I. Introduction. The earthquakes of Inverness and Comrie, though never so strong as those of Essex and Hereford, bear, in their long trains of aftershocks, a far closer resemblance to the great earthquakes of other countries. Since the Comrie earthquake of October 23rd, 1839, which was followed by 330 tremors and earth-sounds within little more than two years, 1 no British earthquake has been attended by so many accessory shocks as that which occurred in the neighbourhood of Inverness on September 18th, 1901. The unusual intensity of the earthquake, its apparent connection with the great northern boundary-fault of the Highlands, and the possibility of tracing vscillations in successive centres of disturbance along the faultsurface, combined in rendering a detailed investigation desirable. 2 The names of all those who have assisted me are too numerous to :mention here; but, in offering my best thanks to them collectively, I should like to acknowledge my special indebtedness to Mr. W. J. Watson, l~ector of the Royal Academy, Inverness, Mr. A. S. Reid, F.G.S., of Trinity College, Glenalmond, Mr. S. Archibald of Dalarossie, and Miss Isabel Forbes of Teanassie, near Beauly, for the most useful series of accounts which they have kindly collected. Valuable records of after-shocks have also been communicated to ~e by the following gentlemen :—Mr. D. Forsyth (Inverness), Mr. James Fraser (Aldourie), Mr. John E. Fraser (Dores), Mr. P. Fraser (Holm, near Lentran), Mr. A. Grant (Drumälan, near Drumnadrochit), Mr. W. Grant (Invermoriston), Mr. R. Keillar ,(Lochend, Aldourie), Mr. W. Mackenzie