282 Proceedings of the Royal Society of Edinburgh. [Sess. 
(180) 1912, July 29, 9.22 a.m. 
A slight shock, accompanied by a noise like that of a falling body, was 
felt at Alva. 
(181) 1912, September — , about midnight. 
On a day about the middle of the month, a slight tremor was felt at 
Dunblane. 
(182) 1912, October 18, about 4.15 p.m. 
A slight but distinct shock, felt at Dunblane. 
(183) 1912, November 6, 5.15 a.m. 
A slight shock, accompanied by a noise like that of a falling body, felt 
at Alva. 
(184) 1913, August 27, 4.30 a.m. 
A thud, followed by a tremor, and succeeded immediately by a second 
thud and tremor, the whole lasting about four seconds, was felt at Airthrey. 
(185) 1913, October 28, 4.30 a.m. 
A shock (intensity 4), accompanied by a sound like that of a falling 
body, was felt at Alva. 
(186) 1914, December 18, 12.54 a.m. 
A slight shock was felt at Airthrey, Alva, Dunblane, and Menstrie. At 
Airthrey there were two distinct shocks in rapid succession, like two shots 
tired from a cannon in the immediate neighbourhood. 
III. Characteristics of the Ochil Earthquakes. 
The earthquakes felt in the Ochil district from 1900 to 1914 (186 in 
number) may be divided into three classes : — 
(i) The first class contains the three principal earthquakes of 
September 21, 1905; October 20, 1908; and May 3, 1912, which were of 
intensities 6, 7, and 7, and disturbed areas of 1000, about 1000, and at 
least 605 square miles, respectively. 
(ii) The second class contains 10 earthquakes, namely, those of 
September 17 (10.15 p.m.), 1900; July 23 and 26, 1905; October 8 (7.24 
a.m.), December 28 and 30 (4.15 p.m.), 1906; October 20 (4.13 p.m.), 1908; 
January 28 (4 a.m.), February 9 (1.32 p.m.), and May 4 (12.10 a.m.), 1912. 
One of these earthquakes was of intensity 3, 3 of intensity 4, 4 of intensity 
5, and 2 of intensity 6. The disturbed area ranges from 74 to 136 square 
miles, the average for all the earthquakes being about 94 square miles. 
(iii) The third class contains the remaining 173 earthquakes. In 24 
of these, it is doubtful whether any tremor was felt. Of the remainder, 
