Copy letter from Joannes Alphonsus Borellus to Henry Oldenburg ' Signor Borelli's Letter signifying his making a present to the Royal Society of his description of the fire of Mount Aetna [Etna] and of his treatise de montionibus a Gravitate pendentibus ' Note at beginning of this letter; ' Here follow a couple of Letters iinsderted here though out of their place, because they had been mislaid, and were not lighted on, till others, anterior to them in date, had been entered. ' 10 April 1671