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Franklin also combined science and mechanical practicality by devising the first urinary catheter used in America, which was a modification of a European invention. His brother John in Boston was gravely ill and wrote Franklin of his desire for a flexible tube to help him urinate. Franklin came up with a design, and instead of simply describing it he went to a Philadelphia silversmith and oversaw its construction. The tube was thin enough to be flexible, and Franklin included a wire that could be stuck inside to stiffen it while it was inserted and then be gradually withdrawn as the tube reached the point where it needed to bend. His catheter also had a screw component that allowed it to be inserted by turning, and he made it collapsible so that it would be easier to withdraw. “Experience is necessary for the right using of all new tools or instruments, and that will perhaps suggest some improvements,” Franklin told his brother. The study of nature also continued to interest Franklin. Among his most noteworthy discoveries was that the big East Coast storms known as northeasters, whose winds come from the northeast, actually move in the opposite direction from their winds, traveling up the coast from the south. On the evening of October 21, 1743, Franklin looked forward to observing a lunar eclipse he knew was to occur at 8:30. A violent storm, however, hit Philadelphia and blackened the sky. Over the next few weeks, he read accounts of how the storm caused damage from Virginia to Boston. “But what surprised me,” he later told his friend Jared Eliot, “was to find in the Boston newspapers an account of the observation of that eclipse.” So Franklin wrote his brother in Boston, who confirmed that the storm did not hit until an hour after the eclipse was finished. Further inquiries into the timing of this and other storms up and down the coast led him to “the very singular opinion,” he told Eliot, “that, though the course of the wind is from the northeast to the southwest, yet the course of the storm is from the southwest to the northeast.” He further surmised, correctly, that rising air heated in the south created low-pressure systems that drew winds from the north. More than 150 years later, the great scholar William Morris Davis proclaimed, “With this began the science of weather prediction.”4 Dozens of other scientific phenomena also engaged Franklin’s interest during this period. For example, he exchanged letters with his friend Cadwallader Colden on comets, the circulation of blood, perspiration, inertia, and the earth’s rotation. But it was a parlor-trick show in 1743 that launched him on what would be by far his most celebrated scientific endeavor. ELECTRICITY On a visit to Boston in the summer of 1743, Franklin happened to be entertained one evening by
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