The discourse made before the Royal Society the 26. of November, 1674, concerning the use of duplicate proportion in sundry important particulars together with a new hypothesis of springing or elastique motions / by Sir William Petty, Kt. ...

An Appendix OF ELASTICITY.

HAving done with the Consideration of du∣plicate and subduplicate Proportion in Elastic Bo∣dies and Materials, I hope it will not be amiss to sub∣joyn a short Appendix of Elasticity it self, whereby to draw forth the better

thoughts of other men for Countenance or Correcti∣on. Wherefore I say as followeth; viz.

• First, Supposing every Body to have a Figure or Positure of its own, out of which it may be disturbed by External Force; I say, that Elasticity is the power of recovering that Figure, upon removal of such Force.
• 2. I think it easiest to consider Elastic, Springing, or Resilient Bodies, as La∣minae,

• ... Laths, or Lines; so as a streight Lath, being by force bent circularly, doth upon the removal of that Force, return to be streight again by its Elasti∣city; and a Circular Hoop being forced streight, leaps back into its own crooked∣ness by its Elasticity.
• 3. Elastic Bodies in their returns do overshoot their own Natural Positure, and vibrate cis citrà the Point they seek, as doth a Pendulum, or Magnetic∣Needle,

• till at length they rest; the one in his Per∣pendicular, and the other in his Meridian.
• 4. An Elastic Body is a gross Tangible Body, which is made of Corpuscles, or the smallest Bodies that can possibly be seen; and these Corpuscles are made of A∣toms, or the smallest bodies in Nature (such as whereof a Million doth not perhaps make one of the Corpuscles last mentioned.)
• ...

• 5. I know no reason, why we may not, upon oc∣casion, suppose Atoms to be of several Figures and Magnitudes, provided we suppose them immutable, such as Corpuscles are not; gross tangible Bodies be∣ing very mutable by the various Additions and De∣tritions that befal them.
• 6. I suppose in every A∣tome three such points as we all see and know to be in the Globe of the Earth, and in every Magnet, viz. two

• ... Poles in its Superficies, and a Central point within its substance, which I call its Byas. The Heavens also visibly have their Poles, and must have a Center of Gravity or Magnitude, or some other Central and pre∣dominant Point.
• 7. I suppose every A∣tome may move about his own Axis, and about other Atoms also, as the Moon does about the Earth; Ve∣nus and Mercury about the Sun; and the Satellites

• ... Iovis about Iupiter, &c.
• 8. I suppose, that the Byas of one Atome may have a tendency towards the Byas of another near it, and that the Byasses of many Atoms may tend to some common point with∣out them; as we see in Electrical Bodies, and in the Globular drops of Wa∣ter and Quicksilver, and all Mucilaginous Substan∣ces.
• 9. I suppose, that all A∣toms have, like a Magnet,

• ... two Motions, one of Gravity, whereby it tendeth to∣wards the Center of the Earth, and the other of Verticity, by which it tend∣eth towards the Earths-Poles, and whereby Mag∣nets joyn to each other by their Opposite Poles.
• 10. All Atoms by their Motion of Verticity or Po∣larity, would draw them∣selves, like Magnets, into a streight Line, by setting all their Axes in directum to each other; did not the

• Motion of their respective Byasses towards each other, and towards other Points, curb them into a Triangle, whereof the Two Axes of Two Atoms are two sides, and the distance between the Byass of each making the third side: Wherefore I call the Polar Motion a∣bove-mentioned, the Mo∣tion of Rectitude; and the Motion of the Biasses, the Motion of Angularity or Curvity, or the Angular or Curve Motion.
• ...

• 11. I suppose, that all these Motions may be of different Velocities, and that by Contra-colluctations they ballance each other, some∣time into seeming rest: I say, seeming, because per∣haps there is no rest in Na∣ture.
• Lastly, I might suppose (even without a Metaphor) that Atoms are also Male and Female, and the Active and Susceptive Principles of all things; and that the above-named Byasses are

• the Points of Coition: For, that Male and Female ex∣tend further than to Ani∣mals, is plain enough; the fall of Acorns into the ground, being the Coition of Oaks with the Earth. Nor is it absurd to think, that the words in Genesis, [Male and Female crea∣ted he them] may begin to take effect, even in the smallest parts of the first Matter. For although the words were spoken onely of Man; yet we see they

• certainly refer to other A∣nimals, and to Vegetables in manner aforesaid, and consequently not impro∣bably to all other Principles of Generation.