the Amber, may, as well as the degree of it, contribute to the Attraction. And my particular Obſervations incline me to adde, that the effect may oftentimes be much promoted, by employing both theſe ways ſucceſſively; as I thought I manifeſtly found when I firſt warm'd the Amber at the fire, and preſently after chaf'd it a little upon a piece of cloth. For then a very few rubbings ſeem'd to excite it more than many more would otherwiſe have done: As if the heat of the fire had put the parts into a general, but confus'd, agitation; to which 'twas eaſie for the ſubſequent Attrition (or Reciprocation of Preſſure) to give a convenient modification in a Body whoſe Texture diſpoſes it to become vigorouſly Electrical.
3. Another Obſervation that is made about theſe Bodies, is, That they require Terſion as well as Attrition; and though I doubt whether the Rule be infallible, yet I deny not but that weaker Electricks re-
