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Refraction equally with that Part we call the Root.
5. Icicles and Dropſtones.
That the Spar formed in Fiſſures of Rocks, is thus waſhed out of the Limeſtone itſelf is certain:
Becauſe none but Limeſtone Rocks have Spar in their Fiſſures; Rocks of Cryſtaline Matter, or formed of vitrifiable Stone, have Cryſtal; never Spar in their Cracks.
Linnæus wonders at the Nature of that Force which ſplit the Rocks into theſe Cracks: But probably the Cauſe is very familiar; they were formed moiſt, and cracked in drying.
Spar grows continually; for whereſoever there is a Crack in a Limeſtone Rock, new, or old; Spar always fills it; and over-runs the Surface.
Letters cut hollow in a living Rock of Limeſtone, fill up, in a Courſe of Years, with Spar; and what were made in Creux are found in Relief. This has been ſeen in Gothland by the eminent Swede; and in the Grotto of Antiparos by Tournefort. The very Time may be determined by the Dates, which are often a Part of the Inſcription; but it is always long. The Spar ſtands higher as the Time is more diſtant: and has been feen in ſome Places a Quarter of an Inch above the Level of the Surface.
If there could want a Proof of the continual Growth of Spar, the Stalactites would ſhew it; and the Incruſtations, in what are called our
