Chambers's Journal of Popular Literature, Science, and Art, Fifth Series, No. 107, Vol. III, January 16, 1886

Communication between the vessels of the fleet is effected at night by means of the flashing light worked on the short and long flash principle, invented by Captain Colomb, R.N. There are few sights more suggestive of the advance in modes of communication and the development of the inventive faculty than that of the admiral ‘talking’ to his captains by means of the flashing lamp in the darkness of the night and far out on the trackless ocean. It may be necessary during the night to alter the course of the squadron. If the course indicated at sunset be due north, and it be required to alter the direction to west, all lights on board the flagship, except the flashing light, are carefully obscured, and the brilliant rays of a solitary lamp leap through the darkness conveying the order, ‘Alter course to west.’