An essay on currents at sea [electronic resource] : By which it appears, There is Reason to apprehend, that the Sea is not a Fluid in a State of Rest, except those Motions which are caused by the Impulse of Winds, and that known by the Name of Tides: And consequently, That this Earth is not of a uniform Density, according to the Supposition of Sir Isaac Newton; but that the Currents of the Gulph of Florida, also on the Coast of Brasil, and the Northern In-Draught on this Western Coast, are Currents of Circulation, kept up by different Densities in this Earth, and its Motion round its Axis. By Joseph Mead.