The words mill and factory are often used interchangeably to describe a building or group of buildings where goods are manufactured or assembled chiefly by machine. The source of power in six of the mills being discussed was water from the River Sheppey. Both the factories in Coombe Lane were situated on a small tributary of the Sheppey River which flows north (now largely culverted) beside Coombe Lane to join the Sheppey at Bowlish. The Coombe House Factory was probably water-powered but the Coombe Lane Factory further upstream was not and was worked by hand.