838 REPORT—1899. 
Steamship design to be successful must always be based on experiment and 
experience as well as on scientific principles and processes. It involves problems 
of endless variety and great complexity. The services to be performed by steam- 
ships differ in character, and demand the production of many distinct types of 
ships and propelling apparatus. In all these types, however, there is one common 
requirement—the attainment of a specified speed. And in all types there has been 
a continuous demand for higher speed. 
Stated broadly, the task set before the naval architect in the design of any 
steamship is to fulfil certain conditions of speed in a ship which shall not merely 
carry fuel sufficient to traverse a specified distance at that speed, but which shall 
carry a specified load on a limited draught of water. Speed, load, power, and fuel 
supply are all related; the two last have to be determined in each case. In 
some instances other limiting conditions are imposed affecting length, breadth, or 
depth. In all cases there are three separate efficiencies to be considered: those of 
the ship, as influenced by her form; of the propelling apparatus, including the 
generation of steam in the boilers and its utilisation in the engines; and of the 
propellers. Besides these considerations, the designer has to take account of the 
materials and structural arrangements which will best secure the association of 
lightness with strength in the hull of the vessel. He must select those types of 
engines and boilers best adapted for the service proposed. Here the choice must 
be influenced by the length of the voyage, as well as the exposure it may involve 
to storm and stress. Obviously the conditions to be fulfilled in an ocean-going 
passenger steamer of the highest speed, and in a cross-Channel steamer designed 
to make short runs at high speed in comparatively sheltered waters, must be 
radically different. And so must be the conditions in a swift sea-going cruiser of 
large size and great coal endurance, from those best adapted for a torpedo boat or 
destroyer. There is, in fact, no general rule applicable to all classes of steamships : 
each must be considered and dealt with independently, in the light of the latest 
experience and improvements. For merchant ships there is always the commercial 
consideration— Will it pay? For warships there is the corresponding inquiry— 
Will the cost be justified by the fighting power and efficiency F 
. 
Characteristics of Progress in Steam Navigation. 
Looking at the results so far attained, it may be said that progress in steam 
navigation has been marked by the following characteristics :— 
1. Growth in dimensions and weights of ships, and large increase in engine- 
power, as speeds have been raised. 
2. Improvements in marine engineering accompanying increase of steam 
pressure. Economy of fuel and reduction in the weight of propelling apparatus 
in proportion to the power developed. 
3. Improvements in the materials used in shipbuilding; better structural 
arrangements ; relatively lighter hulls and larger carrying power. 
4, Improvements in form, leading to diminished resistance and economy of 
power expended in propulsion. 
These general statements represent well-known facts—so familiar, indeed, that 
their full significance is often overlooked. It would be easy to multiply illustra- 
tions, but only a few representative cases will be taken. 
Transatlantic Passenger Steamers. 
The Transatlantic service naturally comes first. It is a simple case, in that 
the distance to be covered has remained practically the same, and that for most of 
the swift passenger steamers cargo-carrying capacity is not a very important factor 
in the design. 
In 1840 the Cunard steamship Britannia, built of wood, propelled by paddle- 
wheels, maintained a sea-speed of about 84 knots. Hersteam pressure was 12 lbs. 
per square inch. She was 207 feet long, about 2,000 tons in displacement, her 
