The Lewis lamp is a type of light fixture used in lighthouses. It was invented by Winslow Lewis who patented the design in 1810. The primary marketing point of the Lewis lamp was that it used less than half the oil of the prior oil lamps which they replaced. The lamp used a similar design to an Argand lamp, adding a parabolic reflector behind the lamp and a magnifying lens made from 4-inch-diameter (100 mm) green bottle glass in front of the lamp. A similar variant using a parabolic reflector was created by the inventor of the Argand lamp, Aimé Argand. While the Argand variant became widely used by European lighthouses, the Lewis lamp design was selected by the United States for use in American lighthouses.