You can read more about how Doug came across these images on the Metal Type forum here: Linotype: The Book.
Mergenthaler’s own factory in BaltimoreOttmar Mergenthaler in his Baltimore, MD factory surrounded by his employeesInterior of the Baltimore factoryShop in Berlin, Französisch Straße 33a, where the Linotype was first shown in GermanyThe first business premises of the Mergenthaler Setzmaschinen-Fabrik in BerlinLinotype factory in Brooklyn, NY in 1888 (left) and 1892 (right)The Mergenthaler Setzmaschinen-Fabrik GmbH headquarters building on Chausseestraße 23 in Berlin, Germany circa 1936
More factory photographs: Don’t miss some great photographs from the Intertype factory in Brooklyn, USA in 1966. Intertype Factory, 1966