CornerHardware.com perhaps explains it best when it applauds the ornate creations that resulted from the novelty of indoor lighting: "In the early days of electricity...light at the flip of a switch was magic. No wonder the fixtures that survive from that time are eccentric and lovely." There's no reason why a case of old wiring should prevent you from purchasing an old fixture or refurbishing one you already have. These pieces can easily and quickly come back to life with some careful and inexpensive rewiring.
Remove any glass shades or other fragile pieces of the fixture and set them aside.
Unscrew any nuts or finials on either end of the fixture. Wrap them in a piece of rag to cushion the jaws of the pliers and avoid damaging them. A threaded tube runs through the fixture and is held in place by these nuts. This tube contains the wiring that runs from the outlet box to the light fixture. Take note of how the old wires are routed before you cut and remove them.
Organise all screws and other small parts as you remove them by placing them in an egg carton or ice cube tray.
Loosen any frozen joints with lubricant.
Clean or replace any internal parts that are worn or corroded. If you have no idea what you're dealing with as far as replacement parts go, gather your old parts and bring them with you to a speciality lighting shop.
Replace the old wiring with a new 18-2 lamp cord.
Disconnect the sockets from their caps and remove the wires from their terminals. Test each socket with a circuit tester. If the light doesn't come on, replace the socket with a new socket and insulator.
Wire a single-socket fixture---one-bulb fixture---working from the socket up to the mount. Attach the wires with wire nuts. For multi-socket fixtures, feed the cord from the mount to the individual sockets.
Mount the socket cap to the light fixture---it will screw into place---then connect the wires to the socket terminals and route the cord back through the socket cap. If you are working with multiple sockets, strip the ends of each wire and connect them with wire nuts.
Mount the fixture to the outlet box by tightening the nuts onto the screws.
Connect the fixture to the house's electrical system by stripping and attaching the fixture's wires to the house wires that protrude from the outlet box. Only strip enough of the insulator coating to connect the wires with wire nuts. Connect the black and white wires to the black and white wires. A bare copper wire attaches to the ground screw on the crossbar.
Reattach the base or body of the fixture by replacing the nuts, or whatever piece held it in place.
Lubricate wires that have to snake through tight spots. The wires may not be black and white. They may have some kind of physical indication of which is the neutral rather than colour-coding. The neutral wire may have a ridge on it. In addition, in older wires, the neutral wire may be silver while the hot wire is brass. This Old House notes that 18-gauge wire coated in rayon rather than PVC is more attractive for pendant lamps whose wiring is exposed.