1855 Chamberlain Ritchie Survey Compass, only 1 known by this maker

Description

This is only known example of a surveying compass by Chamberlain & Ritchie.
Nice shape and comes with a box, but I don’t think the box is original to the compass.
There are no sight vanes with this compass so I am not sure how a person would even use it? It measures 6
" long and has a 4 3/4" compass needle.
Postage is .00 if within the US, more  If you are outside the US; no charge for careful packing.
Here is some information on E.S. Ritchie and Chamberlain & Ritchie:
Edward Samuel Ritchie
1814-1895
Edward Samuel Ritchie an American inventor and physicist, is considered to be the most innovative instrument maker in nineteenth-century America, making important contributions to both science and navigation. He was born on August 18, 1814, the son of John and Eliza Ritchie. As a young child Ritchie displayed a great aptitude for both the arts and mechanical sciences. In 1839 he established a hardware business in Boston, Massachusetts with a partner forming the firm of Palmer & Ritchie. From 1842-1849 he ran a nautical chandlery in New Bedford. After working as an amateur sculptor, he founded a business in 1850 with N.B. Chamberlain to manufacture mechanical and electrical instruments. By 1862 the company was known as Edward S. Ritchie & Co. and in 1867 the firm name became E.S. Ritchie & Sons.
Ritchie is credited with inventing the first practical liquid-filled compass circa 1860. He produced a compass for the famed Civil War iron clad
USS MONITOR
in 1861 and was awarded his first patent for the invention on September 9, 1862 -- at the height of the war! A number of improvements and subsequent patents followed.
Ritchie began making compasses for the U.S. Navy soon after the start of the Civil War, and within a few years he had developed the first successful liquid compass–a feat that has been described as the first major improvement in compass technology in several hundred years.
Ritchie compasses soon became Navy standard.
They were also widely used by American merchant mariners.
The business he began in 1850 became E. S. Ritchie & Son in 1866 and E. S. Ritchie & Sons in 1867, and moved from Boston to Brookline in 1886. Following Ritchie’s death, his sons transferred the scientific instruments to the L. E. Knott Apparatus Co., while retaining the nautical instrument line. The firm was incorporated in 1939. It is today located in Pembroke, Massachusetts, and known as Ritchie Navigation.
The elder Ritchie died in 1895, but his sons carried on the business, which still survives today as E. S. Ritchie & Sons, Inc. Pembroke, Massachusetts. Today still privately held by the Sherman Family in Pembroke, MA, Ritchie Navigation continues to be the Marine Industry leader in the manufacture of recreational and commercial magnetic compasses.