Complex sentence: Halcomb installs the first electric-arc melting furnace in the United States; it later is known as "Old No.1" and becomes a designated American Society for Materials historical monument, located at Station Square, Pittsburgh, Pennsylvania.
Split into simpler sentences: Halcomb installs the first electric-arc melting furnace in the United States. This furnace becomes known as "Old No.1" and is designated an "American Society for Materials historical monument", later it is moved to Station Square, Pittsburgh, Pennsylvania.