Harmony Disc Records were produced by Great Northern Mfg. Co. located on 147-153 Fifth Avenue, Chicago. The company was established in 1907, though according to the information provided on labels, the first patent was registered Dec 10, 1901. In order to avoid problems with «Victor» and «Columbia» they used oversized centre-holes. They said, that the records would only be possible to play on Harmony's own machines, though it is not a problem to play them on any standard player using special adapter just like 45 rpm adapter but with smaller outer size, or even without it. (I have no problems playing these records on my turntable without any adapter). Apparently this trick worked fine, because they were able to obtain stock from «Columbia» with agreement to drill out centre-holes to 3/4 inches wide and to use just plain pasteover labels. In 1916, the label merged with Consolidated Talking Machine Co.