There is an English translation of this book on pages 217-259 of Quantum Theory and Measurement', edited by J.A. Wheeler and W.H. Zurek, Princeton University Press, Princeton NJ, 1983. According to Albert Messiah, footnote 1 on page 157 of Quantum Mechanics, originally in French, translated into English, my copy published by Dover 1999: "A very concise and simple presentation of the measuring process in Quantum Mechanics is given in [this 1939 book by London and Bauer]".