The general purpose of the work described here is to further develop the understanding of the behavior of high polymers under conditions of dynamic loading. The polymer studied was polyethylene, a viscoelastic solid exhibiting time-dependent effects not found in usual engineering structural materials. A characteristic of these interesting viscoelastic solids is that a stress pulse moving through the medium is both attenuated and spread out in time. For these reasons the material has seen application in the design of shock and vibration isolation mounts. The specific objective of the work described in this thesis was to design and construct apparatus capable of generating and monitoring very short stress pulses in a slender, viscoelastic, cylindrical rod. The apparatus was calibrated and its performance tested. Preliminary data was obtained on viscoelastic rods. The stress pulse was initiated by detonation of explosives at one end of the rod and the corresponding displacement of the other end measured by a variable capacitance transducer. (Author).