Thsi thing is from Amherst's Archives and Special Collections. No one there knows what it's purpose is, and they are asking for readers to help. (I'll bet Boing Boing's readers will come up with the answer today.)
The device is about 12 inches across and is seen here sitting on its flat wooden platform; apparently, it would be removed from the platform for use. The raised lid has a clip that restrains a spring-loaded brass oval, here shown released and resting on top of a ring of brass arms. Each brass arm has at its narrow end a sharp, upward-facing point. Those points form the innermost oval. The arms are connected to padded, movable wooden rods hanging below the device.
Mel Johnson sez: I believe I know what this device is.
In fact, as a child I had my head inside one, in the old McFarlin's Men's Clothing Store in Rochester, New York.
A piece of paper is fastened in the top of the device – probably held by the thee pins nearest the center. Then the device is placed over someones head, with the padded rods over and around the head, so the rods cushion the outer circumference of
the head, the flat surfaces of the device being parallel to the floor. Something happens with the piece of paper such that an outline of the head is punched in the paper with the pointed rods, giving the shape of the head.
It was used in clothing stores to aid in fitting hats.
My head was pear-shaped!
Anne sez: Here's some confirmation of the hat-fitting hypothesis: a picture of a similar hat-fitting device, a "conformateur", apparently patented in the 1850s by one Monsieur Maillard. It's shown on the head. Antiques like this are apparently still used in hat-making today, because no-one is manufacturing new ones. Link