Thanks for the link Rod, would never have guessed that there was so much info out there.
About what I had guessed, the trolley flanges ride the slightly lower RR rail head. One fact that I didn't see noted but may have been as I didn't read all the ''fine print' I was falling asleep-- is that trolley flanges are as not as ''tall'' as RR ones. Trolley height is 5/8 to 3/4'', depending on the system, and there is no danger of the depth of the SEPTA cars being built to RR wheel standards to run on CSX track because the gage is different (5'-2½'')
Thanks to all, your checks are in the mail.
____________________ Fix it again, Mr Gates--it still works!"
The oldest preserved measuring rod is a copper-alloy bar that dates from c. 2650 BC and was found by the German Assyriologist Eckhard Unger while excavating at Nippur.
Ludwig Wittgenstein famously used rulers as an example in his discussion of language games in the Philosophical Investigations.
He pointed out that the standard meter bar in Paris was the criterion against which all other rulers were determined to be one meter long, but that there was no analytical way to demonstrate that the standard meter bar itself was one meter long.
It could only be asserted as one meter as part of a language game.
Anton Ullrich invented the folding ruler in 1851.
Historically, a flexible lead rule used by masons that could be bent to the curves of a molding was known as a lesbian rule.