Charles Davison—British Earthquakes. 299 
Budock (Observer, Mr. R. Mollett, awakened by the earthquake). 
—The sound like that of an explosion at some distance, followed by 
a distant rumbling sound lasting about 30 seconds. 
St. Ives (Observer, Rev. J. Balmer Jones).—A tremulous motion, 
half felt, half heard, lasting perhaps nearly half a minute; and then, 
the shock, like the sliding fall of a mass of slates on the roof, but 
much heavier, lasting less than five seconds, the house left vibrating 
afterwards. The sound like that of a heavy waggon driven rapidly 
over a rough granite pavement, or like the rapid approach of a 
hurricane gust; the beginning preceded that of the principal vibra- 
tions by more than 15 seconds; it became gradually louder, the 
shock coming like a great blow when the roaring sound was at its 
highest, and then the sound died away like the vibration of a great 
bell, the end following that of the shock by about 15 seconds. 
The above places are all within the isoseismal of intensity IV. 
Inside this line, the nature of the earthquake, though variable to 
some extent, may be summed up as follows: a tremulous motion, 
accompanied by a rumbling sound, increasing in intensity until the 
principal vibrations and a sudden sound (as of an explosion) were 
perceived simultaneously, followed by a tremor and sound which 
gradually died away. At some places, two vibrations, each accom- 
panied by an explosive sound, were observed, as at Redruth and 
Penryn mentioned above. This was also the case at Breage and 
Perran-ar-Worthal. 
Outside the isoseismal of intensity IV., the sound-phenomena 
became relatively more prominent, the shock being felt either very 
slightly or not at all. At St. Keverne, Mr. E. J. Leverton-Spry 
(who was awakened by the sound) felt no shock, but heard two or 
three sounds like knocks at the front door. With this very interest- 
ing account may be compared the following record from Phillack, 
a place on the opposite side of the epicentrum but several miles 
nearer it. The observer was in the open air, standing, and felt no 
shock, but the sound resembled that of successive discharges of 
cannon, about six in number and of equal intensity, lasting about 
three or four seconds. The significance of these observations will 
be pointed out when discussing the origin of the earthquake. 
Time-relations of the Shock and Sound.—These relations have an 
important bearing on the origin of the shocks, and I endeavoured 
in my inquiries to direct particular attention to them. Unfortunately, 
a large proportion of the observers (about one-third) were awakened 
by the shock, and consequently the initial phenomena were lost to 
them. 
The beginning of the sound is said to have preceded that of the 
shock at Camborne, Cury, Gwennap, Helston, Manaccan, Mullion, 
Nancegollen, Porthleven, Redruth, St. Ives, St. Martin and Bt. 
Stythians; coincided with it at Marazion, Mawgan-in-Meneage and 
Penzance ; and followed it (immediately) at Gwinear. 
The end of the sound is said to have preceded that of the shock . 
at Manaccan; coincided with it at Cury, Lannarth, Marazion, 
Mawgan-in-Meneage and Penzance; and followed it at Gwennap, 
