The original German edition of this book dates from 1920, the English translation dating from 1924 (the red-covered Dover edition). It's a decidedly original piece that made a real attempt to come to grips with the ambivalence of the subject, and in particular introduces the idea that e/m wave crests are events that observers in relative motion can agree about. This isn't true, bur it isn't obvious it isn't true, and the whole idea seems to have been fruitful in provoking thinking about anti-realism in Born's assistants - first Pauli who produced his own book on relativity in 1921 and unlike Born did not feel he had to revise it; then Heisenberg in another direction. Unfortunately when it became time to reprint it in 1962 Born refused to sanction it in its original form so the current edition is perfectly respectable and correct but in my view has lost some of the verve and interest of the original; like most books on relativity you don't feel quite satisfied but you're not quite sure why. It's good, though: Born was a protean figure with the gift of attracting brilliant assistants and seeing them given the maximum credit for their contributions, to the extent that his own role tends to be forgotten, and some of this generosity affects the quality of his writing. But like others I feel there would be a place for a new publisher (maybe Folkestone books?) to republish Dover books that have gone out of print; one thinks of O'Rahilly's highly original (and surely wrong?) take on e/m theory. Where can one get it now? It's disappeared like Born's red edition.