The works of the Romans, and, following them, those of almost all Western Christian nations, were designed to unite external and internal effect; but in many cases external was evidently most sought after, and, in the North of Europe, many expedients--such, for example, as towers, high-pitched roofs, and steeples--were introduced into architecture with the express intention of increasing external effect. On the other hand, the Eastern styles, both Mohammedan and Christian, especially when practised in sunny climates, show in many cases a comparative disregard of external effect, and that their architects lavished most of their resources on the interiors of their buildings. Passing allusions have been made to the influence of climate on architecture; and the student whose attention has been once called to this subject will find many interesting traces of this influence in the designs of buildings erected in various countries. Where the power of the sun is great, flat terraced roofs, which help to keep buildings cool, and thick walls are desirable. Sufficient light is admitted by small windows far apart. Overhanging eaves, or horizontal cornices, are in such a climate the most effective mode of obtaining architectural effect, and accordingly in the styles of all Southern peoples these peculiarities appear. The architecture of Egypt, for example, exhibited them markedly. Where the sun is still powerful, but not so extreme, the terraced roof is generally replaced by a sloping roof, steep enough to throw off water, and larger openings are made for light and air; but the horizontal cornice still remains the most appropriate means of gaining effects of light and shade. This description will apply to the architecture of Italy and Greece. When, however, we pass to Northern countries, where snow has to be encountered, where light is precious, and where the sun is low in the heavens for the greater part of the day, a complete change takes place. Roofs become much steeper, so as to throw off snow. The horizontal cornice is to a large extent disused, but the buttress, the turret, and other vertical features, from which a level sun will cast shadows, begin to appear; and windows are made numerous and spacious. This description applies to Gothic architecture generally--in other words, to the styles which rose in Northern Europe. [Illustration: FIG. 6.--TIMBER ARCHITECTURE. CHURCH AT BORGUND.]