Over at PACHSmörgåsbord, brought to us by the Philadelphia Area Centre for History of Science, Darin Hayton has been catching the longitude vibe while investigating the collection of the Library Company of Philadelphia. He describes an anonymous 1688 pamphlet that, famously for those who have looked into the history of longitude, suggests an intruiging solution to the problem.The full title of the pamphlet is Curious Enquiries. Being Six Brief Discourses viz I. Of the Longitude. II. The Tricks of Astrological Quacks. III. Of the Depth of the Sea. IV. Of Tobacco V. Of Europes being Too full of People. VI. The various Opinions concerning the Time of Keeping the Sabbath. As Darin shows, this pamphlet is "an amusing satire of scientific or purportedly scientific practices" and the first section reviews many "whimseys" about finding longitude before suggesting what the author claims is a properly workable idea.This refers to the idea of a powder of sympathy that, within the framework of natural magic, was a means of healing wounds at a distance, by applying the powder to the weapon that made the wound, or a bandage that had been used to bind it. This, as the pamphlet explains, was something that had been seriously investigated by Sir Kenelm Digby, Fellow of the Royal Society. (By coincidence he also gets a mention today on the Royal Society's new book reviews feature.) The potential of this salve as a longitude solution was that, according to Digby, when it was applied to the bandage, it instantaneously made the patient start. Why not, the anonymous writer suggested, take a wounded dog to sea and have someone back in London, at an appointed time, dip the bandage in the powder and then the person on board ship, with the yelping dog, would have an accurate knowledge of London time to compare with observations of local time.This 'solution' receives frequent mention in the literature. Owen Gingerich cites it as being "entirely tongue in cheek" in The Quest for Longitude (1996, p. 135). Dava Sobel, whose Longitude was inspired by the conference that led to Quest, also described it, but prefers the reader to take it slightly more seriously (Darin says she "remains agnostic", but I think this is on the generous side). Recently it made an appearance on James May's Man Lab and it is, of course on Wikipedia, although it states that "it is possible that the pamphlet was a form of satire". It also appears in the Time and Longitude Gallery at the Royal Observatory, where, if you open a door in the panelling, you will catch a figure dipping bandages and hear the dog barking. (It is a strange experience going through Flamsteed House out of hours when all is quiet save ticking clocks, a recording of the BBC pips and the occasional yelp.)Part of the reason for the popularity of the story, and the fact that often it is taken as a genuine proposal, is undoubtedly its oddness-factor. They did what? They believed that? However, it is also emblematic of some truths, that can be useful in communicating with the public. On the one hand, while sympathetic magic was on its way out in natural philosophy and the world of the Royal Society by 1688, a few decades earlier it had merited serious consideration by Digby and others, including Robert Boyle. Getting people to think about the range of interests of these early 'scientific heroes', and how what is considered legitmate science and what is not at any one period, are important steps. Likewise, as Darin points out, the concept is in many ways sound: if the powder worked, then it would indeed be a longitude solution, and it is a nice, engaging way of making the connection between longitudinal position and time clear.So, although we should encourage taking a pinch of salt with our powder, it's a story that will continue to run.