The spread of the habit of sea trade from the Mediterranean to North-west Europe led to changes in the design and construction of ships. By the middle of the seventeenth century old difficulties about disease due to stinking bilge-water had largely been overcome, and ships were being built with better proportions for speed and manoeuvring, and in the early eighteenth century came the full adaptation of the fore-and-aft sail and the use of mahogany and other hard woods from the tropics for ship furniture, and so for house furniture too. With all this went increased size and speed of ships and ability to tack effectively, and so, broadly, to follow a course even if winds were variable. With all this new power and also the development of armaments, Europe found herself in a position to exploit the other parts of the earth inhabited by other races less well equipped. They gradually, nay almost suddenly, became the producers of raw materials, food-stuffs, and fertilizers for the vastly increasing populations of industrial Europe, which began to teem in the manufacturing cities when coal and steam machinery were added to the European equipment. Along with this industrial development has gone the nationalist revival to which reference has already been made in several places (pp. 23, 33, 35, 49, 62-3), a cultural movement which in the nineteenth century became politically embittered, and which through its imperialistic outgrowths in England, Germany, France, and Russia has been a main factor of the recent war. {99} 10 _Aspects of Modern Europe_