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A theory of double radio sources which have a '2' or 'S' morphology is proposed, based on the refraction of radio jets in the extended atmosphere of an elliptical galaxy. The model describes a collimated Jet of supersonic material bending self-consistently under the influence of external static pressure gradients. Gravity and magnetic fields are neglected in the simplest case except insofar as they determine the static pressure distribution. The calculation is a straightforward extension of the method used by Begelman, Rees, and Blandford (1979) to calculate P. ram-pressure model for twin radio trails ('C' morphology). It may al;o be described as a continuous-jet version of the buoyancy model proposed by Gull and Northover (1973). The model should be particularly relevant to S-shaped radio sources identified with isolated galaxies (such as 30293), whose radio structures should be free of distortions resulting from motion relative to a cluster medium. One might expect it also to apply to 'internal' (dominated by the galaxy rather than the environment) small-scale S-shaped sources such as the inner jet structure of Fornax A. Finally, giant cD galaxies near the center of clusters which display 'C'-shaped morphologies may also fit this description (e.g., 1919 + 479). The model has the added virtue of invoking a galactic atmosphere similar to those already indicated (1) by x-ray measurements of some other radio galaxies (Fabricant et al., 1978) and (2) by models for the collimation of other radio jets (Chan and Henriksen, 1980; Bridle, Chan, and Henriksen, 1981).