Wilson’s attack on Franklin in 1773, in Observations upon Lightning, had produced a rebuttal from William Henly before the Royal Society. Wilson counterattacked and, when the Society declined to publish his paper, printed it as a second pamphlet, Further Observations upon Lightning; Together with Some Experiments … (London, 1774).3 He sent Franklin a presentation copy, dated on the title page May 25, 1774.4 Franklin read it with the same care that he had given its predecessor, marking passages and adding a few marginal notes. Wilson argued at one point that the electrical fluid behaved differently in two different kinds of conductors and might, when moving through the air as lightning, behave still differently. “Similar,” Franklin replied, “bec[ause] both depend on Quantity” (p. 11). Soon afterward Wilson argued that the quantity of charge in a cloud would determine the distance from the earth that a lightning stroke would cover. “Striking Distance is relative,” Franklin commented. “No one ever pretended it to be a certain Measure” (p. 13). A thunderstorm may last for hours. Wilson continued, and occasion a multitude of explosions that move toward the horizon without diminishing; these were, Franklin remarked, “Repetitions of the same Matter exploding” (p. 16). Henly’s experiment that most interested Wilson demonstrated that, when two chain conductors ending respectively in a knob and a point were exposed in the dark to a discharge, the first chain glowed and the other did not; this proved, according to Wilson, that the point received nothing and was no protection. “No time,” Franklin commented, “for the Point to act” (p. 17). Wilson concluded that the electrical fluid was produced differently by a machine and by lightning, and was governed by different laws. Franklin’s final remark at that point (p. 18) may serve as his verdict on the other’s theories: “Not at all.”