a circumstance which strikingly shews, that a small, and, apparently, trifling alteration in the style of workmanship may sometimes increase to a considerable extent, the expense of a great work. Each radiating stone of the _eighty-fourth_ course, which forms the floor that goes quite through the wall, required _one hundred and sixty-one hours_ for its completion; and the other radiating floor-stones, which did not pass quite through the wall to the outside, occupied one man about _one hundred and twenty hours_. Each centre stone of the floors into which the others were dovetailed, required about _three hundred and twenty hours_ of one man’s time. The time of a labourer occupied in cutting a hole for the dovetailed Lewis bats, by which the stones were raised, was about _three hours_. The tools necessary fully to equip a granite mason are as follows:--One dressing hammer about 16 or 18 lb. weight; 6 dressing picks, from 12 to 20 lb. weight; one small hand-mall, or mash-hammer, about 4 lb. weight; 3 stone axes about 7 lb.; 16 or 18 cast-steel punches and chisels, with one or two chippers or pinchers of 2¹⁄₂ lb. weight. One large blocking-hammer of 30 or 32 lb., may very well serve for eight men. The value of a granite mason’s _kit_ may be estimated, when in good working order, at about L.7. A very great revolution has taken place during a few years in the method of working granite. The most important change is the substitution of the hand-mall and chisel in the operation of putting the _drafts_ or bands on the stones, in place of _arris-picks_, which made the workmanship clumsy, tedious and imperfect, by slowly grinding down the stone at a great expense of labour to the hewer, who was forced to remain bent forward in an irksome posture, without the relief which is obtained by occasionally shifting his position, a change, which, every one who has been long employed in any laborious occupation, knows well how to value. The introduction of the _chipper_ may also be regarded as one of the most important modern improvements in the art of working granite; and had it not been for those changes, the actual expense of dressing the blocks for the Skerryvore Tower, as ascertained from the journals of the works, would have been exceeded by a sum of between L.4000 and L.5000; and it may even be questioned whether it would have been at all practicable with such tools to cut the dovetailed spaces of the floors out of the solid stone. ~Excavation of Foundation for the Lighthouse Tower on the Skerryvore Rock.~