The question of the strength of the galleries was one of even greater importance than the other, as, in case of any failure in that part of the building, human life must almost inevitably have been sacrificed to a great extent. It was therefore deemed necessary to ascertain, as far as was practicable, by experiment, that their strength was abundantly sufficient; and in Mr. Wyatt's paper, as printed, the following description of the experiments instituted for this purpose will be found. Testing the Galleries. In the interval between the reading of this paper and its going to press a series of experiments have been tried to ascertain the action of these galleries under the strain of a moving load. A complete bay, twenty-four feet square, was constructed, raised slightly from the ground, consisting of the four cast-iron girders, with the connecting-pieces at the angles, and on this the timbers and boards of the flooring. Rows of planks the full width of the platform led up to it and down from it, so that a body of men as wide as the gallery might be able to march up and down in close rank. "The area of the platform was first covered over with labourers packed as closely together as possible; but no action of walking, running, or jumping that 300 men could perform did any injury whatever to it, and the greatest deflection of the girders did not exceed a quarter of an inch. Soldiers of the corps of Royal Sappers and Miners were then substituted for the contractors' men; and although the perfect regularity of their step in marking time sharply appeared a remarkably severe test, a minute examination of the construction after the completion of the experiments showed that no damage whatever had been done by their evolutions. "But as the Commissioners were deeply impressed with the necessity of thoroughly convincing the public, who should visit the Exhibition, that they might feel perfectly secure in every part of the building, it was deemed desirable to apply a still further test to the actual galleries as they stand; as it might perhaps be said that the single bay which had been experimented upon was not similarly circumstanced to those forming parts of the building. [Illustration: Testing the Gallery Floor.] [Illustration: View of the Boiler House.]