A system consisting of two rolling transducers, one transmitter and one receiver, is mounted. The active element is a piezoelectric crystal mounted on the central spindle of the rolling transducer, surrounded by castor-oil filled encapsulated in a soft epoxy sheath. This configuration provides a good acoustic coupling between the transducer and the core. A short P-wave pulse is produced at the transmitter at about 230 Kh, that propagates through the cores and is detected by the receiver. The distance traveled is measured as the outside core diameter. A temperature correction is done for the processing of the P-Wave velocities. Using velocity and bulk density it is possible to estimate the acoustic impedance and provide a synthetic seismogram for seismic correlation.