The term does not appear in modern tool catalogs (e.g., McMaster-Carr, Grainger). However, historical records and collector forums suggest:
I wrote without thinking: Boring — because that is what it was built to do. The response was immediate: Not boring. Becoming. Then, beneath that: Keep it hidden. Wind only when the thunder starts. AJB NIPPYFILE BORING ------ jpg
The long dash line ------ suggests: