166 MAGNETISM. 



If 9 A.M. be our standard, the readings are 



A.M. P.M. 



48 9 4 9 10 



0103 -0015 Standard. '0178 '0008 '0016 



I regret that much absence from Yorkshire of late years has 

 prevented me from yet making observations on this oscillation of 

 the barometer at a height of 1200 feet above the sea, an expe- 

 riment which promises very curious results. 



CHAPTER VI. 

 MAGNETISM. 



UNDER this head I shall merely state some of the angular mea- 

 sures and numerical values of the magnetic elements in York- 

 shire. The direction taken by an iron bar or wire free to move 

 under the influence of the earth's magnetism at York, is in a 

 vertical plane intersecting the plane of the meridian, at an angle 

 of 24 to the west of north, and inclined downwards from the 

 horizon 70^. The angle of deviation to the west has grown up 

 to its present value of 24 in the course of 200 years*, and now 

 appears to be slowly diminishing ; the angle of inclination from 

 the horizon has been growing less by about 2''3 in the year, for 

 the last thirty years, and probably for a much longer period, and 

 this rate of diminution (subject to much fluctuation however) 

 still continues. 



The line along which the deviation of the needle to the west 

 is the same as at York, is not ascertained. 



* In the middle of the 17th century (1657 according to Cavallo) the 

 needle pointed due north and south. 



