The camera obscura was a popular sketching instrument in the 18th century. A lens in the draw tube and a mirror at 45 degrees to the horizontal focused the image onto a ground glas screen on the top of the box. A piece of paper was put onto the screen and the image was copied directly. This camera obscura is asociated with Dr Stephen Demainbray, (1710-1782), a science lecturer of the time.
© Science Museum / Science & Society Picture Library