  Estimates of orbital parameters were made using a Bayesian optimization
technique on astrometric data for 25 visual binary systems catalogued a century
ago by the ninth Astronomer Royal, Sir Frank Dyson. An advantage of this method
is that it provides reliable, unbiased uncertainty estimates for the optimized
parameters. Reasonable agreement is found for the short period (< 100 yr)
systems between the current study and Dyson, with superior estimation for the
longer systems through the inclusion of an additional century of data.
Dynamical masses are presented for the systems through the inclusion of
parallax measurements.
