C. Davison — British Earthquakes. 63 



to determine the epoch of tbe shock. I have given it as 6h. 53m., 

 but, as Leith is about 12 miles from the epicentrum, it may have 

 been a few seconds earlier. 



Nature of the Shoclc. — For descriptions of the nature of the shock, 

 I have to rely chiefly on newspaper accounts, and these, as a rule, 

 are far from being either exact or detailed. 



In most parts of the disturbed area, it would seem that the shock 

 was noticed as a single oscillation, the observers in some cases feeling 

 as if the bed or chair on which they rested were slightly raised and 

 then lowered. A few compare the sensation to that of passing over 

 a wave in a small boat. 



From at least five places, however, there come accounts of a 

 second oscillation immediately following the first ; as if there were 

 two prominent vibrations, while the commencing and concluding 

 tremors were generally imperceptible. These places are Edinburgh, 

 Leith, Katho, Balerno, and Peebles. But it should be noted that all 

 observers at these places did not detect the second oscillation ; and 

 this was probably owing to the latter being, as one observer at 

 Edinburgh states, slighter than the first. At Balerno, again, it was 

 remarked that, though both movements were momentary, the second 

 was the more lasting of the two. 



There is only one other noteworthy point that I can gather from 

 the somewhat scanty descriptions. In all the instances, but one, in 

 which the character of the movement is recorded, the oscillation is 

 described as a rise of the ground, followed by a fall. This is the 

 case at Edinburgh, Balerno, Trinity (near Leith), Davidson's Mains, 

 Linlithgow, and Polmont. On the other hand, at Penicuik, a 

 " workman, who happened at the moment to be seated, felt the brick 

 floor recede from his feet, and then, as it were, return to them." 

 Now, the six places just mentioned are in the northern part of the 

 disturbed area ; whilst Penicuik is a short distance to the east of 

 the epicentrum. I shall recur to this point in discussing the origin 

 of the earthquake. 



Duration. — Records of the duration come from seven places, and 

 range from not greater than one second (at Davidson's Mains), to 

 about two seconds (at Edinburgh, Trinity, Leith, and Penicuik), 

 and about three seconds (at Balerno and Kirknewton). Probably 

 some of the estimates of the duration also include that of the sound- 

 phenomena ; but, in either case, they seem to indicate a decrease in 

 duration as the disturbance radiated from the origin. 



Intensity. — The following list gives the intensity of the shock at 

 places where the accounts were sufficiently detailed for its 

 determination. 



VI. Balerno, Currie, Harperrigg. 



Y. Bellsquarry, Corstorphine, Davidson's Mains, Eddlestone, 

 Edinburgh, Gogar, Hartwood, Juniper Green, Kirknewton, Leith, 

 Linlithgow, Penicuik, Eatho. 



IV. or V. Bathgate, Polmont. 



IV. Burntisland, Causewayend, Cockburn, Dumfermline, Eskbank, 

 Peebles. 



