Round, medium indelible lead, smooth core. The copying pencil is a form of indelible pencil with an aniline dye embedded in the lead.
An indelible pencil cannot be erased. They were introduced in the early 1800's to enable documents with a sense of permanence to be produced.
Prior to their introduction these documents had to be written with fountain or quill pens which were expensive and awkward to use.
