I AM in entire sympathy with Mr. Lambert's plea in NATURE of June 21, p. 889, for further research on earth tides. It is much to be regretted that so little has hitherto been effected in that direction. I only wish our “far-flung” Empire had done its share in investigating geophysical problems connected with the earth's crust. I fancy, however, that the horizontal pendulum would be more easily and cheaply installed in outlying stations than the interferometer apparatus of Michelson and Gale. The Milne-Shaw seismometer can be adapted for the purpose by the addition of a stationary mirror tracing a reference line on the record.