This compass is similar to the one for which Charles Schmalcalder, a London instrument
maker, obtained a British patent in 1812. It is designed so that a surveyor can read the card while
sighting a distant object. It has a tall folding sight at north, and at south, a shorter sight with a
prismatic eyepiece at its base. The floating card is colored bright green; the numbers around its
edge read correctly when seen through the prismatic eyepiece. James Green was born in England
in 1808, moved to the United States around 1832, and opened an instrument shop in Baltimore.
He opened a second shop in New York in the early 1840s, and retired in 1885. The United States
Weather Bureau transferred this compass to the Smithsonian in 1954.
