Additional information edit: On the inside of the shade at the bottom inside of the shade, it is written numerous times: Pat'd Oct 20.08. I assume this means that it was patented on October 20th, 1908. Notice that there are a couple flaws with this lamp. At some point, it appears that some of the slag glass was chipped off around the edges on the inside (not visible from the outside). This can be seen in the photo of the inside of the glass panels.
It in no way messes with the function or outward appearance of the lamp. Secondly, the metal joints are slightly separating on two of them (directly opposite of each other as it happens). In response to messages: There are no cracks on any glass panels on either the inside or the outside. The item "Bradley and Hubbard arts and crafts two-tone slag glass table lamp" is in sale since Monday, September 3, 2018. This item is in the category "Antiques\Decorative Arts\Lamps".The seller is "merrillsferals" and is located in Stratford. This item can be shipped worldwide.