• The early 19th century had its own version of today's dark matter problem: the planet Uranus was drifting off course. The mystery was solved in 1846, when observers, guided by theorists, discovered Neptune. Its gravity could account for Uranus's wayward orbit.
  • Historians have traditionally apportioned credit between a French theorist, Urbain Jean Joseph Le Verrier, and an English one, John Couch Adams. Le Verrier's role is undisputed, and so was Adams's--until the mid-20th century.
  • Just as more historians were beginning to reexamine Adams's role, a sheaf of crucial documents went missing from a British archive. It surfaced in Chile in 1998. The authors came across other crucial documents this past summer.
  • The bottom line is that Adams did some interesting calculations but deserves no credit for the discovery.