The brass filigree has a very intricate design, similar to a snakes scale as seen in the pictures. I would date this lamp from early to mid 19th century. There is a small dent in the base brass piece that could easily be popped back into place.
When I acquired this piece someone had soldered a brass electrical lamp adapter to the top. This was typical when converting these old lamps to electric. Someone in the past tried to use a hacksaw to remove it. In one of the pictures you can see the hacksaw blade marks.
I used a torch and removed it, which exposed the threaded top of the lamp. The hacksaw blade marks are not too deep and possibly could be removed.
The lamp stands 6&1/2" tall and is 4&1/2" wide on the bulbous lower end. All sales are final unless there is a error in the listing. The item "Very Unique Antique Brass and Molded Glass Kerosene Whale Oil Lamp" is in sale since Friday, June 12, 2015. This item is in the category "Collectibles\Lamps, Lighting\Lamps\ Non-Electric\Oil".The seller is "i_812" and is located in Salem, Massachusetts. This item can be shipped worldwide.