British Association for the Advancement of Science. 225 



opposite to each other, and are always in the polar chcles, which 

 they traverse from W, to E. during a space of 600 years ; — or rather 

 but appear to do so, as the earth during about the same space of 

 time performs a revolution from E. to W. Hence follows that the 

 compass points to rfie true north in the meridian circle all around 

 the earth, on which the moveable pole at that moment is situate* 

 except however the arch between the fixed and moveable poles, 

 where the variation alters according to the different distance from 

 the respective poles. Hence further follovte, that to the east of the 

 meridian of the moveable north pole the variation is west, and to 

 the west of it east ; whereas, of course, the reverse is the case with 

 the meridian of the moveable south pole. Finally, the greatness of 

 the variation depends upon the angle which the moveable pole 

 makes with the meridian of every given place, and this greatness 

 must, if my theory be right, at any time be calculable; for if the 

 moveable poles absolve their course in 600 years, the compass must 

 point to the true north at any place between the polar circles every 

 300 years, whereas within the polar circles this only takes place 

 once during 600 years. Here (namely, within the polar circles), 

 when the compass has pointed to the true north, the variation (E. 

 in the southern, and W. in the northern hemisphere) during 300 

 years ascends to its maximum, and then, the moment the moveable 

 pole crosses the place's meridian, leaps to as great opposite varia- 

 tion, which then in its turn decreases during 300 years until it 

 again points to the true north." 



XXX. Proceedings of Learned Societies. 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



WE are happy to announce that the First Report of this Association, 

 consisting of the Proceedings and Transactions of the Meeting 

 held at Vork in the autumn, and of the Recommendations of the Com- 

 mittees, is printed, and will shortly be published. In the meantime 

 we have permission to give the Preface to the Report, and the Recom- 

 mendations of the Committees. We have also transferred to our 

 pages Dr. Henry's interesting estimate of the scientific character of 

 Priestley, which will be found at p. iJOJ of the present Number: this 

 was the only memoir read to the meeting, which is given entire in 

 the Report. 



Preface. — In giving to the public a Report of the Proceedings of 

 the British Association for the Advancement of Science, it has been 

 considered an important object to add to the account of the past 

 meeting a distinct view of what is to be expected from the next, and 

 to announce the result of the applications which have been made to 

 individuals, requesting them, in the name of the Association, to 

 undf rtuke tiie reports and researches recommended by its commit- 

 tees in different branches of science. 



The success of these applications will appear from the following 

 statement. 



iV..S. Vol. 11. No, 63. March 1832. 2 G Reports. 



