A translation of The Collected Papers of Albert Einstein is being pub-
lished by Princeton University Press under the supervision of Diana
Kormos Buchwald, General Editor. Volume 10, containing translations
of selected texts, was prepared by Ann Hentschel, translator. Klaus
Hentschel was the consultant, and Alice Calaprice was the copyeditor.
At Caltech, Rosy Meiron and Jennifer Nollar assisted in the translation;
Osik Moses prepared the index and, together with Rudy Hirschmann,
checked and typeset the final manuscript. These volumes, produced in
paperback, are intended to be read in conjunction with the documentary
edition, as they contain none of the editorial commentary of this edition.
NOTE ON THE TRANSLATION