This Survey was probably grounded partly on traditions of taxation, as early as the Norwegian Conquest, and partly upon the _Matricula Regis_, King Sverrer’s Register of the Odals confiscated under penal terms of redemption (1196)—and from its results was compiled the first LIBER CENSUS, or SKATT BOOK of Orkney and Zetland, the authentic Statement of the extent of each Odal Tun then in occupation, and of its STENT or proportion of Butter Skatt. As population increased, each _Tun_ or subdivision thereof paid for its enlarged area of cultivation a Malt Skatt also, marking at once the advance from pasture and the increase of culture; and the old _Liber Census_ was from time to time replaced as out of date, by a new and more complete record of such changes. The only specimen extant is a copy of the SKATT OF ZETLAND, compiled by one of the Sinclair Earls, without a date, but so ancient that the scribe of the fifteenth century apologises for the illegible writing and uncouth terms, as unintelligible even to himself. This Skatt Book distinguishes each Thing; describes the extent of each Tun in Marks of so many pennies per mark; and under distinct heads charges against each possession its Odal-Skatt and Leangr, or Tenant’s Land-male of wadmæl, oil, or fish—or sometimes both Odal and Tenant burdens; probably because such lands, though formerly Odal, had fallen by confiscation to the King or Earl, and been set to a tacksman, subject to both the old and new exactions. But though it thus records a few _land-males_ (showing the small extent of land in Zetland under tacksmen), the Skatt Book seems to have been a fair and distinct statement of National Taxation, unblemished by the studied confusion of tax and rent, of Odal and Feudal terms, which rendered its successor, the Rental, so oppressive to the Odaller. Like the Doomsday Book of another Northman race, the Skatt Book was the simple Record of the revenue and rule of taxation—its successor, the Scottish Rental, claimed to be also the substitute for a written title, the limit of every claim, the standard of every burden, the authority for every exaction; but compiled in secret, and jealously closed against public inspection, it rather favoured the claims of the ruler than secured the rights of the subject. The first duty imposed by James III. upon his new vassals, the Earl and Bishop of Orkney, was the compilation of such a rental, including not only the land-males or rents of his own newly acquired Earldom, and of the Church lands, but also the whole Skatts and other Odal taxes of the Skatt Book, exigible from the lands of free Odallers. The “AULD PARCHMENT RENTAL,” Earl William’s last legacy of spite against the Bishop and the Odallers, has unfortunately been lost, but it is evident from other authorities that he revenged himself on the Churchman by pitiless exposure of his fraud and rapacity, and on the Laymen, by suggesting the close similarity and easy identity of Odal and Tenant rights and burdens.