Of the many books that discuss dispersion phenomena, Mr. Beychok's book offers easy to understand explanations of very complex phenomena. The book is well organized. It starts from basic fundamentals and takes the reader through the different aspects of dispersion phenomena and related topics. As part of my career, I sometimes need to conduct gas dispersion modeling to solve accidental release problems. For gaussian dispersion modelling, I have found that the formulations in this book easy to understand and easy to use. I could put them in a spreadsheet software and perform the needed analysis. The book has practically all of the data that a user needs to get started and get to results. I recommend this book to all engineers who have an interest in gas dispersion modeling regardless of their experience level in performing such calculations.