_Third Period_, 1400-1550.--With the coming of peace and a period of commercial and industrial prosperity, the nobles of Scotland were able to observe the progress of castellation around them in England and France, and began to adopt the styles which they found in those countries. A type of castle appeared based like that of Bodium upon a French ideal,--the building of a high embattled wall strengthened with towers around a quadrangular space. This plan, derived from the Concentric ideal, was adopted for the largest castles, such as Stirling, which is the most perfect example of a courtyard plan, and Tantallon. In the smaller castles the Hall is placed in the centre with the kitchen, pantry, and buttery adjoining it, and the lord's solar and private apartments at the daïs end. The wine-vaults and cellars are built beneath, while the bedrooms occur above. In contrast to the English buildings of the period, the question of defence was the dominating idea in spite of the altered conditions of better living and increased luxury. Many plain and simple Keeps were also built during this period. _Fourth Period, after_ 1550.--The development of artillery led to alterations being made in castellation, while the progress of the Reformation gradually introduced the fortified mansion and Manor-House. Many small Keeps, or Peel Towers, were built, however, chiefly on the Border. Ornamentation up to this period had been conspicuously absent, but now it assumed a very high importance. Corbelling became almost a mania,--floors, windows, parapets, chimneys, and other details projecting to an excessive distance in order to enhance the effect. The bartizans were covered with high conical roofs, and turrets similarly ornamented became a prominent style. The accommodation in the upper floors was greatly increased when compared with the basement, through the excess of corbelling. Gables were furnished with crow-steps, while machicolation became at times almost fantastic. Gargoyles shaped like cannon in stone are a marked feature of the period. _Bothwell Castle, Lanarkshire (1st Period)_