Bowl of Campbell sunshine recorder, brass. No lens (the lens/ glass ball shown in the image is probably from a different instrument, AST0767). No card.

The bowl's rim features the Latin motto "HORAS NON NUMERO NISI SERENAS" ("I count only the serene hours").

Typed on accompanying piece of paper: "Sunshine recorder made by Mr J. F. Campbell, in use at Greenwich from May 1876 to the end of 1886. Bright sunshine was recorded as a scorch mark on a strip of black millboard."

Sunshine recorders are positioned on a local meridian (north-south line) and record the number of hours of sunshine. Each day, a new card strip is placed into the grooves behind the glass sphere. As the Sun crosses the sky, the sphere acts as a magnifying lens, burning a line into the card that’s specially designed to scorch rather than burst into flames. The strip varies in length and position according to the seasons.

The idea was first devised by John Francis Campbell in 1853 and was later developed by the physicist Sir George Gabriel Stokes in 1879. Although simple to use and easy to maintain, the instruments are susceptible to variable results and need human intervention to replace the card strip each day, hence modern meteorological observatories rely on electronic sensors instead.