APPENDIX C CXLIII 



the old pattern now in use, it having been shown by Dr. Milne that, with 

 the newer type of instrument, minute preliminary tremors are recorded 

 Avhich, wdth the more slowly moving surface, are frequently lost by hala- 

 tion. The seismographs in use by the Meteorological Service are of the 

 type approved and adopted by the B.A.A.S. Committee for seismology. 



Terrestrial Magnetism. — The magnetic instruments at the observa- 

 tory at Agincourt, Ontario, have been kept in operation, and the hourly 

 ordinates of declination and horizontal force obtained from the photo- 

 graphic traces have been reduced and tabulated. Weekly absolute deter- 

 minations of the declination and dip of the needle, and fortnightly of the 

 horizontal force, have been made in order to check the base line values 

 and determine any changes occurring from loss of magnetism and other 

 irf^trumental alterations. The magnetic declination has increased in the 

 year by 4.8' from 5° 53'.4 to 5" 58'.3 west. The horizontal component 

 has decreased slightly while the dip has increased by 0.6'. From April to 

 the close of August there were no pronounced magnetic disturbances, but 

 a period of disturbance then set in, and during September the magnets 

 were almost constantly in motion and large magnetic storms were regis- 

 tered on the 11th and 12th, and from the 28th to 30th. From October 

 î-nd through the winter months the magnets at times showed abnormal 

 movements, but the only pronounced disturbances occurred on the last 

 two days of January and from the 26th to 28th of March. Many sur- 

 veyors and other observers have visited the observatory in order to obtain 

 either base station values for their instruments or to obtain instruction 

 in the use of instruments. 



In July last an observer who has been attached to the Central Office 

 staff for some years was assigned for duty as magnetic and meteorological 

 observer on the D. G. S. " Arctic," which has been wintering in high 

 latitudes. His instructions were to build a small observatory ashore and 

 devote as much time as possible to magnetic observations. 



Solar Worh. — Owing to the demolition of the old magnetic observa- 

 tory at Toronto early last spiing, the 6" equatorial telescope was dis- 

 mounted and the daily record of solar disturbance as indicated by sun 

 spots had to be discontinued. The instrument will shortly be again 

 mounted, and a much more systematic and closer study of solar disturb- 

 ance by telescope and spectroscope will be commenced and carried on 

 together with measurements of solar radiation as registered by an 

 Angstrom pyrheliometer. 



Investigation as to the more direct causes leading to variations in the 

 character of corresponding seasons in different years, has led to a con- 

 viction that in order to obtain results the circulation of the atmosphere 



