110 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



parallel to the length of the boom. The position of this, beneath a slit at right 

 angles to it, is shown by a speck of light from a small lamp, reflected down, which 

 photographs continuously on a bromide film two inches wide, which passes at the 

 rate of five -feet each day. Every hour the light is eclipsed by a screen attached to 

 the long hand of a watch, and thus a time scale is supplied. 



After the departure of the members of the British Association we lost no time 

 m getting the instrument in position, but unfortunately were unable to begin 

 operations immediately, as the maker had failed to send us the necessary paper, and 

 it was not until the 20th September that the clock was set in motion. I say unfortu- 

 nately, because there was great disturbance on at the very instant the record began, 

 and we have a clear record of the maximum and last vibrations caused by an earth- 

 quake which Professor Milne informs us occurred in Borneo. 



There are difficulties to contend with in the management of the seismograph, 

 and the greatest of all is vibration df the pendulum, caused, we believe, by some 

 movement of the air. Professor Milne has been unable to altogether get rid of 

 the movement in his instrument in the Isle of Wight; he is inclined to think it is 

 caused by air currents. He has studied the vibrations under various atmospheric 

 conditions, and apparently finds, as we do, that the disturbance is most pronounced 

 on clear, calm nights when radiation is great. It is a subject for investigation, 

 whether we are not registering on our seismograph the very atmospheric tremors 

 or waves which cause telegraph wires to hum on clear, calm nights, and that, Mr. 

 Percival Lowell asserts, are the cause of bad seeing on certain nights which, to all 

 appearance, ought to be good for astronomical observations. 



Since the starting of the instrument we have recorded eleven very decided 

 quakes and nine small earth tremors; many others have perhaps been lost in the 

 air current disturbances. The most marked of the eleven was the first one, the origin 

 of which Professor Milne places in Borneo; the next in order of importance occurred 

 on December iQtli, when earthquakes were reported both from Bermuda and Italy, 

 this was not recorded in Great Britain. Next came one on December 28th, and was 

 followed by a larger one on the 29th; and both were also recorded by Milne in the 

 Isle of Wight. 



The preliminary tremors on the 28th (Fig. i) began at Toronto at 8h. 24m. 37s., 

 Greenwich mean time, and in the Isle of Wight at 8h. S4m. 51s., or over half an 

 hour later. At present we have no knowledge of the origin of this distui^bancc; The 

 disturbance of the 29th at Toronto (Fig. 2) was marked by the absence of pre- 

 liminary tremors, and vibrations of large amplitude began at iih. 32m. 29s. In 

 the Isle of Wight preliminary tremors began at iih. 40m. 48s., and the larger waves 

 at I2h. cm. 37s., or 28m. 8s. later than Toronto. The origin of this disturbance was 

 obviously near the north coast of San Domingo. Two cables were broken by it, 

 and, according to newspaper reports, the town of Santiago was greatly damaged at 

 about iih. 29m.; which time, however. Professor Milne thinks is an error, and is 

 inclined to place six minutes earlier. The distance from San Domingo to Toronto is 

 1,510 nautical miles, and to the Isle of Wight 3,823 miles. We are endeavouring to 

 obtain further particulars from San Domingo regarding the time of the shake, and if 

 successful the comparison will be particularly interesting. The last important shock 

 was on January 24th, the preliminary tremors beginning in Toronto (Fig. 3) at 

 I2h. i8m. 28s., or 32m. 39s. later than in England ; this would seem to indicate a 

 very dififerent origin from those of December, perhaps in Asia Minor. At the 

 Toronto meeting of the British Association last year Professor Milne obtained a 

 grant for the construction of a few seismographs, and I promised to place one of 

 them in charge of the meteorological observer at Victoria, B.C. The instrument is 

 nearly ready for shipment, and will probably be placed in position about the ist of 

 June. This will be another link in the chain of seismological stations, and it is 

 pleasant to know that Canada is taking a very active part in this most interesting 

 and important seismic survey. 



