159 



nard observations, corresponds exactly with the epoch of 

 minimum magnetic disturbance, as determined by General 

 Sabine from the magnetical observations made at the colonial 

 observatories and at Pekin ; and he shoves that there is some 

 probability that the period of the change in the rate of 

 decrease also corresponds with the period of magnetic dis- 

 turbance. 



In concluding, the Author tenders his grateful acknow- 

 ledgements to Mr. Vernon^ F.E.A.S., for the valuable assist- 

 ance he has rendered him in procuring data, and in referring 

 to original publications for the purpose of clearing up doubtful 

 points; and he also remarks that without the means of 

 reference afforded by the many valuable volumes of meteoro- 

 logical observations now in the Society's library, it would 

 have been quite impossible to have undertaken an inquiry of 

 this nature. 



