discoveries of his friend Franklin, and shows the unreasonableness of attributing the earthquake to the action of the rods. He concludes with the hope that he has "fully vindicated the character of those innocent and injured iron points." Some years after, in 1770, he seized another opportunity to defend Franklin's invention, by publishing an essay against the notion that there was great impiety in using lightning-rods, since they prevented the "tokens of Divine displeasure" from "doing their full execution." Under date of October 26, 1770, he writes to Franklin, who was then in London, acknowledging the execution of several commissions concerning books and instruments, and says in regard to the rods: "I have on all occasions encouraged them in this country, and have the satisfaction to find that it has not been without effect. A little piece I inserted in our newspapers last summer induced the people of Waltham (a town a few miles from hence) to fix rods upon their steeple, which had just before been much shattered and set on fire by lightning."
Prof. Winthrop had a clearer understanding of earthquake movements than the generality of scientific men of his time, and was one of the earliest^ if not the first, to apply computation to these phenomena. The chimney of his house was thirty-two feet high, and, observing that bricks were thrown from it so that they fell thirty feet from its foot, he calculated the speed of their motion and found it to be twenty-one feet a second. He perceived also the resemblance between the vibrations of the earth and those of the strings of a musical instrument.
The fullest published account of the scientific work of Prof. Winthrop is contained in the chapter on Boston and Science, contributed to the Memorial History of Boston by Prof. Joseph Lovering, who for over fifty years has occupied the same professorship that Winthrop held. "Prof. Winthrop was fortunate," says Prof. Lovering, "in living at a time when he could be a witness of three celestial occurrences of transcendent importance to the progress of astronomy—namely, the first predicted return of Halley's comet in 1759, after an absence of twenty-seven years, and the transits of Venus across the sun in 1761 and 1769. In 1759 the accuracy of astronomical prediction was on its trial, and, months before the time of the expected visit, astronomers were at their posts and looking; but they were all anticipated by a Saxon peasant who first saw the comet on December 25, 1758. Winthrop saw it on April 3, 1759." He delivered two lectures on comets at this time, which were printed the same year, and reprinted in 1811. Prof. Winthrop also observed the comets of 1769 and of 1770, "one remarkable for its brilliancy and the other for the dis-
- Massachusetts Historical Society's Proceedings, vol. xv, p. 13.