The fret markings clearly are a major feature of the claims. He states:
"In a stringed instrument, the combination, with the sounding board or base, of the separate parallel longitudinal bridge-bars, each having a group of four strings, a line of line of frets, and note-scales , and having the keys for the strings at one end of each bridge-bar set at the opposite ends of the sounding-board, substantially as herein set forth."
The drawing almost certainly has shape notes because he says:
"The note-scales may be made in characters such as are found in the “Sacred Harp” and in the “Temple Harp,” or indicated by do, re, mi, &c."
Actually, on close reading, it looks like it may only apply to the combination of the features, not to any on them singularly. Not to worry, it expired long ago. .
There are many patents for specific instrument designs which are more-or-less actually sort of trademarks. This is particularly true on "anyone-can-play-this" instruments.
I find the patent interesting because it reinforces our knowledge of many features as being broadly* known by 1880.
- Four string designs
- Rectangular sound boxes
- Fret labels
- Zither/piano pin tuners
- Wire strings
*The patentee resided in the flat Mid-Georgia country, not in the hills of KY-NC-WV-VA