There are a lot of details in this kiln. Looks like over 10 arches in total. Here are the arched hobs.
When I first saw pics of them in one of Donovan's other kilns I thought it over kill. They are 4 1/2" not 9" bricks. The stepping up of the bricks in the chimney is creating a rather large collection box to cool down the exiting flame.
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