This notebook covers the period February-July 1881. The entries are by Charles L. Clarke and relate to dynamos. Included are notes, calculations, and drawings of the Porter-Allen central station dynamos, the South American portable dynamo, sizes E, F, and C dynamos, a steamboat dynamo, and a flywheel for an Armington-Sims steam engine dynamo. Thirteen loose pages found in the book contain additional notes, drawings, and calculations. The label on the front cover is marked \"C. L. Clarke\"" and \""Magnets.\"" The book contains 278 numbered pages.

Blank pages: 72-99, 104-109, 224-253, 268-269, 278."