THE movements of horizontal pendulums referred to in this note are those which have been observed in Japan and the Isle of Wight. In reports to the British Association on the earthquake and volcanic phenomena of Japan in the years 1883, 1884, 1885, 1887, 1888, 1892, 1893, and 1894, abstracts are given of work which has been carried out in that country in the investigation of earth tremors or pulsations, diurnal waves, and other earth movements. The Report for 1892 describes a pair of extremely light horizontal pendulums, the movements of which, with the aid of mirrors and lenses, were recorded on photographic plates and films, and gives some account of the analysis of the resulting records. The observations were continued during the following year, when it was observed that the direction of earthquake movement in many cases coincided with the direction in which strata had been folded to form mountain ranges bordering the Tokio plain. Another observation was that certain earthquakes had been preceded by an abnormal amount of tilting. During the last year, largely in consequence of the liberality of the Royal Society of London, I have been able to extend these observations, and records have been obtained from horizontal pendulums, each provided with photographic recording apparatns, from nineteen installations. The more important of these installations were as follows. At Tokio in my house, on a massive stone column. At a place 1000 feet distant, in an underground chamber, excavated in the alluvium on a concrete bed. At Kanagawa the observatory was in an artificial cave, driven at a depth of about 50 feet in soft tuff rock beneath its junction with overlying alluvium. At Yokohama two instruments were placed in a cave on the tuff rock, about two feet below its junction with the alluvium. At Kamakura two instruments were placed in a cave on hard tuff, which dips at an angle of 30° north-east.