318 Dr. C. Davison—British Earthquakes. 
the observers.. In 47 per cent. of the records it is compared to 
passing wagons, etc., in 27 per cent. to thunder, in 17 to the fall 
of a heavy body, and in 10 per cent. to explosions. The beginning 
of the sound preceded that of the shock in 33 per cent. of the records, 
coincided with it in 54, and followed it in 13 per cent.; the end of 
the sound preceded that of the shock in 19 per cent. of the records, 
coincided with it in 383, and followed it in 47 per cent.; the duration 
of the sound was greater than that of the shock.in 39 per cent., equal 
to it in 39, and less than it in 22 per cent. 
16. Ochil Harthquake: October 20, 1908, 4.13 p.m. 
Intensity 5; centre of disturbed area in lat. 56° 11:3’ N., long. 
3° 48:0’ W.; number of records 18, from 13 places. 
The boundary of the disturbed area coincides nearly with the 
isoseismal 6 of the preceding earthquake, except that it is displaced 
about half a mile to the west-south-west. The area is 15 miles long, 
101 miles wide, and contains about 128 square miles. Its centre is 
3 miles E. 50° N. of Menstrie and half a mile west-south-west of 
that of the isoseismal 6 of the preceding earthquake, and its longer 
axis is directed E. 25° N. The intensity of the shock was greatest 
(namely, 5) at Tillicoultry. The shock was merely a brief tremor, 
lasting about 14 seconds, without any prominent vibration or ‘thud’. 
The sound, which attracted but little attention, was compared to 
thunder or an explosion. 
17-386. Ochil Earthquakes: October 20, 1908 — October 22, 1909. 
17. October 20, 1908: 9.26 p.m.—A very slight shock felt at 
Airthrey and Menstrie. At Airthrey the sound and vibration began 
together, and terminated simultaneously in a thud. 
18. November 6, 1908: 4.45 p.m.—A noise heard at Menstrie. 
19. January 19, 1909: 5.28 a.m.—A shock, of intensity 4, felt at 
Airthrey, Alva, and Menstrie, accompanied by a loud sound. 
20. January 19, 1909: 5.29 a.m.—A shock, felt at Memstrie. At 
Alva two tremors were felt after the shock at 5.28 a.m., but the times 
are not known. 
21. January 28, 1909: 12.15 p.m.—A slight concussion, of 
intensity 3, felt at Airthrey and Menstrie, accompanied by a noise like 
that of an explosion underground. 
22. January 24, 1909: 12.15 p.m.—A shock, of intensity 3, felt at 
Menstrie. 
23. January 24, 1909: 2.28 p.m.—A tremor felt at Airthrey. 
24. January 24, 1909: 3.35 p.m.—A tremor, of about the same 
intensity as the preceding, felt at Airthrey. 
25. January 27, 1909: 1.40 p.m —A slight shock felt at Menstrie. 
26. February 22, 1909: 7.26 p.m.—A noise heard at Menstrie. 
27. March 19, 1909: 9.35 a.m.—A shock, accompanied by noise, 
felt at Menstrie. 
28. May 22, 1909: 3.23 p.m.—A shock, of intensity 5, felt at 
Airthrey and. Menstrie; accompanied by a sound like that of an 
explosion. 
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