Exploratory tests under a variety of conditions were made during Bell Telephone Laboratories' studies on stereophonic reproduction to determine the effect of arrival time as a factor in localization. The recent rapid rise of interest in stereophony appears to warrant a summary of these old results (1934), for which the Laboratories has granted permission. It is shown that arrival time differences have essentially the same effect whether they are generated in the pickup room, listening room, or in the electrical system. They can therefore be made to add or compensate. Small differences (0-3 milliseconds) cause large shifts of localization angle, but the effect becomes relatively constant for larger differences. Time differences can be compensated by level differences. The results of two other experimenters are given for comparison. It is concluded that reasonable agreement is attained, considering the small total amount of data, but that more experiment is required to establish accurate quantitative relationships for practical stereophonic reproduction.