  In the model-independent approach consisting in the immediate application to
the analysis of experimental data of such general principles as analyticity and
unitarity, a confirmation of the $\sigma$-meson at $\sim$ 665 MeV and an
indication for the glueball nature of the $f_0(1500)$ state are obtained on the
basis of a simultaneous description of the isoscalar s-wave channel of the
$\pi\pi$ scattering (from the threshold up to 1.9 GeV) and of the $\pi\pi\to
K\bar{K}$ process (from the threshold to $\sim$ 1.4 GeV where the 2-channel
unitarity is valid). A parameterless description of the $\pi\pi$ background is
first given by allowance for the left-hand branch-point in the proper
uniformizing variable. It is shown that the large $\pi\pi$-background, usually
obtained, combines, in reality, the influence of the left-hand branch-point and
the contribution of a very wide resonance at $\sim$ 665 MeV. The coupling
constants of the observed states with the $\pi\pi$ and $K\bar{K}$ systems and
lengths of the $\pi\pi$ and $K\bar{K}$ scattering are obtained.
