Using Wounded Dogs to Navigate Ships on the High Seas
By Tom Logsdon
Finding the latitude of a sailing ship can be surprisingly easy: sight the elevation of the Pole Star above the local horizon. Finding longitude turns out to be quite a bit harder because, as the earth rotates, the stars sweep across the sky 15 degree every hour. A one second timing error thus translates into a 0.25 nautical mile error in position. How is it possible to measure time on board a ship at sea with sufficient accuracy to make two-dimensional a practical enterprise?
One 18th century innovator, whose name has long since been forgotten, advocated the use of a special patent medicine said to involve some rather extraordinary properties. Unlike other popular nostrums of the day, the Power of Sympathy, as its inventor, Sir Klenm Digby, called it, was applied not to the wound but to the weapon that inflicted it. The World of Mathematics, a book published by Simon and Schuster, describes how this magical remedy was to be employed as an aid to maritime navigation.
Before sailing, every ship should be furnished with a wounded dog. A reliable observer on shore, equipped with a reliable clock and a bandage from the dog's wound, would do the rest. very hour on the dot, he would immerse the dog's bandage in a solution of the Power of Sympathy and the dog on shipboard would yelp the hour.
As far as we know, this intriguing method of navigation was never actually tested under realistic field conditions, so we have no convincing evidence that it would have worked as advertised.