Victorian lighting, for most of the era, meant a valve and a match, not a switch. The interior was lit by gas: a flame burning at the end of a pipe, behind a glass shade that softened the light and caught the soot. The fixtures were built for fire, and it shows in what survives.
A gasolier hung from the ceiling like a chandelier but carried gas jets instead of candles or bulbs. Wall brackets swung out on a pipe so the flame could be lit and adjusted. The shades sat open at the top, because a gas flame needs to breathe and the heat has to go somewhere. Look at an early fixture and the design logic is all combustion: valves, keys, upward-venting shades.
The transitional fixture
Then electricity arrived, and for a while the two systems overlapped. That's where the combination gas-electric fixture comes from, a transitional object with gas jets pointing up and electric sockets pointing down, hedging between a technology on its way out and one not yet trusted. A house wired in the 1890s often kept the gas lines live as a backup. Those hybrid fixtures are among the clearest date markers a Victorian interior offers.
The move to the filament bulb changed the fixture's whole shape. Once the light came from a sealed bulb instead of an open flame, shades could close at the top, sockets could point in any direction, and the venting logic disappeared. A fixture designed for electricity looks freer because it is; it no longer has to feed a fire.
We see the whole arc come across the bench: gasoliers converted to electric, combination fixtures with both systems intact, early electric pieces still carrying the caution of the transition. Each one is wired to current safety before it leaves.
Salvager's Note: Jets pointing up with sockets pointing down means a gas-electric combination fixture, and it dates the house to the electric transition, roughly the 1890s to 1910s. Any converted gasolier should be rewired before use.