An analysis of proton-antiproton collisions at s**(1/2) = 1.8 TeV recorded with
the Collider Detector at Fermilab yields sigma(p anti-p --> WX)*B(W --> mu nu) =
2.21+-0.22 nanob and sigma(p anti-p --> ZX)*B(Z --> mu+ mu-) = 0.226+-0.032
nanob.  The ratio is R(mu) = (sigma(W)*B(W --> mu nu))/(sigma(W)*B(Z --> mu+
mu-)) = 9.8+-1.2.  Combining the previous CDF electron results gives sigma(W)*
B(W --> l nu) = 2.20+-0.20 nanob, sigma(Z)*B(Z --> l+ l-) = 0.214+-0.023 nanob,
and R(l) = 10.0+- 0.8.  We extract the ratios of the coupling constants
g(mu)/g(e) and g(tau)/g(mu).  Using Standard Model assumptions we deduce the inverse branching ratio BR**(-1)(W --> l nu), the width Gamma(W), and the decay-
mode-independent lower bound on the top quark mass of 45 GeV/(c**2) (95% CL).