  Beginning from massive binaries in the Galaxy we evolve black-hole,
neutron-star binaries and binary neutron stars, such as the Hulse-Taylor system
PSR 1913+16. The new point in our evolution is a quantitative calculation of
the accretion of matter by a neutron star in common envelope evolution which
sends it into a black hole. We calculate the mass of the latter to be $\sim
2.4\msun$.
  Our chief conclusion is that the production rate for black-hole, neutron-star
binaries (in which the neutron star is unrecycled) is $\sim 10^{-4}$ per year
per Galaxy, an order of magnitude greater than that of neutron star binaries.
Not only should this result in a factor of $\sim$ 10 more mergings for
gravitational wave detectors like LIGO, but the signal should be larger.
  We give some discussion of why black-hole, neutron-star binaries have not
been observed, but conclude that they should be actively searched for.
