two-drum power boiler
71Steamroller — A steamroller (or steam roller) is a form of road roller ndash; a type of heavy construction machinery used for levelling surfaces, such as roads or airfields ndash; that is powered by a steam engine. The levelling/flattening action is achieved… …
72Elephant clock — The elephant clock was a medieval Muslim invention by al Jazari (1136–1206), consisting of a water powered clock in the form of an elephant. The various elements of the clock are in the housing on top of the elephant. They were designed to move… …
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