This century old authentic Dynamo Electric Machine is in perfect working condition. Crank the handle at about 25 rpm and the little Edison type light bulb glows with a remarkable yellow light. The light intensity varies with crank speed. It is a great way to teach the next generation of little Edison inventors about how electricity is made and works. The dynamo is mounted on a ripe old 6.5" by 7.5" oak base. The overall height is 11.5" with a crank gear diameter of 9 inches. The fabulous little bulb has a huge three quarter inch globe which is mounted in a miniature porcelain light socket.