John Bartholomew (1805-61) was the first of the family name to join a business founded in 1784. The period of the late nineteenth and early twentieth centuries represented the height of the companies influence. The main influence of growth in the business was John George Bartholomew (1831-93). He was the inventor of layer colouring, first introduced in his maps in 1888. One of the firms first significant productions was the ‘Imperial Map of England and Wales’ derived from the Ordnance Survey. The map is a typically detailed one engraved on steel. It is drawn on a scale of half an inch to the mile. Beresiner ‘British County Maps’ pp. 52-3.