[This note covers all of the notebooks in Group 4: Tube Books.]

The thirty-five extant notebooks in this group (Nos. 1-36; Book 31 has not been located) cover the period July 1905-February 1914. Most entries in the first twelve books are by Edison. The remaining books show a rapid decline in the number of Edison entries. By Book 16, there are only occasional calculations and brief notes by him. Most entries in the later books are by unidentified experimenters. The books contain records of experiments relating to the nickel tubes used in Edison's storage batteries. The tests are numbered from 90 through 9950. Tests 1- 89 can be found in N-03-06-19 (see "Notebooks by Edison"), which contains other experimental work and is not included in this numbered group of tube books. A new series of enumerated tests begins in Book 16, with numbers from 1A through 13657 (the "A" is dropped after test 10569). The first page of Book 1 contains the following notation by Edison: "Experiments with perforated tubes & flake metal with various sticky sub[stances] & proportions & manipulations." The tests involved varying the compounds used to hold the nickel flake in the tubes, as well as altering the process by which the flake was tamped down in the tubes. Labels on the front covers of some of the books contain notations by Edison regarding the importance of the data contained therein.