This signal tower was built in 1843 to provide semaphore communication with Skerryvore Lighthouse. Semaphore is a system of sending visual messages using hand-held flags, discs or paddles. Before radio, the signal tower was the only way of communicating between the lighthouse and the shore station. This was often very difficult due to bad weather and low visibility. The signalman would spend two hours a day in the observation room at the top of the tower hoping to catch a glimpse of signals from the lighthouse through a telescope. A signal would be acknowledged by hoisting a ball to the top of the flagstaff on the roof of the tower. If a keeper was on duty when his wife gave birth, the sex of the new baby would be communicated by using a dress or a pair of trousers on the signal tower flagstaff so the father knew if he had a daughter or a son. The tower was in use from 1844 until 1937.