What on Earth are these?????

[thereallyniceman]

Available in 1911 and a snip at  5 shillings.

If I had a Zither banjo I would buy a set :-)

Any ideas on these as I have never heard of them !! ??

[Trapdoor2]

These are early feedback attenuators. Zither-banjos, being what they are, tend to feedback harshly in certain concert halls. The acoustic reflection from the back resonant surface to the rear wall of the hall can escalate exponentially, the results generally being a harsh squeal. In one case, it was documented that the standing wave was causing the conductor's hair to move as if it were inhabited by a drunken stoat.

To avoid such disaster, CE stepped in with a cheap but viable solution, tuned sympathetic springs. One usually selected a spring which produced a minor 5th above the tonic. Hot swappable springs were all the rage prior to the war but wartime spring requirements caused a shortages. Advances in acoustic science allowed concert halls to install cheap ZB dampers and the springs became history...

[Jody Stecher]

These were developed by Vega for the proposed Boing-A-Phone banjo. The prototypes were disappointing and the model never went into production. Vega sold the coils to Clifford Essex at a loss. 

[thereallyniceman]

Makes sense to me !

8-)

[Joel Hooks]

I am going to say that they are alloy testers.  Each spring is a secret Gibson formula of brass.  

There are still people selling magical tone enhancers.  At least this look like something, the ones on the market today are either a folded piece of brass foil or a piece of card stock with some bits of metal taped on.

[Joel Hooks]

Is there any clue how they are fitted?

[Jody Stecher]

How they were fitted?  The right earlobe of the player was pierced as if for earrings. The end of the coil was pushed into the hole and the coil dangled from the lobe. The same was done to one earlobe of each audience member.  It was all the rage. Coil wearers were known as "sproingsters"

[Trapdoor2]

It is a wonder of human intelligence that these were ultimately co-opted for a much more valuable purpose:

[thereallyniceman]

I like your new shoes Marc. When the Mrs said "walk with a spring in your step", I don't think this is quite what she meant. :-)

The puzzle deepens...  more vague instructions:

"Anyone can fix them ...  and they are quite invisible"  ...  Ah Ha,  some sort of cloaking device for banjoists?

[John Cohen]

Oh, I see... You have to pay $1.25 and then they will tell you how they work.

Or maybe the answer can be found somewhere in this video:

https://www.youtube.com/watch?v=le2eB2xtvBQ

[Joel Hooks]

I'm thinking that the ones that did not sell were reused for these...

BTW, as a fan of historical banjo nonsense products I would love to have a set of these springs for a curio box.  It would go great with my Grover Tone Ring, Vibrator, Iucci Tone Ring, and countless mutes including the Hartnett Lever Mute.

[Chris Cioffi]

This must be where Lloyd Loar got his idea for the Gibson Ball Bearing tonering.....

[Joel Hooks]

You win Chris! This is better than I could have ever imagined!! I had an idea that the card fastened into the back inside. I could not have guessed that one was to randomly screw springs to the inside of the rim.