First English language edition, first printing, representing the first appearance of any of Einstein's writings in English. Translated from the third German edition of 1918, it includes an additional chapter (Appendix III - The Experimental Confirmation of the General Theory of Relativity) which Einstein was pressed to write by Robert Lawson, the translator. Lawson, as well as publisher's, Methuen, were keen that it should be as accessible as possible to the lay reader and Einstein is said to have written it within hours of the request. xiv, [2], 138, [2], 8pp, with portrait plate frontispiece, diagrams and formulae in text. Red cloth-covered boards, blind stamped titles and rules on upper panel, black lettering and rules no spine. Tall 12mo. Cloth is worn, gently rounded on corners, a little rubbed and rounded at ends of a sunned spine. Text block edges dust dull. Uneven tanning on endpapers, Faint and occasional spotting on first and last few pages. Front hinge cracked at base, a little shaken.
