Candles, along with firelight, were the only sources of illumination after dark in the 1700s. Wall lights such as these were usually fixed on either side of a mirror so that the reflection multiplied the flames of the candles.
These wall lights were modeled to represent flaming torches. The Getty Museum has a drawing of this design; it is thought to be by the same hand, Jean-Louis Prieur. Lights of the same design appear in a watercolor drawing of the grand salon in the Château de Chantilly, the home of the Prince de Condé on the outskirts of Paris.