78

CONSTRUCTION OF THE BUILDING.

The increasingintensity of thework evidencedby-

The number ofhands employed.

Raising of the72 and 48 feettrusses;

Facilities for theabove.

The beginning ofDecember thetime of theclimaxofactivity.

Framing togetherof the transeptribs preparatoryto raising.

boarding, louvre frames, &c., for the external enclosures. The vertical sash-bars,cut at the Phoenix saw-mills, were delivered by Mr. Birch in large quantities.Sash-frames, also cut at the same mills, were supplied, and these were fitted toge-ther by the contractors’ carpenters, whose time and labour in forming morticesand tenons was much economised by the employment of the machine beforealluded to, patented by Messrs. Furness & Co.

As supplies of the smaller castings necessary to complete the various portionsof the structure poured hi, the work of erection and putting together proceededwith wonderful rapidity. The progressive increase in the number of handsemployed affords a tolerable indication of the increasing intensity of the work :—

1850. In the week ending Sept. 6,

, , Oct. 4,

, , Nov. 1,

, , Dec. 6,

1851. , , Jan. 3,

39 men were employed.

419

1,476

2,260

2,112

And from that time, until within a month of the opening of the Exhibition, theaverage number has rarely fallen below 2,000.

The task of raising to their places the 48 and 7 2 feet trusses was accomplishedwith great facility in the following manner :—A single mast was maintained in avertical position by ropes, similar to those described as steadying the shear-legsused for hoisting the girders. From the summit of this mast descended otherropes, with blocks and pulleys, for the purpose of gaining power in lifting. Whatis called a leading or guide-block, having been attached to the bottom of the mast,a rope passing through it was connected with a yoke drawn by a horse. Themast having been placed close along side the line in which the roof-trusses had tobe fixed, and one end of a rope secured to the truss, the draught of the horsecaused the truss to ascend to the necessary height, being steadied in its ascent byother ropes secured to its two ends.

When the truss thus hoisted was fixed in its resting place, the mast was movedalong a plank by means of crow-bars, being maintained in a perpendicular posi-tion by the alternate slackening and tightening of the cords extending from itshead to stakes driven into the ground. Having thus been moved 24 feet, it wasready for the operation of a second hoisting. Two of these great masts, fixed oneach ‘side of the transept, were used daily, and in one day as many as seven ofthe great 72-feet trusses have been raised to their proper position and secured,the apparatus for elevating them having travelled in a vertical position no lessthan 168 feet.

Towards the beginning of December the climax of activity was arrived at, andthe most trying operation in the whole construction of the building commenced,namely, the hoisting of the main ribs for the great transept roof. The easiestand at the same time the most secure method of proceeding, with respect to theconduct of this operation, had for some tune occupied the attention of the con-tractors. An ingenious suggestion, made to them by Mr. Wilbee, one of theirforemen, was at once adopted, and with certain modifications, it was promptlycarried out.

The floor for the lead flat was already completed, so that an admirable stage wasprepared upon which to make the necessary arrangements. The ends of the columninto which it was designed to drop the ends of the ribs, rose about four feet above