1st Edition. First American Edition, in original publisher's Navy Blue Cloth, gilt stamped on spine. First American Edition, printed in the Great Britain at the University Press, Aberdeen. Four Lectures Delivered at Princeton University, May 1921. Some minor rubbing on the spine and back and the usual shelf usage. Book is tight and very good condition with toning to the pages with age. The book is over 100 years old. All pages intact. 123 pp including index. Housed in a brown slipcase with E = mc2 embossed.