316 Proceedings of the Ohio Academy of Science 
His earliest scientific paper was published in 1870. For the succeed- 
ing thirty years his contributions to the leading scientific periodicals 
were frequent and important. The Proceedings of the A. A. A. S., the 
American Journal of Science, Popular Science Monthly, Science, and 
the U. S. Coast and Geodetic Servey, were principal avenues of pub- 
lication. 
As the first professor of physics of the Ohio State University, the 
pioneer work of equipping and putting into service a laboratory for 
instruction and research fell to him. He began this work in 1873, the 
first man elected to the faculty of the newly organized institution. 
In 1878 he accepted the task of organizing the Physics department 
of the Imperial Universtiy of Japan at Tokio. He also founded the 
meteorological observatory there. His research work in Japan included 
careful measurements of the gravitation constant at Tokio and on the 
summit of Fujiyama, a determination of the density of the earth and 
some very accurate work with a Rutherford grating on the lines of the 
sun’s spectrum. The celebrated astronomer, Professor Young of Prince- 
ton, pronounced these results as extraordinary. He also helped found 
the Seismological Society of Japan, which has done more than any 
other organization to make seismology an exact science. 
In 1881 he returned to this country and resumed his work at Ohio 
State University. In the following year he organized the Ohio State 
Weather Service. His activity in seismology continued after his return. 
In 1884 he became professor in the U. S. Signal Corps at Washington 
and developed instruments for the study of earthquakes. He also 
started C. F. Marvin, a former student of his in Ohio and the present 
distinguished Head of the U. 5S. Weather Bureau, in this same line of 
work. Dr. Mendenhall also began at this time an elaborate study of 
atmospheric electricity. 
In 1886 he became president of the Rose Polytechnic Institute. 
Though a capable administrator he somehow kept up his scientific inves- 
tigations and published four or five scientific papers during his three 
years presidency. The National Academy of Sciences also published a 
large volume on his work during this period in atmospheric electricity. 
In 1889 he was made Superintendent of the U. 5. Geodetic Survey. 
He here developed the famous ‘‘ Mendenhall half-second pendulum,” 
which for more than 25 years continued to do extraordinarily accurate 
work in fifteen Survey stations, and is still relied upon for the most 
exact results. One of these instruments was carried to Alaska, repeat- 
edly landed in a surf boat for observations and when brought back to 
Washington gave the same value for ‘“‘g”’ that it had given before the 
journey, to one part in 5,000,000. The reports and bulletins of the 
Survey contain many of his papers between 1889 and 1894. He was 
also made Superintendent of Weights and Measures and achieved the 
important task of putting our national system of weights and measures 
upon a Metric basis. 
In 1893 he was one of five eminent electricians (chosen by mail 
ballot of 150 leading electrical men) to represent the United States at 
the International Electrical Congress at Chicago. Differences of opinion 
