"Prior to the introduction of the cup and cone, a form of tunnel-head in which no valve or cone exists was employed. A hollow annular chamber BB is built in the upper portion of the stack, communicating by arched cavities A, A, A with the shaft, and also with the exit gas main C; a considerable fraction of the gases then passes out through the arched vavities when the materials are heaped up to the level of the charging door D. With small furnaces the wall between the shaft and the chamber B is made of past or wrought iron; in some cases the gas has been collected through a central tube in the axis of the shaft supported by groins springing from the shaft and the ore." — The Encyclopedia Britannica, 1893

Collecting Top

"Prior to the introduction of the cup and cone, a form of tunnel-head in which no valve or cone exists…

An illustration of men collecting sponges.

Sponge Fishing

An illustration of men collecting sponges.