This beautiful device is called a sunshine recorder and true to its name, it records the amount of sunshine at a given location. The sunshine recorder uses either the sun itself as a time scale or a clock. The brilliance of the recorder lies in the fact that a glass sphere focuses the sun’s rays on a card inside the ball which in turn measures the sunshine.
The original sunshine recorder was invented in 1853 by John Francis Campbell and was adapted and improved a few years later by George Gabriel Stokes. Campbell’s idea involved placing a glass sphere in a wooden bowl and the sun would burn a trace on the bowl as the earth circled it. The invention has undergone some improvements since then.