"For this purpose a very ingenious apparatus was devised by the late Mr. Field, President of the Institution of Civil Engineers, for testing the stability of the galleries _in situ_, and on being applied over the greater part of the building not a single bolt or girder gave way under its action. This apparatus consisted of eight square wooden frames divided into thirty-six compartments, each just capable of containing and allowing to rotate a 68-pounder shot. The surfaces of the balls placed in each of these compartments came in contact with the gallery floor, the frames themselves being attached to one another and running along the floor by means of castors fixed at the angles; the whole apparatus being drawn along by a number of men. Two hundred and eighty-eight 68-pound shot confined in a limited area were thus set rolling over more than half the extent of the galleries; when, not the slightest mishap having occurred, the experiment was considered decisive, and a persistence in it deemed unnecessary." The pressure obtained in this experiment amounted to about a hundred pounds per square foot, and it had been ascertained that the greatest pressure caused by packing men together as closely as possible was equal to about ninety-five pounds per square foot; so that the testing force applied was considered amply sufficient, as a considerable portion of the surface of the gallery will be occupied by light articles exhibited in the cases and stalls which are placed along the centre of the gallery, where a great weight would have most effect. This ingenious method of proving the strength of the galleries _in situ_, without endangering those engaged in the experiment, is admirable; and the result of the proof will no doubt allay all fear in the mind of the public as to the safety of this portion of the building. General Advantages of the Building. It is always much easier to point out the defects of any work than its excellences; whilst we may, therefore, safely leave the former, as regards our present subject, to be discovered and enlarged upon by those who may be perhaps more competent than ourselves, we will attempt to point out what we conceive to be some of the advantages obtained in the present building.