Philadelphia, July 16, 1747
. . . . . . . . . . .
I THANK you for the curious facts you have communicated to me relating to springs. I think with you, that most springs arise from rains, dews, or ponds, on higher grounds; yet possibly some, that break out near the tops of high hollow mountains, may proceed from the abyss, or from water in the caverns of the earth, rarefied by its internal heat, and raised in vapour, till the cold region near the tops of such mountains condenses the vapour into water again, which comes forth in springs, and runs down on the outside of the mountains, as it ascended on the inside. There it is said to be a large spring near the top of Teneriffe; and that mountain was formerly a volcano, consequently hollow within. Such springs, if such there be, may properly be called springs of distill'd water.
Now I mention mountains, it occurs to tell you, that the great Apalachian mountains, which run from York River back of these colonies, to the Bay of Mexico, show in many places, near the highest parts of them, strata of sea shells; in some places the marks of them are in the solid rocks. It is certainly the Wreck