Hanging parlor lamps of this type tend to date from the last quarter of the 19th Century. Many did have markings that help identify the maker, such as names or patents on the burner or wick adjuster knob, often removed when they were electrified during the 1950's through 80's. Values for them depend a good deal on their current condition, the glass type used for the shade or font and the level of decoration. While not mass produced in the modern sense of the term, most lamp companies made their own line of such lamps, so they do survive in relatively large numbers.
As the glass shades are a big part of the value for Victorian lamps, great care should be taken when handling or cleaning them. Over warm water can cause glass shades to crack, regular dusting would be safer and better than occasionally washing them. The brass work can be sealed with lacquer after polishing, maintaining the sheen for many years. Values for Victorian lamps have had a up and down love affair with Collectors over the years, with a big swing in value from the late 1980's through the 90's. Today values have cooled of somewhat, but examples in good condition still sell at a premium over pieces in need of restoration. Currently comparable lamps to the one shown often sell at Auction in the $275-350.00 range, but some rarer Opalescent Cranberry Hobnail glass examples can go for over $1500.00.