Tim Robinson and Richard Horton

Tech millionaire Nathan Myhrvold commissioned London's Science Museum to make him a version of Charles Babbage's famous difference engine, a machine designed to mechanically calculate polynomial functions. (The Science Museum has the only other full-scale difference engine in the world; Babbage himself never actually made one).

Wednesday, the machine Myhrvold commissioned was delivered to the Computer History Museum in Mountain View, Calif., and is scheduled to be exhibited there for six months starting May 10.

Here, Tim Robinson (right), who makes specialized computing machinery, shows his version of a Babbage difference engine to Richard Horton (foreground), the lead engineer on the Myhrvold/Science Museum. Robinson brought his scaled-down model to the Computer History Museum.

This photo gallery has been updated with the correct opening date for the public exhibition. It opens on May 10.