©. G. Rockwood, Jr.—Japanese Seismology. 471 
was the attempt by Dr. Verbeck in 1873 to support a heavy 
planed block of wood upon four crystal balls, these resting 
upon a polished marble slab carefully leveled. The block was 
then in neutral equilibrium and a pencil attached to it would 
leave a record of the motion upon a paper fastened to the slab 
beneath. Such a record was found to be too minute to be of 
service, and an important aim of later devices has been to pro- 
cure in some way an enlarged record of the earth motion. This 
has been accomplished, in two ways: by employing an indicat- 
a paper read before the German Asiatic Society of Tokio in 
June, 1878, and printed in the Transactions of that Society. 
After two years experience a full description of the apparatus 
was published in the Japan Gazette (July 10, 1880).* It con- 
sists of an iron ball weighing forty or fifty pounds, suspended 
by a bundle of silk threads three feet long. At the moment 
of a shock this heavy ball by its inertia remains stationary. 
Beneath the lowest point of the ball, a light vertical indicating 
lever or pendulum is supported by a bar rigidly connected with 
the earth. The fulcrum of this indicating lever is formed by 
a metallic sphere $ inch in diameter, on which it rests by a 
smooth plate forming the top of a short hollow cylinder of the 
same internal diameter as the metallic sphere. he point 
* Transactions Seismological Society of Japan, vol. i, part I, p. 54. 
