They are Ford style Model T ignition coil boxes, or buzz boxes as they are usually referred to. They contain the ignition coils and condenser for one cylinder and the Model T cars used four of these buzz boxes. On top of the box are the exposed points which buzzed during operation. These boxes need a separate power supply, like a 6 volt battery, to operate.
On an outboard motor, they can be used to replace a faulty magneto system. Here’s some more information explaining how to check and repair them:
http://members.iinet.net.au/~cool386/fo … coils.html