200 



REPORT — 1898. 



Velocity of Fropagation of EaHh-waves. 



Padua 



Ischia 



Rocca di Pajja . 

 Catania . 

 Rome 



Instruments employed. 



Microseismograph (Vicentini) Pendulum, I'S m. Bob, 50 

 kgs. Free period, 2-4 sees. Multiplication bv indices, 

 70 to 80. 



Horizontal Pendulum. Bob, 12 kgs. Free period, 11 sees. 



Pendulum, 15 m. Bob, 200 kgs. 



Pendulum, 253 m. Bob, 300 kgs. 



Pendulum, 8 m. Bob, 100 kgs. . 



No. 83, February 7, 1897. (B.A. Report, 1897). 



H. M. s. Pts. 2Cmin. 40 sees. Duration, Ihr. 6 mins. 



Horizontal pendulum and photo record. 

 Bifilar pendulum and photo record. 

 Pendulum (Vicentini). 

 Horizontal pendulum, 12 kgs. 

 Horizontal pendulum and photo record. 



Pendulum, 15 m., 250 kgs. 

 Pendulum, 25 m., .300 kgs. 

 Pendulum, 16 m., 200 kgs. 

 Duration by seismograph, 5-47. Slow movement. 



At Ischia the period of the large waves reached 18-5 sees. The natural 

 period of the pendulums in the meridian and at right angles was 12-9 sees, 

 and 16 '4 sees. 



At Rocca di Papa there were also two horizontal pendulums carrying 

 30 kgs., and with periods of 20 sees. The N.S. component commenced at 

 8hrs. 25 mins., and the E.W. component at 8 hrs. 23 mins. 40 sees. 



At Catania the N.W.-S.E. component commenced at 8 hrs. 22 mina. 

 43 sees. ; N.E.-S.W. component commenced at 8 hrs. 27 mins. 49 sees. 



Velocity of Propagation. — For reasons similar to those given for Earth- 

 quake No. lOO, I shall assume that this disturbance had the same origin 

 as No. 100, and that it occurred at least 2 mins. 30 sees, earlier than it was 



