For many years the galleries thus eulogized by the Duke were in course of construction, and are formed, as already stated, by deep excavations in the solid rock. Passing round the north face in two tiers,[37] mounting about forty pieces of heavy ordnance, they command the approach to the fortress from the neutral ground, and render it almost impregnable on that side. Large magazines and spacious halls—in like manner hewn out of the rock—are attached to them. The work, as a whole, executed principally by the jumper and blasting, is curious and even marvellous, bearing also unequivocal evidence of ingenuity and of immense labour. Than these subterranean passages and chambers, no better testimony need scarcely be desired of the successful superintendence of sergeant-major Ince and of the skill and exertions of the company. ----- Footnote 37: Called Lower, or Union Galleries; and Upper, or Windsor Galleries. ----- Notwithstanding the formidable character of these defences, doubts seem to exist as to their real efficiency in a siege. These doubts have arisen from the idea that the report of the explosion would not only be deafening, but that the smoke would return into the galleries and suffocate the men.[38] No experiments have ever been made with the view of ascertaining these particulars: speculation is therefore properly admissible. Once, indeed, in 1804, they were fired in salvo to dispel, if possible, the then raging fever;[39] and at distant intervals since, _some_ of the guns have been discharged; but no complaint was ever made—at least became public—of the inutility of these galleries from the causes stated. To expect a loud report is certainly natural, but much less so the recoil of the smoke, as a strong current of air is always passing in the galleries, and rushing with some force through the embrasures. No matter how sultry the day, how still the air, or how fiercely the sun may beam upon the Rock, in these galleries a strong breeze is constantly felt; and the fresher the wind from the outside, whether from the north-east, and blowing directly into the embrasures, or sweeping round the Rock, the stronger is the current within the galleries to force back or disperse the smoke. But little, therefore, of the vapour can find its way back, and that little must be _much less_ annoying to the gunners than in an open field when, firing smartly in the teeth of the wind, the whole volume turns back and beclouds them as long as the cannonade continues. However, should the alleged defect be found on trial to exist, there is no reason to fear but that the military engineer will readily adopt some effectual contrivance for removing the annoyance, and for obtaining all that power and efficiency which the galleries were designed to possess and should be capable of commanding. ----- Footnote 38: