and a fmall white mark, / had made upon this Stofte, remained 
ftiU in the lame place, where / had put it;) without turning at all r 
whence / thought the Propofitioa of Gil&en fufficiently re- 
futed. 
This Sto^2e, having ferv'd me for this Experiment, did, toge- 
ther with the greater SPo^e^ (whereof the Poles wqig alfowell 
marked ) ferve me alfo to find out, whether the Needles, touch- 
ed in different places, nearer to^ or further from the Poles, had 
different Declinations. Which having tryed frequently with 
thefej and with other Stones, /found no difference at all in the 
JDeclimtmoi tb^ Needles. 
And now to return to the main fubjed of the Letter, / then 
obferv'd, that allthefei\r^^^fo declined z^^;; from the Meridian 
4 \ degrees from the North Eaftward. And, as / did not fufpeit^ 
that this declination would have changed, having found it to be 
the fame in many places, from Breff in Brittany to the Falto- 
line among the Alpes^ I believed, tne Antients had illobferv d,. 
and that the want of their exadnefs, in refpedl either of the 
Meridian-line y or the fabrick of their iV^^r^j//^/, or tkedivifionof 
their Circles^ was the caufe of this defed. But / wasfoon un- 
(feceived of my own Error, when / learned a little while after^ 
by Letters from i\i2xy[x. Burrows, Anno 15S0. had 
mzx London obferv'd the declination of the Needle to be 11. 
degr. 1 1 . min. as weU as ofiiCim and Sennertus : And that Anna 
1612, Mr. (7/^;^^A^rjProteuor of theMathematicks, had in the 
fame place found that Z>^r//W/^?;^ much diminiflit, having then 
found but 6 degrees : Andla/lly, that Anno 16^^. Mr. CeUthrand 
had found it but 4. degrees i\r^r^^-^4/, conformable tomyOb- 
fervations. Which did affure me, that thofe Declinations were 
not conftant, but had varied. 
And that / might be convinced by my felf, I made from time 
to time Experiments in divers places, and found ftill more and 
more diminution-, fo that Anno 1660, in ^uney after /had very 
exactly traced a Meridian by many J&imuthsy before and after 
noon, with a Brafs- Quadrant of 6, foot diameter ^ andapplyed 
good Needles upon ir^ theoneofy. the other of 10. /W^^-/ long, 
/ fouad that ihey declined but one degree, or thereabout : And 
