Generations of graduate students (including the present reviewer) were brought up on earlier editions of Guy White's book, which for years remained the only available supplement to the unwritten body of lore handed down by one's predecessors and supervisor and colleagues. It is a detailed exposition of the how of experimental physics at low temperatures: how to attain the low temperature, and how to measure it when you have got it; not only how to set about designing cryogenic apparatus, but also how to translate the design into a functioning and (one hoped) leakless reality. The third edition has been reworked more thoroughly than its predecessor, and is the better for it. Some of the less used sections have been pruned to make way for new materual reflecting the growing emphasis on work below I K, and the whole book has generaIly been brought up to date.