The Britannica, first produced in Edinburgh in 1768 in one hundred weekly installments, sixpence apiece, wears the same halo of authority. It seemed finished—in every edition. It has no equivalent in any other language. Even so, the experts responsible for the third edition (“in Eighteen Volumes, Greatly Improved”), a full century after Isaac Newton’s Principia, could not bring themselves to endorse his, or any, theory of gravity, or gravitation.
