ctm 
liaa its rife, and whence alfo the Principal Gbfervatlons of 
the Change of its Declination are come to us*, fo that ’tis juft 
that the Obfervations > made elfewhere concerning the fame, 
ihould return thither , as to its fouree. 
I fhall therefore let you know, that having alwayes been 
Curious in the Dodrine of the L oad- Stonej after I had made 
the Experiments, that are in Gilbertus and others, / made 
that of the Needles Decimation on three different Meridian- 
Lines, which I traced An. 1630. in feveral places of Faris^ 
and found , that the Needle declined 4' degri North eafh: 
which having publiflu , and made known here to the Curious 
and to Artifts™, fome of whom counted 9 or 10 degrees accor- 
ding to the Tradition and Writings of Orontius Fineus , and 
Caftelfranc *, others, 1 iy degrees, following Sennertus and of 
frfws,: all at Erft .rejeded my Obfervation^ and as common- 
ly New things meet with obftacles and contradidions , before 
they are eftabliiht,thofe that could not contradid what they fa w ? 
pretended, that this Variety did perhaps proceed from the 
greater or leffer vigour in the Loadftones, employed to touch 
with? or from thence, that the Needles had been touc If t near- 
er to or farther from their Poles -? which might make them - 
decline more or lefs from the Meridian, fo as. , a Needle, be- 
ing precifely toucht by the Pole of a good Magnet, might 
perhaps have no Declination at alf 
All which conjedures were not without their 'probabili- 
ty*, which- was the greater , in regard that all the Load- 
fiones I had feery being rude and like Flints , with irregu- 
lar furfaces, in bunches and cavities, their Foies were _ al- 
wayes ill pofited, and often within fome of the Cavities, 
fo that one could not be fure to ftrike the Needle tho- 
row the Foie of the Stone, To- remove which difficulty 3 
and at the fame time to find another quality fone of the ex- 
cellenteft of- the World, if true *, ) viz, that which Gilbert 
bad afligned to T errellas 5. Jrefpiv’d ., to make the Experi- 
ment of it. And becaufe / have hot yet written of at, nor any 
man, I know., ( Men having, contented themfeives with re- 
futing this Error by Difcourfe only ) you will perhaps not be 
• clrfoledhd to' be, inform'd- of. the fuccefs thereof, 
— ■' — - • “* “ 
