With the completion of this edition the progress of improvement was for a time suspended; but in 1814 the copyright of the work was purchased by Archibald Constable, who, with the enterprise that always distinguished him, at once projected a supplement, which extended to six volumes. It was placed under the skilful management of Professor Macney Napier, and the publication lasted from 1815 to 1824. Many very distinguished authors were engaged as contributors, among whom we may specially mention Arago, Biot, and Dugald Stewart; and all the resources of the proprietors were devoted to this favourite undertaking. In 1829 the whole of the copyrights (including that of Professor Robison’s supplementary articles) passed into the hands of Messrs. A. and C. Black, assisted by their friends; and we are now able to resume our narrative at the point we left it. The property was at first a joint stock concern, resembling the original proprietorship, and was, we believe, owned in equal shares by Mr. Abraham Thomson, as the binder; Mr. Thomas Allan, as the printer; and Messrs. A. and C. Black, as publishers. Mr. Thomson died shortly afterwards, and the Messrs. Black became the possessors of his interest in the work. Some years afterwards, the share held by Mr. Allan, who was a banker in Edinburgh, and also printer and proprietor of the _Caledonian Mercury_, also fell into the hands of the Messrs. Black. At this time the new edition was in midway progress, and the enormous expense necessary to complete the work rendered the venture single-handed something more than hazardous. But the ability, tact, immense energy, and unceasing labour of Mr. Adam Black, then in the prime of life, proved equal to the task he had undertaken, and in this case it may truly be said that for years he went on literally scattering bread upon the waters, and most deservedly did he obtain his reward. Previously, we believe, to the completion of this edition, Mr. Charles Black, who had long been in delicate health, died.