  Statistics of orbital parameters of binary stars as well as statistics of
their physical characteristics bear traces of star formation history. However,
statistical investigations of binaries are complicated by lacking or incomplete
observational data and by a number of observational selection effects.
  Visual binaries are the most numerous observed binaries, the number of pairs
exceeds 130000. The most complete list of presently known visual binary stars
was compiled by cross-matching objects and combining data of the three largest
catalogues of visual binaries. It was supplemented by the data on parallaxes,
multicolor photometry, spectral characteristics of the stars of this list taken
from other catalogues. This allowed us to compensate partly for the lack of
observational data for these objects. Combined data allowed us to check
validity of observational values and to investigate statistics of the orbital
and physical parameters of visual binaries. Corrections for incompleteness of
observational data are discussed. Obtained datasets and modern distributions of
binary parameters will be used to reconstruct the initial distributions and
parameters of the function of star formation for binary systems.
