Thank you. For clarity, here is my edited comments. I made a few typos. :)
This patent mark seems to relate to a sliding mechanism within the table hardware. I find that it is a mark from the Perfection Table Slide Mechanism Co. of Watertown, Wisconsin. The mark is nice however as it does date your table and places it in the realm of Colonial Revival pieces...as does the construction and way the legs collapse together. This is a 20th century innovation to the style.
These large Duncan Phyfe style dining or banquet tables do have value but their condition is important as they are not rare and the market is soft right now on furniture. A table with its brass claw feet and the traditional pedestal construction (not this Warfield style)even in a revival period table has a value in in the range of 450.00-600.00. Examples of this style table, and this patented construction, that have sold in the last 7 years show to have a value in the range of 125.00-150.00.
Please note, in case this was less than you expected, that true early period Duncan Phyfe tables on the fine antique market, in good condition, are selling for c.1200.00... so we are not talking grave distances in value. It is that tables such as these are not selling for what they are worth the last decade throughout. It is a pity.
I hope this is helpful. Certainly a local sale would be more kind to an appealing and useful table of this type but knowing the market and what it will bare is good to know if the piece does not sell for what you want initially.
Best wishes, Dori
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