( 204 ) 
IX. BxtraSi of a Letter from Dr. Brook Taylor, 
F, -R. S. to Sir Hans Sloan, dated ‘ i 5. June, 
1714* Giving an Account of fome Experiment* 
Fter having given an Account of an Experi- 
ment made with the large Magnet in the Re- 
pofitory of the Royal Society , ("which Experiment is 
described in Philofoph. Tranfath No. 344. Article 4.) 
The Letter goes on with the fame Subject as follows., 
— If it were known what point within the Stone, and 
what point in the Needle are the Centers of the 
Magnetical power, it would be eafy to find the true 
powers of the Magnet at all the diftances obferved. 
For want of that Knowledge, I have computed the 
Forces from the Center of the Needle, and the Ex- 
tremity of the Load hone, and find, that at the dif- 
tance of nine Feet, the Power alters fafter, than as 
the Cubes of the diftances, whereas at the diftances 
of one and two Feet, the Power alters nearly as- 
their Squares. To try whether the Law, by which 
the Magnetifm alters, could be reduced at all dif- 
tances to any one certain power of thofe diftances, I 
fought thofe points in the Needle and Stone, which 
being ufed as the Centers of the power, might have 
that property. But in that cafe, I found the Center- 
of the Stone mutt be carried quite out of its Figure, to 
make the diftances large enough for this purpofe.. 
From whence it feems to appear, that the power of 
.1 • 
Magqetifm 
