SBISMOLOGICAL REPORTS. 



43 



Monthly Record of Earth Tremors. 



January 



February 



March 



April 



May 



June 



Tou will thus observe that, during the period under review, more 

 than 70 per cent, of the disturbances are only thickenings of the light 

 line. 



Complete detailed measurements of all the records are appended 

 hereto. 



M.-iGNETU'.VL. 



Although a magnetometer has been established at our branch 

 observatoiy, Red Hill, Pennant Hills, under the charge of Mr. J. W. 

 Short, for several years, owing to certain defects in the instrument, 

 no systematic observations were taken till late in 1907, when a new 

 collimator magnet was received from the National Physical Obser- 

 vatory, Kew, London, and placed in position. 



I foi-ward you the results for February to November, 1908, those 

 being the only observations on which any reliance can be placed. 



I have, &C.J 

 Wm. E. Raymond, Officer in Charge. 

 The Government Astronomer, Observatory, Melbourne. 



EARTHQUAKE RECORDS BY MILNE SEISMOGRAPH. 



As earlv as possiWe after -iOtli Jiiue and 31st December ot each year, the Recorder is reqw&sted 

 to fill up tiie sheets, and post the same to the Secretary of the Karthquake Committee, Britist 

 Association, Burlington House. London, Kiisland. 



These should be accompanied by copies of important .seismogr.ims. Remarks exceeding six 

 words should be entered on separate sheets. 



At the end of each Re.stister the eiiuivalent of 1 nun. of amplitude should be stated in seconds 

 of arc. 



P.T. = Preliminary Tremors. L.W, = Lar,i;e Waves. Time is Greenwich Civil Mean Time ; it is 

 to be given in hours, minutes, and decimals ot minutes : or 21 H = midnight. 



Register from Sydney Ob.servatory— W. Graham, Ob.server. 



Date. 



P.T, Com- 

 mence. 



L.W. Oom- 

 metice. 



Max. 

 Amplitude. 



Remarks. 



1 Januarv. 

 1 ,, ' 



;{ Februai'v 

 3 „ ",, 



16 



27 „ .. 



29 March 



:n 



31 



1-5 

 1-25 

 6-7 

 5 So 



Thickening of line on 8th January from 5 41'8 to 55'8. 



1-5 



0-5 



7-2 



1-85 



(f.55 



11 



0-5 



1-0 



Machine under repjiirs from 23 30 on 2nd April to ti on 3rd .April. 

 Thickening of line on 10th \\m\ from 17 i to is lti-5. 



