File:Forth Bridge - Superstructure, North Side.jpg

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Forth Bridge - Superstructure, North Side   (Wikidata search (Cirrus search) Wikidata query (SPARQL)  Create new Wikidata item based on this file)
Photographer
Title
Forth Bridge - Superstructure, North Side
Description
Photograph of the Fife superstructure (lifting girders and platforms). Owing to the fact that the Fife cantilever occurs on the foreshore and is overlooked by rising ground to the north, it afforded an opportunity of obtaining certain views not practicable in the case of the other two. Not only did its situation admit of perspective effect being duly emphasised, but also that of the rectangular form of the structure, only apparent when each vertical column is separately defined. The cages before referred to are all seen here in position prior to the first lift. Up to this level the superstructure was erected by means of ordinary cranes and staging. In the vertical columns and at a height of about 30 feet above the surface of the pier, a plate was omitted on either side of the same. In the gap thus formed were built two box girders, having a dimension of about 5 feet by 2 feet. Superimposed upon these girders were what were subsequently known as the lifting platrofms - comprised of material destined to be ultimately worked into the permanent structure - and through which the upper ends of the vertical tubes and struts projected. The total weight of these four girders and their accessories amounted to about 400 tons, the whole being supported by and lifted from the vertical columns in the following manner:- Inside each of these columns were constructed two frames, the upper side of the one being connected to the lower of the other by means of hydraulic jacks contrived in such a way as to oscillate in a plane at right angles to the centre line of the bridge. Through the rigs of the columns holes were drilled at equal distances apart, and into these holes steel pins were inserted supporting either frame. Everything being ready for a lift the jacks were set in motion, the thrust being taken by the lower frames and duly transmitted to the pins. At the end of the stroke pins were inserted below the under side of upper frame and the jacks eased, whereupon the whole weight of the platform came upon the upper frame, the lower one, simultaneously drawn up by the closing of the jacks and secured by pins, being at once in readiness for another lift. The rate of progress was to a large extent governed by the weather, but under favourable circumstances it was extremely rapid, as many as three lifts having been effected in eight days, and the necessary riveting accomplished in the cages attached. The tension girder connecting the vertical columns from east to west is noticeable in the foreground of the picture, as is also a part of the diagonal bracings, which is designed to afford the principal support fo the internal viaduct. The gallows so conspicuous above the vertical columns on the lifting-platforms answer the purpose of cranes and were employed in lifting and holding the plates in position until temporarily bolted. The means of access to the upper part of the structure, independently of lifts, is shown in the staircase running up the diagonal bracing and subsequently continued in a similar fashion to the full height of the superstructure. Transcription from: Philip Phillips, 'The Forth Railway Bridge', Edinburgh, 1890.
Date between 1886 and 1887
date QS:P571,+1886-00-00T00:00:00Z/8,P1319,+1886-00-00T00:00:00Z/9,P1326,+1887-00-00T00:00:00Z/9
Medium photograph
Dimensions height: 43 cm (16.9 in); width: 58 cm (22.8 in)
dimensions QS:P2048,43U174728
dimensions QS:P2049,58U174728
institution QS:P195,Q1670994
Accession number
74570312
Source
This image is available from the National Library of Scotland under the sequence number or Shelfmark ID RB.l.229. You can see this image in its original context, along with the rest of the Library's digital collections, in the NLS Digital Gallery
Permission
(Reusing this file)
Public domain

This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 70 years or fewer.


This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1929.

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current13:50, 13 June 2014Thumbnail for version as of 13:50, 13 June 20142,500 × 1,861 (3.88 MB)wikimediacommons>ACrockfordGWToolset: Creating mediafile for ACrockford. Upload NLS Forth Bridge photos

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