Here is a unique insulator go-with!! The Calculagraph was initially patented May 25, 1897 and mechanically calculates and prints the elapsed time between two events. Their best known, earliest use was as a means of tracking of table usage in pool halls and then they became the standard way to clock the duration of toll telephone calls. This version appears complete and comes with it's original manual and additional documentation. $75 plus actual postage.

Also included is a special history of these tools.

NOTE: I'm selling these items & insulators on behalf of the Jim Fielding estate -- PayPal (no fee friends and family) or checks are both accepted - I'll provide instructions. I'll also be handling all the packing and mailing.