Artificial glass horizon with funnel in fitted square mahogany case (printed instructions inside lid) made by an unknown English maker, 1805-1815. Consisting of a circular polished brass container with three levelling feet, which holds spirit, covered by a transparent glass plate. When in use, the vessel is filled with spirit using a detachable funnel, leaving an air-gap under the glass to act as a bubble level, which is centred with levelling screws. The funnel is also used to replacing the spirit and for release of pressure when the liquid expands due to heat.
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