From what has been previously stated, it may be gathered that the base-pieces had to be fixed truly upright in one direction, but slightly inclined in the other; and to effect this a plumb-rule was made, on which the deviation from the perpendicular line was marked; and this, when applied to those faces of the base-pieces which were to incline, served to show when the proper inclination was arrived at, whilst an ordinary plumb-rule applied to the other upright faces tested their vertical position. The first column was raised on the ground on the 26th of September, but little more than two months after the tender had been accepted. In the meantime, many of the different castings had already arrived on the ground, and a considerable advance had been made in the carpenter's work for the gutters and other parts. The semi-circular ribs for the transept roof were also being put together, and stacked in such a manner as not to stand in the way of the other works. [Illustration: VIEW OF CRANE AND PROVING-PRESS.] We may mention here that every casting, as it came on to the ground, was weighed and registered, and every girder proved, as already described; in doing which considerable assistance was derived from one of Mr. Henderson's patent Derrick cranes, which was erected near the proving-apparatus. By its means a girder was raised from the waggon in which it arrived, placed on the weighing-machine, weighed, removed to the proving-press, tested, raised again, and deposited on the ground in a stack, in less than four minutes. Henderson's Derrick Crane. [Illustration: (FIG. 1.) HENDERSON'S DERRICK CRANE.] [Illustration: (FIG. 2.) PART OF HENDERSON'S DERRICK CRANE.] [Illustration: (FIG. 3.) PART OF HENDERSON'S DERRICK CRANE.]