These are most likely for holding candle sticks that would fit on the extended brackets. I have two pianos in my shop that have candle holders built into the front board. I have another with a slot in the left key block that has a metal plate around the slot. It looks like it could take a silver dollar, but there is no coin box. It must have had a flat stick that fit in the slot to support a candle holder. All these pianos were from pre-electric days. 1870 to 1910. Douglas Gregg Classic Piano Doc Southold, NY 11971
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