Extract of a letter from a gentleman in Boston, to Benjamin
Franklin, Esq. concerning the crooked direction, and the source of
lightning, and the swiftness of the electric fire. 314
Observations on the subjects of the preceding letter.--Reasons for
supposing the sea to be the grand source of lightning.--Reasons for
doubting this hypothesis.--Improvement in a globe for raising the
electric fire. 320
Effect of lightning on captain Waddel's compass, and the Dutch
church at New York. 324
Proposal of an experiment to measure the time taken up by an
Electric spark, in moving through any given space. 327
Experiments on boiling water, and glass heated by boiling
water.--Doctrine of repulsion in electrised bodies
doubted.--Electricity of the atmosphere at different
heights.--Electrical horse-race.--Electrical thermometer.--In
what cases the electrical fire produces heat.--Wire lengthened by
electricity.--Good effect of a rod on the house of Mr. West, of
Philadelphia. 331
Answer to some of the foregoing subjects.--How long the Leyden
bottle may be kept charged.--Heated glass rendered permeable by the
electric fluid.--Electrical attraction and repulsion.--Reply to
other subjects in the preceding paper.--Numerous ways of kindling
fire.--Explosion of water.--Knobs and points. 343
Accounts from Carolina (mentioned in the foregoing letter) of the
effects of lightning on two of the rods commonly affixed to houses
there, for securing them against lightning. 361
Mr. William Maine's account of the effects of the lightning on his
rod, dated at Indian Land, in South Carolina, Aug. 28, 1760. 362