Wiiliam Hardy patented this in 1880. It appears to be a spring-loaded reel seat.
As the photos show it was found in/on the handle of a greenheart fly rod (partial!).
I have not seen one before so both I and the owner would love to know if the TFF know more about it or have other examples.
![Image](https://i.imgur.com/wcMYYkW.jpg)
![Image](https://i.imgur.com/3n4akzY.jpg)
![Image](https://i.imgur.com/JGopTRp.jpg)
![Image](https://i.imgur.com/VAdbDDy.jpg)
![Image](https://i.imgur.com/UAGNl8m.jpg)