2

Hydraulics.

MEdes’s SCrew explain'd. The Na-ture and Structure of News ham’s Wa-ter-Engine, Newcomen’s Fire-Engine, Savery’s Fire-Engine, andPaine’s improvement of Fire En-gines explain'd. Of the Æolipile. TheTheory of the Tides at large explained\

B Y HYDRAULICS we are tounderstand the Science of the Mo-tion of Fluids, and the Constructionof all Kinds of Instruments and Machinesrelating thereto; also the Nature of Springs,the Theory of the Tides, &c. are usuallyexplain’d under this Plead.

The Motion of Fluids , viz. their Descentor Rife below or above the common Sur-face or Level of the Source or Fountain, iscaused either (i.) By the natural Gravityor Pressure of the Fluid contained in theReservoir or Fountain; or (2.) By thePressure or Weight of the Air on the Sur-face of the Fluid in the Reservoir, whenit is at the same Time either taken off, ordiminished, on some Part in Aqueducts,or Pipes of Conduit. (3.) By the Springor elastic Power of compressed or con-idensed Air, as in the common Water-En-gine. (4.) By the Force or Pressure of

Pistons,