Found this: http://www.chinet.com/~plaws/GovtBridge-RI.jpg
It appears to be an artist's work sometime after the bridge was built and prior to lock and dam 15 being built underneath it. The bridge was completed in the late 1890's. The lock and dam was installed sometime in the 1930's.
At the very top of the bridge you can see the line wires and cross arms. Directly below is the 'turn pile' or what we now call a commutator. This is the feature that allows this type of bridge to do 360 degree turns. It can lock up in either direction. I've been told there only a handful of bridges in the entire world that can still do this.
I was inspecting the 'lever interlocker' in the control house a few days ago. One of the USS levers had an original mfg. stickers in it.......Nov. 13, 1903. And it's still working!!!!
PS....If you would like a copy of the signal plans (circa 1954) for this bridge, PM me. Only the cost of copying and postage. It's about six feet long.