  We apply new statistical tests on the four year 53 GHz DMR data and show that
there is significant probability for the existence of coherent temperature
discontinuities hidden in the CMB maps around the Galactic Poles. Comparing
Monte Carlo simulations with the DMR maps we find that the probability for the
existence of a coherent discontinuity with amplitude $0.2 \times ({{\delta T}
\over T})_{rms}$ superposed on the gaussian fluctuations is more than double
than the corresponding probability when no discontinuity is present. This
result is consistent with the existence of a horizon size long cosmic string
with mass per unit length $\mu$ given by $G\mu v_s \gamma_s \simeq 10^{-6}/\pi$
where $v_s$ is the string velocity and $\gamma_s$ is the corresponding Lorentz
factor.
