The delineator is an aid for drawing, and particularly for achieving perspective. Such devices have a long history, dating from the fifteenth century. The oldest and best known is the camera obscura. A device using grid frames and one or two sighting pinholes was developed in the seventeenth century. In 1669 Christopher Wren presented his 'Perspectograph' to the Royal Society, and variations of this continued into the nineteenth century. A delineator was patented in 1778 by William Storer, for which he claimed great convenience over the camera obscura, because sunlight was not needed, and the device could be used at night, by candlelight.
George Adams, Junior (1750-1795) illustrated in his Geometrical and Graphical Essays of 1795, a complicated apparatus involving rollers. The present instrument is an earlier and simpler version of this, incorporating the frame and a single pinhole., mounted on the box containing the apparatus. It will have been made under the supervision of George Adams, Senior (1709-1772) in about 1765.
The business of George Adams, Senior, was in Fleet Street; it was variously named, and was at 'Near Water Lane, Fleet Street' in 1757 until numbers were allocated in July 1766, when the premises became known as 60 Fleet Street. From the way the signature with address is given on the instrument, it may have been produced before the numbering.