The Factory Kiln.

The factory kiln was a large brick structure that could hold 200,000 pipes during a single firing. It had the capacity to sustain production of a million pipes per month in its heyday. During the firing, the saggers were stacked alternately around the kiln, and the pipes were fired for up to 48 hours, with the kiln reaching its maximum temperature after 32-to-36 hours of operation. There was an opening in the roof of the kiln that was used for pouring in salt for a glaze. The pipes were allowed to cool for the same amount of time as they were fired in order to prevent crazing (or cracking) of the glaze. The top photo and sketch here are from 2009; the bottom photo shows the kiln's firebox circa 1976 prior to being repaired. (See this PDF of the sketch.)