A summary of A F Yarrow's paper read to the Institution of Naval Architects in 1883. Yarrow described a series of experiments in which he had tried to ascertain the indicated power of the engines and the thrust on the shaft of a first-class torpedo boat when steaming under its own power and also the power required to tow the boat. The full text of Yarrow's paper and the discussion that followed was published in the Transactions of the Institution of Naval Architects, vol. 24, 1883, pp. 111-117.