title: Correction.
abstract: In my report on the Echo Lakes Symposium on Cosmic Rays (Science, September 2, 1949) the pi- and micro-symbols were interchanged, in the line before last of the second column, p. 242, and in the first line of the third column in the same page. The portion of the text containing these two lines should read: ". . . the latest values for the masses of the micro- and the pi-meson (215 and 285 electron masses respectively) and for the mean life of the pi-meson (0.63x10(-8) see)." In a recent letter to the writer, Dr. Barkas states that this value for the mean life of the pi-meson has been superseded by more accurate measurements. These measurements, made on positive pi-mesons, give a mean life of 1.97x10(-8) sec. Dr. Barkas also indicates that new mass measurements give 276 electron masses for positive or negative pi-mesons and 210 electron masses for positive micro-mesons.
authors.forename: B
authors.initials: B
authors.lastname: Rossi