This notebook covers the period March-April 1880. Most of the entries are by Charles L. Clarke. There are also a few entries by Edison and Francis Upton. Included are calculations and tables relating to conductors for the electric lighting system; calculations relating to tests of the system made by Professors Cyrus Fogg Brackett and Charles Augustus Young of Princeton; calculations, drawings, and notes on the shrinkage of carbonized filaments; drawings of pulleys and belts for a dynamo room; and notes on a "Trial of Rotary Engine Engineering Jan. 1, 1875." There are also a series of calculations by Edison about central stations and electric power distribution and a few calculations by Francis Upton about electric power distribution. The name "Clarke" is inscribed on the inside front cover. The inside back cover contains the notation: "Clarke Table of Volts - Ohms - Foot-lbs." There are 284 numbered pages, and the book has been used in both directions.

The notebook pages appear in the following order: pp. 1-201; pp. 284-202 [in reverse page-number order].