  We present the results of measurements of the thermal and electrical
conductivity in the basal plane of single-crystalline MgB_2 between 2 and 300
K. The analysis of the temperature dependence of the thermal conductivity gives
supporting evidence for two different gaps on different sheets of the Fermi
surface in the superconducting state. The zero-temperature values of the two
gaps are D_1 (0) = 5.3 meV and D_2 (0) = 1.65 meV.
