"Spencer Browning & Rust London" and "SBR"
radius 13.75 inches
This octant has an ebony frame and flat brass index arm. The ivory scale is graduated every 20 minutes from -2o to +99o40'
and read by vernier with tangent screw to single minutes of arc. There is also a
back sight and a back horizon glass that can be used to measure angles greater
than 90o. This instrument was probably made around 1800. It belonged to Mount St. Mary’s College in Emmitsburg, Md.
Spencer, Browning & Rust