The heliostat is designed to reflect a beam of sunlight in a fixed direction, and uses a clockwork driven mirror to counteract the apparent motion of the sun through the sky. The resulting steady beam of sunlight would often be projected into a laboratory for experiments requiring intense light, physical optics studies, microscopy, analysis of the solar spectrum, etc.
This example has an octangular mirror, a clockwork mechanism, and tri-leg base with leveling screws. The inscription on the clock housing
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