PREFACE.

doubtedly In all other Sorts of Attractions.Therefore, before we set ourselves aboutfinding out a Power , Spirit , or Æther , thatshall move Bodies either by Attraction orRepulsion , it is in the first Place necessary tofind out an Agent that shall do both, forsuch a Principle is at present the Desderatumto our further Advances in the Research ofpatural Causes.

It is sometimes surprizing, to observe,how very fond People seem of this subtleÆther ; one accounts for the Cause of Gra-vity thereby, another for Muscular Motion ,a third for Electricity, a fourth from hencederives Animal Spirits , a fifth ElementaryFire: And, in short, we want nothing butthe Proof of such an Æther to account foralmost every Thing by it. But is it not apreposterous Proceeding to account for anyThing by a Principle in itself unaccountable,and utterly unknown ?

However, we are arrived at great Dex-terity since Sir Isaac's Time; for we can nowalmost prove the Existence of this Æther bythe Phænomena of Electricity; and then wefind it very easy to prove that Electricity isnothing but this very Æther condensed andmade to shine. But, I believe, when weenquire into the Nature and Properties ofthis Æther and Electricity, we shall find

them