The paper deals only with the supply, of power for the auxiliaries of a modern power station, no attempt being made to discuss the relative merits of apparatus such as evaporators, ejectors, etc.The following aspects of the problem are dealt with :—(1) Consideration of the different types of auxiliaries used in a station.(2) Consideration of the different types of supplies available.(3) Suitability of different auxiliaries and supplies for various conditions of station working.Seven alternative schemes for the supply to the auxiliaries of a proposed new station are described and tabulated, and the advantages and disadvantages of each are considered in turn.Certain of these are recommended by the authors, this recommendation being based on the principle that no expense should be spared to secure a simple and reliable system of station auxiliaries.Some observations are made on features to be taken care of when auxiliary supplies are being laid down.