that's very pretty.
The initials stand for Pittsburgh Lamp, Brass and Glass Company (which has already been stated). The factory was located in Pittsburgh.
You have what sounds like a "ewer" lamp (the ewer is a wine pitcher from the Mediterranean area. Most of these are electric lamps. PLB&G Co ("Pilabrasgo") lasted into the 20's.
The company started production with oil lamps.
I would assume the 1792 is either a part or style number.
here is some corporate history on the Pittsburgh Brass Co. from The Historical Society of Western Pennsylvania and the U.S. Patent Office.
1889. Pittsburgh Brass founded Jan 12. Thomas Hipwell, one of the original founders, assigned at least 2 U.S. patents to the company for improvements in brass fount design from 1890-96. William Hoerle assigned at least 7 wick raiser and misc. lamp patents to the company also in that time frame. This would lead one to believe that they were definitely in the business of manufacturing brass founts and burners(?) during that period.
1894: They advertised The "Pittsburgh Lamp".
1898: Name changed to the Pittsburgh Lamp and Brass Co.
1901: Reorganized as Pittsburgh Lamp, Brass and Glass Co. after acquiring the Kopp Lamp and Glass Co. and Dithridge & Co. businesses.
My guess is that Pittsburgh Brass was only selling brass lamp parts from 1890-94. They then started making their own line of lamps, possibly buying misc. cast steel (?) and glass/porcelain parts, assembling and selling the finished products using brass parts of their manufacture from 1894-1901. In 1901 they started with their "Success" line and began making glass lamps with the acquisition of Kopp Lamp and Glass and Dithridge & Co. When they acquired the Kopp and Dithridge Co's., they now could supply most of the parts internally and lamps probably became the focus of their business.
Also 1901: One of their business letters mentions "electric shades" which might mean that they were starting into electric lamps around that time also.
