In Ecclesiastical Architecture the case is different. The various styles and periods of Gothic architecture, both in this country and abroad, have for long been carefully investigated and defined. It thus only remains to apply to our Scottish edifices the system already adopted in the rest of Europe. An attempt is made in this work to do so, and attention is drawn to the various points in which Scottish Church Architecture agrees with and differs from that of other countries. It has been suggested that our Ecclesiastical Architecture might be arranged in connection with the various orders of ecclesiastics by whom it was employed, and the specialities of the architecture of the various orders pointed out. This matter has not escaped attention; but it has been found impossible to form a system of nomenclature on that foundation. The more this subject is investigated, the stronger is the conviction that there is, in this country at least, practically no difference in the style of architecture of the different orders of Churchmen from the twelfth to the sixteenth century. The cathedrals and parish and other churches were all built on general and well understood principles. The monasteries also were all constructed on the same general plan. Whether the occupants were Canons Regular or Monks of the Cistercian, Tyronensian, Premonstratensian or other order, or even Franciscans or Dominicans, their convents were all designed on one general system. The plan consisted of an open court or cloister, surrounded by a covered walk, having on one side (generally the north side) the nave of the church; while on the east side, in connection with the transept, lay the sacristy, chapter house, and frequently the fratery or day-room of the monks, on the upper floor of which range extended the dormitory, library, &c. The south side of the cloister was occupied by the refectory and kitchen; and the west side contained cellars and stores, and apartments for the lay brothers and guests. These dispositions were sometimes extended and modified, but were invariably adhered to on the whole. None of our Scottish monasteries are sufficiently well preserved to exhibit these arrangements in their entirety; but the various portions of the different convents which survive always correspond with the parts which would be expected in the positions they occupy. As regards the style of the architecture and ornamentation, the only difference observable is that which is common to all the structures of the respective periods. While it is intended to include in this work all the examples of ancient church architecture discoverable in Scotland, such subjects as ancient sites, demolished structures, and mere foundations do not fall within its scope, and are only referred to incidentally. These matters belong to the province of archæology, not to that of architecture.