Made saggars (fired clay containers used to hold ceramic items in the kiln whilst firing.) The saggar-makers bottom knocker was the saggar makers assistant, usually a young boy, who was responsible for knocking clay into a large metal hoop using a flat mallet called a mawl, to form the bottom of the saggar.
The saggar-maker would then remove the hoop, and form the sides of the saggar onto the base- a much more skilled job than bottom-knocking (testing for cracks by knocking.) Some saggar-makers also had a frame filler, who did a very similar job to the bottom-knocker, but prepared the clay to make the sides of the saggars, rather than the bottom.
http://www.thepotteries.org/bottle_kiln/saggar.htmStephanie.