I have chosen to make all these comparisons by reference to the ships' logs, and to give results such as a shipowner looks for rather than those which engineers prefer to use in forming a judgment on the merits of different engines. I do this for two reasons: first, because the commercial success of the triple compound engine depends on the saving it can effect in a long voyage; and secondly, because I had no reliable indicator diagrams from which the consumption per indicated horse power could be calculated with any degree of accuracy. On trial trips with the steamers already named, the consumption of ordinary South Yorkshire coal was 1.6 lb. per indicated horse power, and the consumption of water per indicated horse power calculated from the high pressure indicator diagrams was 1.41 in the Draco, 13.2 in the Rosario, and 13.16 with the Finland, or taking the medium pressure diagrams, it was 12.2, 1.30, and 11.95 respectively. Twelve months ago we constructed for Messrs. Thomas Wilson, Sons & Co., two sets of triple expansion engines of 600 indicated horse power, one having two cranks and the other three cranks, the engines, boilers, and propellers being otherwise exactly alike and fitted into sister ships. The water consumed in the three crank engine is 12.93 lb., against 13.0 in the two crank, but the former drives its ship nearly ½ knot per hour faster than the latter does its, and when both ships are driven at the same speed the consumption of coal in the three crank ship is considerably less than in the other.