Note 76 — Chapter XIII
Reading edition
Tubbing is now adopted in many cases as a substitute for brick-walling. The tubbing consists of short portions of cast-iron cylinder fixed in segments. Each weighs about 4-1/2 cwt., is about three or four feet long, and about three eighths of an inch thick. These pieces are fitted closely together, length under length, and form an impermeable wall along the sides of the pit.