Ship’s Binnacle

Binnacles are stands built to hold a ship’s compass and other navigational instruments. They are generally installed by the ship’s wheel so the instruments can be viewed when steering. Binnacles were developed to serve several critical purposes. They raised the compass for comfortable viewing and kept it in place despite the ship rolling. Binnacles also protected the instruments that were both expensive and critical for navigation.

In the mid-18^th century binnacles were built using iron nails which interfered with magnetic compasses, making readings unreliable. This interference worsened as ships construction started using more metal.

The design of this binnacle is a response to the problem of interference. It represents an important contribution to the field of maritime navigation. It was designed and patented by Scottish physicist William Thomson, also known as Lord Kelvin. The two spheres on the side of the housing are made of iron to counteract interference from other metals on the ship. Other models designed by Thomson also featured improved housings to keep the compass level and corrector magnets that could be calibrated to suit each ship. The addition of iron spheres on binnacle’s became standard and is still in use today. The spheres are known as Kelvin’s balls in homage to their inventor.