The wonderful power and great commercial development is due not only to conditions of geographic environment but also to the intelligence of a people who have adjusted themselves to those conditions. The insular position of the United Kingdom has given it natural protection, and for more than eight hundred years there has been no successful invasion by a foreign power. Its commercial position is both natural and artificial. It has utilized the markets to the east and south, and has founded great countries which it supplies with manufactured products. [Illustration: THE BRITISH EMPIRE] The position of the kingdom with respect to climate is fortunate. The movement of the Gulf Stream on the American coast carries a large volume of water into the latitude of the prevailing westerly winds, and these in turn carry warm water to every part of the coast of the islands. As a result, the harbors of the latter are never obstructed by ice; those of the Labrador coast, situated in the same latitude, are blocked nearly half the year. The high latitude of the islands is an advantage so far as the production of food-stuffs is concerned. The summer days in the latitude of Liverpool are very nearly eighteen hours in length, and this fact together with the mild winters, adds very largely to the food-producing power of the islands. The highlands afford considerable grazing. Great care is taken in improving the stock, both of cattle and sheep. In the north the cattle are bred mainly as meat producers; in the south for dairy products. Durham, Alderney, and Jersey stock are exported to both Americas for breeding purposes. The sheep of the highlands produce the heavy, coarse wool of which the well known "cheviot" and "frieze" textiles are made. Elsewhere they are bred for mutton, of which the "South Down" variety is an example. The lowland regions yield grain abundantly where cultivated. The average yield per acre is about double that of the United States, and is surpassed by that of Denmark only. Both Ireland and England are famous for fine dairy products. These are becoming the chief resource of the former country, which is practically without the coal necessary for extensive manufacture. The fishing-grounds form an important food resource. The cultivated lands do not supply the food needed for consumption. The grain-crop lasts scarcely three months; the meat-crop but little longer. Bread-stuffs from the United States and India, and meats from the United States, Australia, and New Zealand make up the shortage. The annual import of food-stuffs amounts to more than fifty dollars per capita.