THE EARTH BENEATH IN THE LIGHT OF MODERN 

 SEISMOLOGY ^ 



By Ernest A. Hodgson 

 Dominion Ohscrvatory, Ottawa, Canada 



The earth is an object of special interest to all of us. . We are, 

 indeed, attracted to it much more strongly than to any other of the 

 heavenl}^ bodies, of which, we must remember, it is one. For the 

 votaries of Urania to turn from their contemplation of the heavens 

 above to a consideration of the earth beneath is in no sense to depart 

 from their allegiance to the Muse of Astronomy. We need not seek 

 to justify the propriety of presenting an address on seismology 

 before an audience of the Royal Astronomical Society of Canada. 



A variety of circumstances make this place peculiarly appropriate 

 for such a subject. We are met under the auspices of a society which 

 has published more articles on seismology than any other in this 

 country. We enjoy the hospitality of a university whose former 

 president — Dr. J. W. (later Sir William) Dawson — made the first 

 statistical studies of Canadian earthquakes.- The lecture room is 

 one of those assigned to the department of physics, one of whose 

 early professors — Doctor Smallwood — operated, as long ago as 1870, 

 what was presumably the first seismograph to be set up on this 

 continent.^ 



We are gathered on the flank of an extinct volcano, but on a rock 

 foundation so solid that we should be comparatively safe in any sort 

 of earthquake we may reasonably expect to experience in Canada. 

 Yet within a mile of this place we can find conditions of unstable 

 soil, coupled with old or shoddy workmanship which would cer- 

 tainly be dangerous were we to experience now an earthquake as 



1 Presented before the Royal Astronomical Society of Canada, Montreal Center, on 

 Thursday, Oct. 31, 1929. Kcprinted by peniiissioti from the Journal of the Royal Astro- 

 nomical Society of Canada, February, 19:!0. 



= Four papers by Dr. J. W. Dawson, which appeared in the Canadian Nat. and Geol., as 

 follows : 



(i) Old ser.. No. 1, pp. 189-196, May 1, 1856. 



(ii) Old ser.. No. 5, pp. 303-P.72, Oct. 17, 1860. 



(ill) New ser., No. 1, pp. 156-159, Apr. 20, 1864. 



(iv) New ser.. No. 7, pp. 282-289, Oct. 20, 1870. 



* Last three lines of the paper by Doctor Dawson, last mentioned in footnote 2, above. 



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