ON SEISMOLOGICAL INVESTIGATION. 

 Eaethquakes Eecokded at Shidjs, etc.— continued. 



193 



Note.— On February 5, about 9 A.M., when there were slight disturbances in 

 Catania, Catanzaro (Calabria), Rome, and Livorno, and February 18, between 

 16h. 30m. and 17h. 30m., when there were feeble movements recorded at Catania, 

 Ischia, Rocca di Papa, and Rome. The clock driving the photographic film at Shide 

 had stopped. On the 5th it will be observed that a record was obtained on smoked 

 paper. 



Note on the Edinburgh Bifilar, Extracted frrnn, a Letter received from Mr. 

 Thomas 'Heath, of the Royal Observatory, Edinburgh. 



An inspection of the photograph shows but little trace of the diurnal 

 wave. Measurements of the change of position of the light spot for every 

 four hours throughout the month of March 1898 results in an irregular 

 curve, which apparently indicates a slight movement to the north from 

 noon to midnight, and to the south from midnight to noon. Maximum 

 and minimum thermometers are being established in the bifilar room. 



The mean of daily measurements between February 28 and April 2 

 indicate that the new movement of the light spot corresponds to a tilt of 

 l"-74 of the frame. The photographs have not been subjected to the 

 examination necessary to show whether there is a lunar effect. 



The instrument was first mounted in March 1894, at Carlton Hill, 

 and removed to its present site, on Blackford Hill, in October 1895. It 

 was mounted with photo-recording apparatus in August 1896. A second 

 pendulum purchased out of grant from the Scientific Research Committee 

 of the Royal Society was mounted in May 1898. 



1898. 



