Wow! Antique-shop.com forums are in the big #1 spot on Google for the search term "antique shop forum", for 4 years running!Thanks to YOU.
Actually, it's the valve trigger for a Starline Cattle Drinking Fountain.(Now...you didn't think I was that smart all by myself did you? )http://www.ebay.com/itm/Antique-Cast-Iron-Starline-Cow-Water-Bowl-Waterer-Watering-Livestock-Cattle-Dish-/260896100172