William J. Thomson emphasizes the formulation of differential equations to describe physical problems, helping readers understand what they are doing -and why. The solutions are either simple (separable, linear second order) or derivable with a differential equation solver. To master this material, readers will only need to know the basics of differential equations, and how to use a differential equation solver such as Matlab, POLYMATH, or ACSL. Thomson begins with a detailed introduction to molecular transport, including the basic underlying laws; one-dimensional molecular energy transport; molecular mass and momentum transport principles; transport coefficients, and similarity analysis. In Part II, he reviews convective transport, presenting a straightforward description of turbulence, and introducing the fundamental concept of transfer coefficients. Building on previous coverage, he then addresses the macroscopic calculation issues associated with momentum, heat, and mass transfer -- enabling readers to solve even complex gas absorption and cooling tower problems.