Lab measurement of physical rock properties, such as seismic compressional and shear velocities, can be an important link between in situ measurements of borehole lithology and the information content in remotely sensed surface seismic data. We made lab measurements of elastic velocities and in dry and saturated Massillon Sandstone rock samples. The rock samples were placed under a uniaxial force of 100 lb distributed over the core sample end surface area. ¶ and § pulsed waves were transmitted through the rock sample and first-break arrival times were picked from ¶ and §-mode waveforms. The first-break analysis gives dry rock ¶ and § wave velocities of dry = 2918 32 m/s and dry = 1731 99 m/s, and water-saturated rock velocities of wet = 3380 78 m/s and wet = 1744 201 m/s, respectively. We also tested Gassmann's prediction of saturated velocity from the dry rock measurements, and found that Gassmann's relation gave incorrect and potentially misleading results, on the order of 20% less than lab measured saturated velocities.