Those recordings, made on aluminum disks, were deposited in the United States National Archives.

In two field expeditions with his young assistant Albert Lord (1912-1991) he would record thousands of songs on aluminum disks.

The park is surrounded by a fence, the eastern edge of which is decorated with small, reflective aluminum disks.

Tom tested the device on several aluminum disks and found that it worked to perfection.

Sandwiched between is a flat aluminum disk.

He stopped the machine, threw the playback switch, set the needle in the outer groove of the aluminum disk, and started it.

It etched the songs of cowboys and former slaves onto aluminum disks, and used two 75-pound batteries for power.

The lightweight bullet was a steel jacketed wooden plug with an aluminum disk protecting the base.

And the shapes imprinted on the aluminum disk look like bones or weights - or feet.

And then it is turned back the other way: through tiny holes in the aluminum disk, we can see the sky outside the gallery window.