The equations of mean motion for a two dimensional jet deflected by an ambient stream are studied. On condition that the initial velocities of the jet and ambient stream differ not too much in direction and not too little in magnitude, the equations holding in certain regions of the deflected jet flow field are shown to be similar to those for a jet in a coflowing stream. A preliminary study of self preervation is also attempted. Experimental measurements are made to confirm the similarity of the mean velocity field of the two kinds of jet flows. Self preservation of the excessive dynamic pressure is confirmed for the two-dimensional jet. The jet axial location is found to be independent of the jet-to-ambient velocity ratio if all lengths are divided by the squares of that ratio. The initial report is concerned with jet deflection angles of 25 degrees, 17 degrees and 9 degrees. In Appendix 3 mention is made of additional experiments at 45 degrees deflection at which angle some of the conclusions of the initial report are no longer valid.