A rare double "duplex" pressure gauge by J Dewrance of London for Lloyds register.

Made by J Dewrance & Co for Lloyds register of shipping to pressure-test ships' boilers before classing and insuring them.

Dial diameter: 3 1/4 inches.  Two opposing dials scaled from 0 to 800 Pounds per Square Inch (psi).

Original velvet lined case : 4 x 6 inches.

Dewrance & Co. Ltd was established in London in 1835 as a partnership by Joseph Woods and John Dewrance, the company manufactured engine and boiler accessories, such as pumps and gauges.