This early dynamo electric machine and experimental scientific apparatus looks like it belongs on Edison's Menlo Park Laboratory bench or on a lecture table in front of Nikola Tesla. The apparatus is signed L. E. Knott Apparatus Co., Boston, and also includes a DC bi-polar dynamo electric motor, the K & D No. 2 Porter Motor. This little laboratory demonstration system is operated by turning a small hand crank. The crank turns a large pulley which imparts its rotary motion to a small pulley on the Porter dynamo at a ratio of 13:1. There are two movable copper commutator contacts that can be positioned into four different brass socket locations to change wiring configurations. The apparatus is 8.0" by 13.5" with an overall height of 9.0 inches. This item is well presented on a beautiful aged mahogany base, a very fine display of early electric technology.