[ ' 
But the mod probable way of folving the llafticity 
of Springs, is to corjrider both a repulfive and an 
at^adive Property in the Particles, after the manner 
of the black Sand, which is attraded by the Load- 
done, and has been Ihewn by the learned and inge- 
nious^ Profeflbr Petrus van Mufchenbrook^ to be no- 
thing elfe but a great Number of little Loadftones. 
Fig, 3. Let us fuppofe a Row of round Particles 
touching one another only in the Points c in a Line 
from A to B. It is plain, from what Philofophers 
have fhewn, concerning the Attradion of Cohefion, 
that upon the lead Shake, or Alteration of the Pofi- 
tion of a ftrait Line, thefe Particles will run to- 
gether, and form a Sphere, in which the Globules 
will have more Points of Contad. But if thefe Par- 
ticles have Poles like Magnets in the oppofite Places 
mark’d w, j, fo that all the Poles &c. repel 
one another 5 and all the Poles j, j, x, &c. do like- 
wife repel one another, the Line AB will continue 
ftrait 5 for if by any Force the faid Line B A ht 
put into another Pofition, as into the Curve then 
the Poles &c. being brought nearer together, 
(while the Poles &c. are farther afunder) will 
repel one another more ftrongly, and thereby hinder 
the Globules from running together towards the con- 
cave Part 5 and the Spring, left toitfelf, (all this while 
fuppofing one End, as bj By or /9, fix’d) will reftore itfelf, 
throwing its End a back to Aj and fo on to a, by the 
firft Law: Then being in thePofition a/ 3 , the Poles 
j, r, &c. are brought nearer together, whole Rcpullion, 
thus increas’d, throws back a to Ay and fo on forward^ 
the Line of Particles performing feveral VibratioiiS 
round B* 
May 
