  A new model for cosmic strings (i.e. conical singularities) attached to black
holes is proposed. These string are obtained by a explicit construction via
limiting process from the so-called Bonnor rocket. This reveals quite
surprising nature of their stress-energy tensor which contains first derivative
of Dirac $\delta$ distribution. Starting from the Bonnor rocket we explicitly
construct the Schwarzschild solution witch conical singularity and the
C-metric. In the latter case we show that there is a momentum flux through the
cosmic string, causing the acceleration of the black hole and the amount of
this momentum is in agreement with the momentum taken away by gravitational
radiation.
