To John Pringle
MS not found; reprinted from Benjamin Franklin, Experiments and Observations on Electricity (London, 1769), p. 362.
Craven-street, Jan. 6, 1758.
I return Mr. Mitchell’s paper on the strata of the earth9 with thanks. The reading of it, and perusal of the draft that accompanies it, have reconciled me to those convulsions which all naturalists agree this globe has suffered. Had the different strata of clay, gravel, marble, coals, lime-stone, sand, minerals, &c. continued to lie level, one under the other, as they may be supposed to have done before those convulsions, we should have had the use only of a few of the uppermost of the strata, the others lying too deep and too difficult to be come at; but the shell of the earth being broke, and the fragments thrown into this oblique position, the disjointed ends of a great number of strata of different kinds are brought up to day, and a great variety of useful materials put into our power, which would otherwise have remained eternally concealed from us. So that what has been usually looked upon as a ruin suffered by this part of the universe, was, in reality, only a preparation, or means of rendering the earth more fit for use, more capable of being to mankind a convenient and comfortable habitation. I am, Sir, with great esteem, yours, &c.
9. John Michell (1724–1793), astronomer and geologist, held various appointments at Cambridge, 1749–67, and served as rector at Thornhill, Yorkshire, for the last 26 years of his life. DNB. The paper here mentioned was probably “Conjectures concerning the Cause, and Observations upon the Phaenomena of Earthquakes; particularly of that great Earthquake of the First of November, 1755, which proved so fatal to the City of Lisbon …,” read before the Royal Society, Feb. 28, March 6, 13, 20, and 27, 1760. Phil. Trans., LI, Pt. II (1760), 566–634. John Michell is not to be confused with the Virginian Dr. John Mitchell (above, II, 415 n).