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Experiment I. 
If we lay a magnetical Body under a Piece of 
Paper or Glafs that is ftrewed over with fteel Filings 
or magnetical Sand, and by ftriking the Table put 
the Filings in Motion, they will readily difpofe 
themfeives in fuch a manner as to reprefent, with 
great Exadnefs, the Courfe of the magnetic Matter- 
Steel rendered magnetical is beft for this Purpofe, 
becaufe it is of a more uniform Texture, than Load- 
ftones, and will on that account exhibit a more regu- 
lar Appearance. By this Experiment the curve Lines 
in which the magnetical Matter returns back to the 
Pole where it firft enter’d are accurately expreffed 
by the Arrangement of the Filings. The largeft 
Curves are fuch as take their Rife from one Polar 
Surface, and are extended to the other s being larger 
in proportion as they arife nearer the Axis or Centre 
of the polar Surface. Thofe Curves which arife 
from the Sides of a magnetical Body are always in- 
terior to thofe which arife from the polar Surface $ 
and are lefs and lefs in proportion to their Diftance 
from the Ends. If any one fhould doubt, whether 
the magnetical Matter, which thus difpofes the Fi- 
lings, is really moving back in a Diredion contrary 
to that with which it paffes through the magnetical 
Body ; let him try it in different Parts with a fmall 
Compafs Needle, and the Fad will appear beyond 
Difpute. 
Exp. II. 
The larger the Diftance is from Pole to Pole in 
different Magnets, the larger will thefe Curves be. 
This 
