*Preliminary report on certain investigations now in progress at the Massachusetts Institute of Technology. The first synoptic analyses of isentropic flow patterns by the method described below were carried out by D. P. Keily, J. W. W. Osmun and J. Namias in cooperation with the author. Isentropic charts are now analyzed daily under the direction of J. Namias and H. C. Willett. Model experiments for the study of current patterns in rotating systems are conducted by A. F. Spilhaus with the aid of a grant from the Woods Hole Oceanographic Institution. The theoretical investigation of the effects of isentropic mixing was initiated by the author and is now continued by J. Holmboe, G. Grimminger and others.