One of the most prolific applied mathematicians of the mid-twentieth century, Prof Lin is a highly respected professor at MIT. These volumes, a collection of Prof Lin's papers from 1943 to 1986, is an attempt to exhibit a historical perception of the development of ideas in the following areas of research:Stability of Parallel FlowsTurbulenceSpiral Structure of GalaxiesProf Lin has written short comments and personal recollections on the development of thinking in these subjects. In addition to research papers, there are two essays dealing with the basic thinking that underlies the development of applied mathematics as an academic discipline in USA. Other topics of interest are Aerodynamics, Liquid Helium, Solid State Physics, Plasticity and Magnetohydrodynamics. About 51 papers are included in these two volumes.