SKETCH OF THOMAS COR WIN MENDENHALL. 695 



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 ; Re- 

 port 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 composi- 

 tion, read at the American Association for the Advancement of 

 Science meeting, 1886, published in Science, March 1887; Seis- 

 moscopes 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 elec- 

 trometer, read at the meeting of the National Academy of Sci- 

 ences, 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. Ray- 

 nard, 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 ap- 

 pearance 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 com- 

 bining, with hygienic living, healthful activity of mind with lively interest in all 

 things that make for good, while restraining or avoiding passion, undue excite- 

 ments, and unlovely qualities. 



