These, and other matters of minor importance alluded to in this report, having been adjusted by the Light-house Board, the writer took the necessary measures for entering into contracts and agreements for the supply of stones from these quarries. The difficulties which subsequently attended the procuring of a regular supply of stones for the work have already been alluded to; and to this subject we shall again have occasion to recur, as it was ultimately found necessary to restrict the use of granite to the outward casing of the first thirty feet or solid part of the building. [Sidenote: Mortar of the ancients.] The best composition for building-mortar appears to have been a problem from the earliest history of the arts. Vitruvius, who lived about 130 years before the Christian æra, seems to have been practically, as well as scientifically, acquainted with the whole subject of architecture. But, although he, and other eminent authors who followed him, have minutely treated of the composition of mortar, stating, no doubt, all that was known of the practice of the ancients; yet, it has always been a favourite maxim to maintain, that the secret of compounding mortar has at some period of its history been irrecoverably lost. It is certainly true, that many of the works of ancient times exhibit wonderful specimens of the excellency of their building materials. It may, however, be drawn no less conclusively from the writings of intelligent travellers, that many of their finest edifices have been subject to premature decay, which affords a proof that at least no systematic rule was universally observed in the preparation of their calcareous cements; but that, like the artists of the present day, the quality of their materials depended much upon those adventitious circumstances which too often regulate the views of their successors, by an over-anxious desire for economy, without keeping duly in view the permanency of their works. [Sidenote: Attention of the moderns to this subject.]