“I wish I had mathematics enough to satisfy myself whether the much shorter voyages made by ships bound hence to England, than by those from England hither, are not in some degree owing to the diurnal motion of the earth, and if so in what degree. It is a notion that has lately entered my mind; I know not if ever any other’s.” (Bigelow’s Works of Franklin, vol. ii. p. 14.)
He referred to the subject again soon after, and finally a few years before his death,[20] but always as an unsettled question. The idea seems never to have got beyond the stage of investigation with him, but Parton has built up out of it a wonderful discovery.
“He conceived an idea still more practically useful, which has since given rise to a little library of nautical works, and conferred unmerited honor upon a naval charlatan—Maury. This idea was that by studying the form and motions of the earth and directing a ship’s course so that it shall partake of the earth’s diurnal motion a voyage may be materially shortened.” (Parton’s “Life of Franklin,” vol. ii. p. 72.)
This is certainly a most extraordinary statement to be made by a writer like Parton, who has given the main facts of Franklin’s life with considerable fidelity. He refers to it again in another passage, in which he says that this method of navigation is now used by all intelligent seamen. But there is no evidence that it was ever so used. He may have confused it with great circle sailing. The theory is an exploded one. There is no library of nautical works on the subject, and I think that the officers of the United States navy, the captains of the great ocean liners, and thousands of sailors all over the world would be very much surprised to hear Maury called a charlatan.
Maury’s wonderful investigations were not in the line of sailing a ship so as to take advantage of the earth’s diurnal motion, and could not have been suggested by such an idea. He explored the physical geography of the sea, and particularly the currents, trade-winds, and zones of calm. It was he who first worked out the shortest routes from place to place, which are still used. Although he never made a picturesque and brilliant discovery about lightning, and had not Franklin’s exquisite power of expression, he was a much more remarkable man of science.
In a long letter to Alphonsus Le Roy, of Paris, written in 1785, on his voyage home from France with Captain Truxton, Franklin summed up all his maritime observations, including what he knew of the Gulf Stream. This letter is full of most curious suggestions for the navigation of ships, and was accompanied by a plate of carefully drawn figures, which has been reproduced in most editions of his works.
So much attention had been given, he said, to shaping the hull of a vessel so as to offer the least resistance to the water, that it was time the sails were shaped so as to offer the least resistance to the air. He proposed to do this by making the sails smaller and increasing their number, and contrived a most curious rig (Fig. 4) which he thought would offer the least resistance both in sailing free and in beating to windward.
FRANKLIN’S MARITIME SUGGESTIONS