(So) 
proceeds not from any common Caufc of mo^ 
tion in the Ambient fuidy but is vurted in 
every Chryjlal% fo that it defends indeed 
from the motion of the fubtil Jluidt which 
flows out of the already form'd Chrylfah 
Whereby it CQmes to pafs, 
1. That in the fame place the Chry- 
ftallin matter is joyned to Planes refped^ 
ing the Horizon with a different fcivc. 
2 . That in one and the fame Fluid 
Chryftals are formed of different Fh 
gures. 
Whether the laid Fluid be that,where¬ 
by the Refradion is made, or whether it 
be a Fluid different therefrom, I leave to 
the more Ingenious to difculfe. Cer¬ 
tainly that'thcre is a great efficacy in a 
penetrating Fluid,the length oftheThred^ 
may evincej which arife our of the fil¬ 
ings of Iron about the Poles of a Magnet 5 
not only when thofe filings do. clofely, 
touch the Stone, but alfo thorowinter- 
ppfed, paper 5 vyhere, according as the 
Loadflone is varioufly moved under the 
paper, fo above it, fuch kind of Threds 
do fometimes ouctndoitliQm lying ftill, 
at the other end run through all thofe 
arches that can bqdefcribed within thp. 
