ClipArt ETC
"An improved form of the lamp, in which a portion of the cone B is removed to show the two parallel flat wicks A, A, which have each a separate slit or opening in the cone. C is the coincident winder for raising or lowering the wicks in the tubes, by which the wicks can be moved separately or simultaneously as desired. D is a lever for raising the extinguishers E, whereby not onl is the light instantly extinguished, but the wicks are also covered and protected from dirt, while all evaporation by the wick-holder is prevented." —The Encyclopedia Britannica, 1910

Duplex Burner

"An improved form of the lamp, in which a portion of the cone B is removed to show the two parallel…

"The Duplex is made in two equal parts, each being capable of being worked alone. Each section consists of a semicircle of upright tubes forming the boiler proper, fitted with the diaphragm a, horizontal pipes forming the furnace f, a flow pipe b and a return pipe c, and an outlet d for removing sedimentary deposits from the interior." — Encyclopedia Britannica, 1893

Duplex Tubular Boiler

"The Duplex is made in two equal parts, each being capable of being worked alone. Each section consists…

"A plate of glass about 2.5 inches square is ruled with twenty-one lines in one direction .1 inch apart, and two lines in the other direction 2 inches apart. The extreme lines of the set therefore form a perfect square of 2 inches. These lines are ruled with exceeding accuracy and care, but provision is left for ascertaining any errors that remain either as to distance or want of perfect squareness." —The Encyclopedia Britannica, 1903

Micrometer

"A plate of glass about 2.5 inches square is ruled with twenty-one lines in one direction .1 inch apart,…