When it is considered that in Scotland we have no such treasuries of the facts on which an archæological system must be built, as the Archæologia, the Vetusta Monumenta, the Nenia Britannica, the Ancient Wiltshire, and a host of other works supply to the English antiquary, I have a right to expect that some forbearance be shewn in contrasting this first attempt at a comprehensive treatment of the subject, with the works which other countries possess. I do not desire to offer it to the reader with an apology, or to seek to deprecate criticism by setting forth in array a host of difficulties surmounted or succumbed to. It has been the work of such leisure time as could be snatched from less congenial but engrossing pursuits, and will probably be found to contain some recurrence to the same ideas, to which a writer is liable when only able to take up his theme at intervals, and to pursue it amid repeated interruptions. Nevertheless, I have aimed at treating the subject as one which I esteem a worthy one ought to be treated, and if unsuccessful, it is not for want of the zeal which earnest enthusiasm commands. Some new ground I believe has been broken in the search after truth, and as a pioneer I am fully prepared to see my footsteps erased by those who follow me. It will be found, however, that truth is the goal which has been aimed at; and if it be but as a glimmering that light appears, it is well, so that its streaks are in the east, and the clouds which begin to break make way before the dawn. It only remains for me to acknowledge some of the many favours received in the progress of the Work; though it is impossible to mention all to whose liberality I have been indebted during the extensive correspondence into which I was led while collecting needful materials for substantiating the positions assumed in the following argument. The want of such resources as in other countries supply to the Archæologist the means of constructing a system based on trustworthy evidence, has compelled me to draw largely on the courtesy of private collectors; and with very few exceptions, the cordial response returned to my applications has rendered the otherwise irksome task a source of pleasure, and even in some cases the beginning of valued friendships.