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Thursday 20 May

By Maritime Media Volunteer, Don Knibb.

Not long after my blog on the Hull Time Ball was published on this website, a friend sent me a link to a book called Longitude by Dava Sobel.

Longitude recounts in detail the story of John Harrison, the development of his chronometers and his ultimately successful attempt to win the prize offered by the Board of Longitude for solving the age old problem of establishing longitude at sea.

Browsing around the subject, it became apparent that the Board's prize money – which was substantial – attracted many other proposals, some more realistic than others.

Of these, the downright wackiest must have come from one Sir Kenelm Digby who incidentally was played by Stephen Fry in the 2000 TV movie of the book, also called Longitude.

Digby had grown interested in a curious substance known as weapon salve, with which you could supposedly heal wounds at a distance in miraculous fashion.

The miracle – never clearly explained for fairly obvious reasons – lay in the proposition that you could heal wounds by applying weapon salve not to the wound itself but to the weapon that had caused it.

What has this got to do with finding longitude? Good question. Digby seems to have further developed the idea of weapon salve by inventing something he called a 'powder of sympathy.'

This strange potion could allegedly heal wounds if applied to an article of clothing or a bandage which had once been worn by the victim. Distance of bandage from wound was no object.

With impeccable logic, Digby proposed that ships could carry a wounded dog when they embarked leaving a used bandage behind, and that a reliable assistant at the home port be entrusted to apply the powder of sympathy to the bandage at precisely the right moment every day. The dog's wound would smart and the dog would yelp, revealing the exact time at Greenwich.

There does seem to be a flaw – OK, one of many – with the idea, though. Had the powder of sympathy actually worked, the dog's wound would heal and would presumably no longer smart when the powder was applied and the dog would therefore not yelp.

Digby does not seem to have addressed this, which may not be the only reason he didn't win the prize.