A replacement semaphore system was sought, and of the many ideas and devices put forward the Admiralty chose the simpler semaphore system invented by Sir Home Popham. A Popham semaphore was a single fixed vertical 30 foot pole, with two movable 8 foot arms attached to the pole by horizontal pivots at their ends, one arm at the top of the pole, and the other arm at the middle of the pole. The signals of the Popham semaphore were found to be much more visible than those of the Murray shutter telegraph. Popham's 2-arm semaphore was modelled after the 3-arm Depillon French semaphore. An experimental semaphore line between the Admiralty and Chatham was installed in July 1816, and its success helped to confirm the choice.