© Science Museum / Science & Society Picture Library
This quadrant was produced as a paper plate for a book which could be removed and pasted on to a board. It was designed in 1700 by John Rowley, but was out of date in 1756 when it was published, since it is based on the old calendar. A star was viewed through the sights, and a plumb bob gave its altitude. The positions of principal stars and other astronomical and mathematical data are also provided.