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To the VIIIth. Chapter.
Observation II.
TO shew that the Suspicion I mention my self, a little be∣fore the end of this Chapter, to have had, that the breaking of the Stones there spoken of might possibly be produc'd or promoted by some im∣pressions, remaining after the strokes employ'd to force the Stones out of their Beds, was not altogether with∣out ground.
I shall here observe, that it need not seem incredible, that faint strokes and attritions may leave more lasting and operative Motions among the Insensible Parts, even of compact and solid Bodies, than one would readily imagine. For I have several times found, sometimes by Observa∣tions designedly made, and some∣times by undesigned Accidents, that, having caus'd somewhat thin Vessels of Glass, especially Urinals, to be di∣ligently