Other than the one in our collection, we are aware of only two others. One is in the Smithsonian collection in Washington, DC; however, it is not on display. We have examined pictures of it and while it is very similar to the one in our collection, it is not identical.
The second is in the US Naval Academy Museum in Annapolis.
If you know of any other examples of the the Time of Flight Clock, please leave us a note.
We have a partial record of a possible fourth Time of Flight Clock that was sold at auction in Connecticut in 2016 but there was no description or pictures so we do not know if it was a Mark 1 or a later model or something else altogether.