He also became interested in earthquakes while in Japan, and was one of the founders of the Seismological Society of Japan (SSJ). During his time in Japan, he also gave public lectures on various scientific topics to general audiences in temples and in theaters.

Returning to Ohio in 1881, Mendenhall was instrumental in developing the Ohio State Meteorological Service. He devised a system of weather signals for display on railroad trains. This method became general throughout the