That is a beautiful clock. Synchronous electric wall clocks were commonplace here in Australia prior to the 1980's when battery powered quartz movements came in. I have a number of school style clocks like your Cincinnati, but mine are Smiths, Simplex and Metamec branded. I do have a rare Smiths school clock, Australian made from the 1970's, with a 'tuning fork' movement powered by a single 'C' sized battery. My others clocks are all synchronous AC (240V 50Hz here in Australia). Great topic!

Heres mine. A smiths 1960s electric clock . Its s great little clock this one. Its silent too. There was one in my old primary (elementary) school that got me wanting one. Im also after another for the back bedroom! This one i got off ebay the guy said it wasnt working. I plugged it in and it worrked great!