Dipping Needle

An Elizabethan seamen and compass maker named Robert Norman is credited with inventing the dipping needle around 1580. Norman noticed that when he balanced compass needles, then took them off and magnetised them, they always dipped down at one end. He sought to rectify the problem by shortening the side of the needle that dipped, but failing to do so he discussed the phenomenon with the navigator William Borough, who was appointed Comptroller of the Navy in 1583. Norman and others then made various experiments confirming the existence and degree of dip.

In the early seventeenth century, the dipping needle was seen as a means of discovering latitude when weather conditions prevented celestial observations. By mid-century the work of Henry Bond, a London navigation teacher, stimulated interest in whether a dipping needle could also be employed to find longitude.

A committee established by the Royal Society in 1664 eventually concluded that readings from a dipping needle were unpredictable due to unknown variables affecting the needle's magnetic properties.

Even so, there continued to be natural philosophers and instrument makers who believed the dipping needle could be transformed into a reliable navigational instrument for determining latitude. When Cook left Plymouth in August 1768 he carried aboard the Endeavour a dipping needle provided by the Royal Society, and instructions to 'observe the inclination of the Magnetic Dipping needle from time to time.'