They've been around for quite some time, Ron.  Carbon arc lamps use them.
Because use involves arcing current between two of them, they degrade (I
forget whether the + or - pole degrades faster), and are usually easily
replaceable elements of the lamp. The Parks Canada lighting devices book
discusses them, and may have dates.

The ones I've seen appeared to be molded.

-----Original Message-----
From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]]On Behalf Of Ron
May
Sent: Friday, October 28, 2005 3:03 AM
To: [log in to unmask]
Subject: Re: Old Flashlight batteries


Archaeological investigations of a burned 1916-1919 United States Army
building at Fort Rosecrans, San Diego, California (CA-SDI-12,000) exposed a
number
of carbon rods of various sizes. Although some were undoubtedly from
batteries, other larger ones were associated with search lights used for
coast
artillery sighting. I too have wondered how those were made and how long the
technology has been around.

Ron May
Legacy 106, Inc.