tokio, 1879; (2) Report on the meteorology of Tokio, 1880; (3) Measurement of the force of gravity at Tokio and the summit of Fujinoyama, 1881; (4) Wave-length of some of the principal lines of the solar spectrum, 1881; The influence of time on the change in resistance of carbon under pressure, American Journal of Science, 1882; Differential resistance thermometer, American Journal of Science, 1885; Report on the Flood Rock explosion, Science, October 1885; On the electrical resistance of soft carbon under pressure, American Journal of Science, 1886; On characteristic curves of composition, read at the American Association for the Advancement of Science meeting, 1886, published in Science, March 1887; Seismoscopes and seismological investigations, read at the meeting of the National Academy of Sciences, 1887, published in American Journal of Science, 1888; On an improved form of quadrant electrometer, read at the meeting of the National Academy of Sciences, 1888; On the intensity of earthquakes, with approximate calculations of the energy involved, Proceedings of the American Association for the Advancement of Science, 1888; On globular lightning, American Meteorological Journal, 1890. A memoir of researches in atmospheric electricity, read before the National Academy of Sciences in 1888, is now in course of publication.

 


 
In the attempt to measure the duration of a flash of lightning, Mr. A. C. Raynard, in Knowledge, regards a recurrent flash as "a very complicated succession of discharges lasting for an appreciable part of a second. The giant discharges which take place during a storm, between irregularly shaped and badly conducting masses, differ materially in character from the flashes produced in a laboratory between good conductors. In the laboratory the whole flow takes place at once. In nature there seems to be a flow or rash succeeded by a dribble, which ceases or nearly ceases, and commences again and again, flow after flow rushing down the same path until the potential along the line of discharge is realized." The appearance of "ribbon-flashes" in some of the photographs is supposed to be due to unsteadiness or imperfections in the instruments. The present greater proportion than formerly existed of men who are active and vigorous after passing seventy years of age, and all the way even up to ninety, denotes one of the brighter phases of our civilization. The fact that such vigor is associated with different physical types, both suggests that there may be a general origin for it, and feeds the hope that it may partly depend on personal conduct. Dr. B. W. Richardson advises that the preparation to secure long life may begin with the training of children, by protecting them against mental disturbance as well as physical hardship; and may be carried out in more mature life by combining, with hygienic living, healthful activity of mind with lively interest in all things that make for good, while restraining or avoiding passion, undue excitements, and unlovely qualities.