1915-16.] The Ochil Earthquakes of the Years 1900-1914. 259 
(4) 1900, September 22, 4.30 p.m. 
Intensity, 4 ; centre of isoseismal 4 in lat. 56° lO'^ N., long. 3° 50H W. : 
number of records, 20, from 13 places, and 17 negative records from 15 
places (fig. 1). 
The boundary of the disturbed area is an isoseismal line of intensity 
slightly less than 4. It is 11 miles long, 7 miles wide, and 60 square miles 
in area. The longer axis is directed E. 13° N., and the centre of the area 
is If miles N. 17° E. of Menstrie. 
The shock consisted of a single prominent vibration followed by a 
tremor. The sound was heard by 87 per cent, of the observers. 
Slight shocks were also felt on September 18, at 2 a.m., at Alva, and at 
about 2.55 a.m. at Bridge of Allan, but, so far as known, by only one 
observer in each case. 
(5) 1903, May 15, 6.15 p.m. 
A distinct shock, felt generally at Menstrie. 
(6) 1905, April 23, 12.15 a.m. 
A distinct shock, felt at Bed Carr (Blairlogie). 
(7) 1905, July 23, 12.15 a.m. 
Intensity, 5 ; centre of isoseismal 4 in lat. 56° 1T*3 N., long. 3° 47 /, 6 W. ; 
number of records, 33, from 16 places, and 4 negative records from 4 
places (fig. 2). 
The boundary of the disturbed area is an isoseismal line of intensity 4. 
It is 16|- miles long, 10J miles wide, and 136 square miles in area. Its centre 
is 3J miles N.E. of Menstrie, and the direction of its longer axis E. 27 c N. 
On the same map, the portion of the isoseismal 5 lying on the south side of 
the Ochil Hills is shown. Its distance from the isoseismal 4 is 1J miles. 
Within the isoseismal 5, the shock consisted of one or more prominent 
vibrations followed by a series of tremors. Its mean duration was three 
seconds. The sound-area coincided with the disturbed area in all directions 
except perhaps towards the east. The sound was heard by 89 per cent, of 
the observers, 17 per cent, of whom compared it to passing waggons, 10 
to thunder, 27 to wind, 40 to the fall of a heavy body, 3 to explosions, 
and 3 to miscellaneous sounds. 
(8) 1905, July 26, 6.3 p.m. 
Intensity, 4 ; number of records, 9, from 7 places. 
The only records of this shock come from places in the Hillsfoot 
