This notebook is a continuation of N-15-06-04.2. It was used by Absalom M. Kennedy during August-September 1915 as a daily record of experiments and tests with phonograph recorders. The daily record is continued in N-15-09-17. The tests involve various recording machine parts and instruments, as well as variations in the positions of voices, instruments, and recording horns. Kennedy's notes also describe other projects, such as his work for Miller Reese Hutchison on a wireless telephone system and his presentation at a phonograph jobbers convention, and they document Edison's own involvement in the phonograph experiments, including his comments, suggestions, and further instructions. One entry describes Edison's specifications for the "ideal" recorder and includes a drawing by him, which has been taped into the book. Additional comments and instructions by Edison have been taped onto the first page of the book. Other individuals involved in the work include Zachariah P. Halpin, C. D. Ries, and experimenters named Parkhurst and Taylor (probably Henry A. Taylor). Some of the tests and demonstrations were done on orders from Hutchison, Jonas Walter Aylsworth, or Charles Edison. The front cover is labeled "Recording Experiment Book #4. From Aug. 2 To Sept. 16." The pages are unnumbered. Approximately 140 pages have been used.