I get a lot of history questions here at Sparkletack — some I can handle, but others stump me completely.

A few weeks ago, a longtime listener named Demetrios hit me with one of those stumpers:

bush-and-montgomery“This is regarding the Sparkletack posting I sent you with regards to the letters ‘E’ that I keep seeing everywhere engraved on granite curbs in the Financial District (mostly).”

This is driving me nuts! I have noticed the letter ‘T’ on occasion as well, but by far the letter ‘E’ is the most common letter haunting my walks around the Financial District.

The letter “E” and the letter “T”.

Straightforward question, right? And so I tried to figure it out. I looked in the usual locations, posted the question on some other San Francisco history websites, even (because my first guess was “quarry mark”) tracked down the quarry which had supplied those granite curbs to the City after the ’06 quake …

Nothing. Weeks went by.

And then, out of the blue, an email dropped into my inbox from one Peri Cosseboom.

Peri Cosseboom is a San Francisco history buff focused on surveying and land development. He’s a San Francisco native, raised in the Mission and Tenderloin, married to a native of Chinatown, and even speaks with that elusive “south of the slot” San Francisco accent. Now those are what I call credentials!

His generous explanation prompted an immediate slap to my forehead.

Aargh, it was SO obvious …

The “E”, “T” and on curbs downtown represent the approximate point where underground electrical and telephone ducts crossed the cubline and entered the building that they served. “WU” represented Western Union” telegraph crossings but are quite rare. My recollection is that Western Union maintained active overhead lines downtown until the early 80′s. “G” represents gas lines, but is also uncommon.

These marks date back to just after the ’06 quake when undergrounding electrical and telephone lines was uncommon and having marks of this sort to indicate the point of service was useful.

The “T” & E” marks when found on the curved parts of curbs at street intersections (curb returns) do not represent crossings, but are reference points for the location of telephone/electrical manholes. The company involved would measure from 2 of these marks (on opposite curbs) to a manhole. Crossing 2 tapes at the recorded measurements would locate a buried manhole. These record measurements are now also obsolete.

These marks are also found in subdivisions created just after WW1, (e.g.. Forrest Hills) where the utilities were undergrounded for aesthetic reasons. The practice was discontinued soon thereafter when utility undergrounding became more common and when infrastructure records became more accurate.

“W” & “S” are found everywhere in the City, representing water line and sewer lateral crossings. The “S” is most commonly found on the “armored curbs” constructed in the neighborhoods by the WPA during the depression, but they can occur anywhere. The “W” seems to only appear on granite curbs and thus predate about 1930. Again, accurate infrastructure mapping made their use obsolete.

Thanks, Peri — curiousity satisfied, and how!