  We take the vertical distribution of the radial and azimuthal velocity into
account in spherical coordinates, and find that the analytic relation
c_{s0}/(v_K \Theta) = [(\gamma -1)/(2\gamma)]^{1/2} is valid for both
geometrically thin and thick accretion flows, where c_{s0} is the sound speed
on the equatorial plane, v_K is the Keplerian velocity, \Theta is the
half-opening angle of the flow, and \gamma is the adiabatic index.
