When the author decided to christen his book a ''Pocket Manual'' he was moved to do so by the words of Kent, that ''every engineer should make his own pocketbook.'' Unfortunately not every engineer has the opportunity or ability to gather useful information without paying dearly for it.This ''long-felt want'' is intended to be filled by the ''Pocket Manual,'' a digest of the rules and data of every branch of mechanical refrigeration, embodying the opinions of the foremost men in the field, together with the practical experienceof the author, a receptacle for further research and enlargement, a pocketbook in the very sense of the word, which the author trusts will soon find its way into the pocket of every progressive refrigerating engineer.