statutes on the power intensities at which they can be applied severely limit the temperature rises obtainable in practice. Certainly, in treating hands, muscles, ankles, and conditions relatively near the skin, appre-ciably higher in vivo temperatures can be achieved using superficial heating modalities (Figs. 2-5). Fur-thermore, inasmuch as the superficial modalities treat a larger area of the body than deep heat modalities do, the total amount of heat absorbed (which is proportional to the total body area exposed to the heat source) will be much higher. In hand treatment, for example, if ultrasonics and paraffin were capable of identical in vivo temperature elevations, the patient receiving paraffin treatment would receive 30 times more heat because his entire hand is being heated, not just the 15 or so square centimeters under the ultrasound head.