Hood firearms company
Well, with the help of my buddy Ben Hale, it looks like the mystery is solved.
While some major manufacturers like Colt and Smith & Wesson made similar designs with minor differences in appearance and function...and others like Iver Johnson, Whitney Arms, Merwin Hubert, and Hopkins & Allen went with their own similar designs and clones, a lone gentlemen by the name of
Freeman W. Hood was the designer of the Centennial pistol I now own.
His design ( Patent #160,192 ) was approved on February 23rd, 1875, and the blueprints and patent claim below are proof positive that his Hood Firearms Company design was showcased at the Philadelphia Centennial World Expo of 1876. He went on to make minor changes in this design in later months/years...then he was soon lost in the annuals of history.