The considerations that inspired the builders to design the Titanic on the lines on which she was constructed were those of speed, weight of displacement, passenger and cargo accommodation. High speed is very expensive, because the initial cost of the necessary powerful machinery is enormous, the running expenses entailed very heavy, and passenger and cargo accommodation have to be fined down to make the resistance through the water as little as possible and to keep the weight down. An increase in size brings a builder at once into conflict with the question of dock and harbour accommodation at the ports she will touch: if her total displacement is very great while the lines are kept slender for speed, the draught limit may be exceeded. The Titanic, therefore, was built on broader lines than the ocean racers, increasing the total displacement; but because of the broader build, she was able to keep within the draught limit at each port she visited. At the same time she was able to accommodate more passengers and cargo, and thereby increase largely her earning capacity. A comparison between the Mauretania and the Titanic illustrates the difference in these respects:-- Displacement Horse power Speed in knots Mauretania 44,640 70,000 26 Titanic 60,000 46,000 21 The vessel when completed was 883 feet long, 92 1/2 feet broad; her height from keel to bridge was 104 feet. She had 8 steel decks, a cellular double bottom, 5 1/4 feet through (the inner and outer "skins" so-called), and with bilge keels projecting 2 feet for 300 feet of her length amidships. These latter were intended to lessen the tendency to roll in a sea; they no doubt did so very well, but, as it happened, they proved to be a weakness, for this was the first portion of the ship touched by the iceberg and it has been suggested that the keels were forced inwards by the collision and made the work of smashing in the two "skins" a more simple matter. Not that the final result would have been any different. Her machinery was an expression of the latest progress in marine engineering, being a combination of reciprocating engines with Parsons's low-pressure turbine engine,--a combination which gives increased power with the same steam consumption, an advance on the use of reciprocating engines alone. The reciprocating engines drove the wing-propellers and the turbine a mid-propeller, making her a triple-screw vessel. To drive these engines she had 29 enormous boilers and 159 furnaces. Three elliptical funnels, 24 feet 6 inches in the widest diameter, took away smoke and water gases; the fourth one was a dummy for ventilation.