With tube of about 5 to 6mm bore. The scales are graduated on nickel plated brass tube, protected by a glass tube with vernier reading to 0.002 inch and 0.05mm. The vernier is actuated by rack and pinion. The two scales read from 25 to 32 inches and from 640 to 810mm. The cistern is made of glass. The change in the level of mercury to touch the zero ivory point, is affected by means of a thumb screw at the base. The whole assembly is mounted on a polished wooden board fitted with milk glass reflector and thermometer. It is supplied without mercury and glass case.