One instrument made by Bradbury in the 1890s had a spun over rim with large independent tonering which fited over the rim.
Prior to 1920 the firm of Kohler & Chase of San Francisco had made for them an instrument similar to a banjo which they called the “Bradbury patent”.
The instrument was designed on the Zither banjo principle with an 8 ½” velum housed in an enclosed bowl type hoop .. but it had 10 strings (5 pairs?) and the scale length was the same as the banjo but no indication is known of the tuning of this instrument. It appears this instrument was discontinued in 1922.
Do you have a banjo by this maker? can you supply us some images?