258 
Proceedings of the Royal Society of Edinburgh. [Sess. 
(3) 1900, September 17, 10.15 p.m. 
Intensity, 4 ; centre of isoseismal 4 in lat. 56° ll /- 5 N., long. 3° 50^5 W. ; 
number of records, 56, from 26 places, and 13 negative records from 11 
places (fig. 1). 
The boundary of the disturbed area is an isoseismal line of intensity 
slightly less than 4. It is 15 miles long, 9J miles wide, and 117 square 
Fig. 1. — Earthquake of Sept. 17, 1900 : Continuous line. Earthquake of Sept. 22 : 
Broken line. 
miles in area. The longer axis is directed E. 13° N., and the centre of the 
area is 3 miles N. 8° E. of Menstrie. 
All over the disturbed area, the shock consisted of a single prominent 
vibration, followed by a tremor, such as would be caused by a heavy 
weight falling on the floor and making the building shake. The duration of 
the shock was not more than three seconds. The sound was heard by 94 
per cent, of the observers, and was compared to passing waggons, etc., in 
29 per cent, of the records, thunder in 10, wind in 5, the fall of a load of 
stones in 12, the fall of a heavy body in 17, blasting or explosions in 12, 
and miscellaneous sounds in 15 per cent. 
