2-888-286 - The Print Collector/Heritage Images

The Victoria Tower - Elevation of the Hoisting-Screw, 1850. 'Progress of the New Houses of Parliament...M M being the guide-posts, which are 12 inches in diameter; and Q is the end of one of the main trusses. L is the screw itself, 3½ inches diameter; N N the screw-nut and carriage. The screw is acted upon by means of a winch; and, when the advanced state of the masonry renders it necessary to hoist the platform, the nuts and carriages are removed higher up the guide-posts; then the screws are worked up, carrying with them the platform, steam-engine, travellers, and everything upon them; the nut-head is then moved up to the required height, to aid in supporting the main and cross trusses, and remains there till the progress of the works renders a fresh lift necessary'. From "Illustrated London News", 1850.