% Mr, Boner an the yuLt| 



another, etod not four irregularly dispersed within the earth, as 

 some have pretended. 



J, have further to observe in favour of my theory that, as the 

 revoldtioti of the magnetic pole seems intimately connected with 

 the relative situations of the planets, so does its latitude appear 

 to be r^guli^ted by the inclinations of their axes. 



The inclination of the axis of the sun is allowed to be 8° or 

 nearly ^o, which being subtracted from 23° 28', the inclination 

 of the aiis of the earth, leave 15° 28', which is very nearly the 

 distance of the magnetic pole from the pole of the earth, as 

 deduced from the dip and variation of 1812, namely 15° 17' 23'^ 

 And if the latitude of the magnetic pole be supposed equal to the 

 inclination of the axis of Venus, its distance from the pole of the 

 es^rtl^ will be 15°, and consequently again very near that found 

 by calculation, which, it is well worth observing, is almost a per- 

 fect meati between the two numbers 15° 28' and 15° resulting 

 from th6 inclinations of the axes of the sun, of the earth, and of 

 Veniis, the difference being less than 3-^ minutes. 



The celebrated Euler, suspecting the cause of the variation, 

 like ain the others that have occupied themselves about this 

 subject, to be within the earth, fixed the north magnetic pole in 

 longitude 96° west of Teneriffe, which being reduced to the me- 

 ridian of ^London brings it to 112° 23', which is the very point 

 where it must have been then, in case its whole revolution be 

 equal to the period, formed of the lunar and solar cycles. 



When we reflect upon this perfect conformity with the revo- 

 lution of the planets, we can hardly entertain a doubt concern- 

 ing their ruling power over the magnet. We acknowledge their 

 power over the waters of the sea, not because we see them 

 really at work, but because time, place, and degree of elevation, 

 are always in perfect harmony with their respective situations. 

 From them we have learnt to foretel the time of setting in, and 

 the quantity of the tide at any place ; and from them we n^ay 

 expect to learn the time and place for any particular degree of 

 variation. But it will require yet some labour and reflection 

 before w^ ihall be able to pronounce with certainty upon the 

 extent ,bf their influence. Could we depend on the correctness 

 of fprnier observations, the work would be greatly abridged, but 

 the errbr^ of many are obvious. For exampk, the same year 

 lotfi ii s^id to have been that in which there was no variation 

 at toufclih and at London, which is impossible, if the variation 

 fpUpiys any rule at all, as I have no doubt it does. For X)u,blin 

 beii|g 6^ y 'to the west of London, th^ time when there was no 

 vanat^Wn'peVe ihust have been about nine years before the same 

 could be observed in London. Again I find tliat there was no 

 variation at' Paris in 1666 ; that is, nine years later than in Lon- 

 d6i^;^fetitParis being 2"^ 20' east of London ought to have expe- 



