The
Titanic's forth smokestack was actually a functional unit, but was not tied in to the boilers in any way. The kitchens & restaurants were all in the after part of the ship, on multiple deck levels, and the heat and smoke from the various ovens and cooking devices was expelled from this stack. Many photographs of the
Olympic class vessels in port show a thin wisp of smoke from this stack-evidence their kitchen crews were hard at work. This stack also had an internal ladder on its forward inner surface-there is a famous photograph of a stokers blackened face at the top of this stack--