  Einstein's blackboard is a well-known exhibit at the History of Science
Museum at Oxford University. However, it is much less well known that the
writing on the board provides a neat summary of a work of historic importance,
Einstein's 1931 model of the expanding universe. As a visual representation of
one of the earliest models of the universe to be proposed in the wake of
Hubble's observations of the nebulae, the blackboard provides an intriguing
snapshot of a key moment in modern astronomy and cosmology. In addition, one
line on the blackboard that is not in Einstein's 1931 paper casts useful light
on some anomalies in the calculations of that paper.
