the earth's figure are likely to be presented at an early day. As Superintendent of Weights and Measures, Prof. Mendenhall enters upon another field of duty for which his work in the past has been a preparation. He has long borne a prominent part among the teachers who have pressed and still continue to press the metric system upon the American public. He is an active member of the American Metrological Society, and has repeatedly, on the platform and through the press, taken occasion to impeach the current irrational medley of pounds avoirdupois and troy; of grains, gallons, feet, and bushels.
Prof. Mendenhall has uncommon gifts as a lecturer; his masterly expositions of physical themes continue to be given despite the pressure of official duties. At the Cooper Institute in New York, the Lowell Institute in Boston, the Peabody Institute in Baltimore, the Mechanics' Institute in Cincinnati, the Brooklyn Institute, and in other of the chief popular lyceums of the country, he has been greeted by large audiences. The honorary degree of Ph. D. was conferred on him by the Ohio State University in 1878, and that of LL. D. by the University of Michigan in 1887. In the latter year he was chosen a member of the National Academy of Sciences. He was elected a member of the American Association for the Advancement of Science at the Indianapolis meeting in 1871, and was advanced to the grade of Fellow in 1874. In 1882, at the Montreal meeting, he presided over the Section of Physics. His address on that occasion was a forcible plea for physics in education, presenting a judicious view of the value of guidance when students attempt original research. In 1888 he was chosen President of the Association, and in that capacity at last year's meeting, in Toronto, won golden opinions on all hands. At the approaching meeting in Indianapolis he will, it is understood, take for the theme of his address, as retiring president, The Relation of Science and Scientific Men to the General Public.
In 1887 he contributed the first volume to The Riverside Science Series, A Century of Electricity. A revised and enlarged edition of this capital popular treatise has been issued this year. From among his numerous contributions to scientific publications we select: On the time required to communicate impressions to the sensorium and the reverse, American Journal of Science, 1871; On the heaping of liquids, American Journal of Science, 1873; An improvement on Bunsen's method for specific gravity of gases, Proceedings of the American Association for the Advancement of Science, 1878; Temperature and index of refraction, American Journal of Science, 1876; Co-efficient of expansion of a diffraction grating, American Journal of Science, 1881; Memoirs of the. Scientific Department of the University of Tokio, Ja-
