The launching of ultrasonic shear waves generated by a crystal transducer into a solid medium is discussed, and the method whereby the transverse oscillations are coupled from the transducer to the medium by the application of a steady mechanical pressure is more particularly examined. The mechanical design of a single-crystal transducer, and of a four-crystal transducer which enables perpendicular planes of polarization to be readily selected, is discussed, together with methods of applying the steady pressure (which is typically about 20,000 lb/in 2). The design of a shear wedge which permits the axis of polarization of a transducer to be readily determined is also given.