Chap. V. CLAVERING AND SABINE. 143 



ous and not a less important task. The geographi- 

 cal determination of the direction and intensity of 

 the magnetic forces at different points of the earth's 

 surface has been regarded as an object worthy of 

 especial research. To examine, in different parts 

 of the globe, the declination, inclination, and inten- 

 sity of the magnetic force, and their periodical and 

 secular variations, and mutual relations and depen- 

 dencies, could only be duly investigated in fixed 

 magnetical observatories. On the continent some 

 such observatories were established, to which, in the 

 year 1836, the attention of British philosophers was 

 specifically drawn by a letter from the Baron Von 

 Humboldt to the Duke of Sussex, then President 

 of the Royal Society. In consequence thereof ob- 

 servatories for this special purpose were established 

 at Greenwich, Dublin, Canada, Hobart Town, St. 

 Helena, Cape of Good Hope, and other places. 

 The observations made at Toronto have been re- 

 ceived, examined, and printed, under the superin- 

 tendence of Lieutenant-Colonel Sabine— a work of 

 extraordinary care and labour.* He has undertaken 

 besides to examine and arrange the rest as they 

 come in ; which it is expected will be in the course 

 of the present year, 1845. The volume now printed 

 is introduced by an able and well- written preface 

 by Colonel Sabine. 



* See note in Introduction, p. 15. 



