This is an antique, 19th century, adjustable height 'double student lamp' or duplex lamp in original, non-converted condition in brass with green cased glass shades that was manufactured by Plume & Atwood. This has never been converted to electric and appears to be in fine working condition from the images. The chimneys have been replaced. which will not impact value. The estimate is based on actual recent past recorded auction sales of comparables. Retail 'asking prices' can be higher and vary.