|Craig Sturge on posted in Facebook|
Update: Chris Litherland's photo of the mill. In a Facebook posting of this photo, Chris provided the description:
Here's a photo from a couple of weeks ago of the Edgar Thomson Steel Mill in Braddock.
The Edgar Thomson Steel Works was designed and built due to the invention of the Bessemer process, the first inexpensive industrial process for the mass production of steel. In the process, air blowing through the molten iron removed impurities via oxidation. This took place in the Bessemer converter, a large ovoid steel container lined with clay or dolomite.
The mill was built for Andrew Carnegie by Alexander Lyman Holley, who found a manager to run the mill, Capt. William Jones, a Civil War veteran. In 1875, the Edgar Thomson Steel Works' hulking Bessemer converter produced its first heat of liquid steel, destined to become 2,000 steel rails for the Pennsylvania Railroad. These steel mills are what built this region and the world during the early 1900s. Now this mill is one of that last steel mills left in the US, and is also among one of the oldest.