WRITING WITH SPARKS
In 1875, Thomas Edison invented a device called the electric pen. He designed the pen for writing words — in the form of fine holes — quickly and easily on special paper. The paper thus became a stencil.Placing the stencil on a clean sheet of paper and then running an inked roller over the stencil produced a copy of the written words. The stencil could be used about 5000 times. This early idea of Edison’s gave birth to a basic office machine, his Mimeograph, that in modern form is still used today for reproducing letters and similar matter. The electric pencil you are going to make is a cousin to Edison’s pen. Instead of making holes in the paper, however, the electric pencil sparks a trail on metal. But being such a simple instrument, it will work only on soft metal.
    
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