Lawrence & Mayo Henri Chatelain Rotary Map Measurer c.1900
A very nice example of a 'HC' (Henri Chatelain) map measurer, retailed by Lawrence & Mayo of London. 29mm in diameter, this is a very small and beautifully made instrument for measuring distances on maps (Francis Barker made similar instruments to these at around the same time, their version was known as 'The Rotameter'). The inner and outer dials read to 25 feet and twelve inches respectively. The wheel is graduated in 1/32 inches. Although primarily intended for use with maps, this instrument can also be used to measure distances on any flat surface, up to a maximum of 25 feet. Dating from the early 20th century, this map measurer was made in France and is marked on the back of the case: 'France, Depose HC, Lawrence & Mayo, London'. Lawrence & Mayo were founded in 1877 in London as opticians and makers of scientific instruments. By 1925 they had headquarters in New Oxford Street, London and showrooms all over the British Empire, from Alexandria to Bombay.