Rn Ce Ce ae ee ee ae nee Te ee 
C. G. Rockwood, Jr.—Japanese Seismology. 473 
thus able to move in a vertical as well asa horizontal direction, 
and the amount of this vertical motion is recorded by attaching 
to the upper part of the pendulum a fine thread which turns a 
small pulley above and thereby moves a long pointer. To 
ring is crossed by a diametral bar, at the middle of which are 
graph. Here a pair of exactly similar hollow cylinders of 
metal are placed on a smooth level plane, with their axes hori- 
zontal and at right angles. Being thus in neutral equilibrium 
they are free to roll, and their motions are recorded by the 
magnifying levers whose fulerams are upon a fixed support 
above the cylinders and whose long’arms write upon a moving 
drum or plate. 
Still another arrangement, the Bracket Ring Seismograph, 
which has already done good service, is a modification of Zoll- 
*A new form of Pendulum Seismograph. Transactions Seismolog. Soc. of 
Japan, vol. i, part I, p. 38. 
gpm Phil. Mag., V, vol. xii, Sept., 1881. 
