Robertson picked this 1872 model of an electromagnetic engine for its visual appeal. "It reminds me of modern sculptures," he says.

Rothschild Patent Model Collection, Scherzi Photography

A governor for controlling the speed of steam engines.

Rothschild Patent Model Collection, Scherzi Photography

A paper-bag-making machine model submitted by Edgar Stocking.

Rothschild Patent Model Collection, Scherzi Photography

A mousetrap that didn't kill mice but held them captive.

Rothschild Patent Model Collection, Scherzi

A cotton seed planter from 1865.

Rothschild Patent Model Collection, Scherzi

A brick-pressing machine from 1855.

Rothschild Patent Model Collection, Scherzi

An extension ladder from 1878.

Rothschild Patent Model Collection, Scherzi

An artificial leg from 1860.

Rothschild Patent Model Collection, Scherzi