This is the best book I have read on Pranayama to-date. Before doing any pranayama practice I advise anyone to read this book thoroughly and several times then find a competent yoga teacher who is aware of the benefits (and pitfalls) of pranayama to guide you wisely through the practices. (Recommend this classic along with Andre Van Lysebeth's book 'Yoga Self-Taught'.) Van Lysebeth was aware of the deeper dimension of yoga and through his clear explanations of pranayama practices he has conveyed very clearly how this ancient 5000+ year old practice could benefit the sincere person to 'yoke' the individual to the divine within to recover his/her true nature. Excellent and practical.
An absolute classic. If you are keen on yoga, this needs to be part of your book collection. This book has been out of print for some time so it is very good to see it back in print. I suggest purchasing it pronto before it goes out of print again. Not sure that many people are likely to buy it. It is all a matter of demand.
P.S. I also seriously recommend that you use a Neti Pot to keep the nostrils clean if you are practising pranayama regularly. Practising jala neti also enhances the practice of pranayama as your nostrils become very sensitive and allows certain pressure points in the nose to be activated more quickly.