(530 
the laft year * I found no more but lo minutes * This Letter ms 
on the fame Meridian. Upon which having 
written this prefenc 
lately applied, fince the receipt of theLetter^ ^^^^* 
the fame two Needles, me thinks, the Declimtion is yetleCsj 
than the laft year. But this I can affiire you, that the T^eclinA- 
tion is yet fome minutes towards the vp, . cu j \u-^ 
^ , n « ' o 1 By the favour of the ^//flrfs 
^d/fj at leaft at Parts, So that you it is not condufive, that becaufe 
may, upon my word, doubt ^ of the ^^'^ D.^clination isjet fomewhat 
r • r r • J ! towards the f a(t at Farffi that 
Obfervation of your fnend, whom per- therefore it mtuUe fo at un- 
haps the Meridian-, or the Needle, or the ^on since 'tis known here, that 
Conftruaionand Divifion of his Com- XfL^lhllrfS^^?! 
pals may have deceived, to a degree and which two pLcesare but 4- E«g- 
a half North' weft, which he at the pre- i'J^' "^^'^s, or thereabout, diftant 
r rr A I -n ^ r irom one another. 
lent amgnes to the Decimation. But 1 
doubt not^ but in 12 or 15 years it will be found true what he 
affirms, as I have prognofticated by my Hj/^^^^//^, which ma- 
teth the Declination to vary a degree every feven or eigk 
years. 
This is, what I had to return to the Letter, which I wifli 
might deferve to be prefented to your Illuflrious Society, and 
-contribute fomething to the difcovery of fo many admirable 
vertues lodgedin this Stone, and principally to the finding out 
of theCaufe of this Variation for which I have already made 
fome attempt, and propofed my thoughts in a Differtati&n de 
Xatitudine Farefienft (^ Magnetis Declinatione, whichM, dt^ Ha- 
mel caufed to be printed Anno 1660, with his A(lronomiaFhy-- 
fica. I (liall be very glad, to learn the fentiment of your Learn- 
ed Philofophers thereupon, and what caufe they fufpedl there 
is of fo Angular an effed, 1 could difcourfe to you of other par- 
ticulars touching the Proprieties of the Load- (lone, and efpecial- 
ly of a remarkable one^ I havedifcover'd, and which, if I am 
mt deceived, fubverts that Theory^ which undertakes to expli- 
cate all thefe effefts by th^ Pmicula (hiata-^ but I refervethat 
for another occaiGon, 
