  We have investigated uniaxial and hydrostatic pressure effects on
superconductivity in Fe1.07Te0.88S0.12 through magnetic-susceptibility
measurements down to 1.8 K. The superconducting transition temperature Tc is
enhanced by out-of-plane pressure (uniaxial pressure along the c-axis); the
onset temperature of the superconductivity reaches 11.8 K at 0.4 GPa. In
contrast, Tc is reduced by in-plane pressure (uniaxial pressure along the
ab-plane) and hydrostatic pressure. Taking into account these results, it is
inferred that the superconductivity of Fe1+yTe1-xSx is enhanced when the
lattice constant c considerably shrinks. This implies that the relationship
between Tc and the anion height for Fe1+yTe1-xSx is similar to that applicable
to most iron-based superconductors. We consider the reduction of Tc by
hydrostatic pressure due to suppression of spin fluctuations because the system
moves away from antiferromagnetic ordering, and the enhancement of Tc by
out-of-plane pressure due to the anion height effect on Tc.
