@article{oai:repository.dl.itc.u-tokyo.ac.jp:00000280, author = {GRAY, THOMAS}, journal = {Transactions of the Seismological Society of Japan}, month = {}, note = {application/pdf}, pages = {145--147}, title = {ON A METHOD OF COMPENSATING A PENDULUM SO AS TO MAKE IT ASTATIC}, volume = {3}, year = {1881} }