Linlathen East Iron Bridge

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Dighty Water, Linlathen, near Dundee, Angus, Scotland

An early iron bridge. One source suggests that it was built 'some time between 1795 and 1810, probably around 1804', making it the oldest in Scotland. Linlathen East Bridge was built as one of two approaches to the now-demolished Linlathen House. Clear span 10.7m. Sandstone buttresses..

See Canmore entry.

In recent years the bridge was dismantled by Eura Conservation Ltd, removed to their workshops for restoration, and has now been reinstated. Reinforcing framework has been introduced very discretely below the deck, and additional handrailing introduced inboard of the wrought iron railings, with posts attached to the new underframe. Some of the original ironwork was replaced with new items.. Steelwork introduced during restoration is distinguished by its grey finish.

Construction Date

The construction date is unknown. One source stated that the owner of Linlathen House, David Erskine, left for Naples with his wife and cousin, and he died there in 1791. '.... Linlathen House remained unoccupied until the marriage, of Mrs Erskine’s eldest living son, James, with his cousin, Kathrine Stirling of Kippenross, when the young couple took up their permanent abode there.'. Tenuous, indeed, but it might suggest that improvements including the introduction of the bridge were not carried out before 1811. James Erskine died in Broadstairs in 1816

'Linlathen House was built for David Graham in 1705 and extended for Thomas Erskine by William Sterling [Stirling] in circa 1830. ... The south drive, lodge and gates do not appear on the 1827 plan of the estate but are shown on the 1857-58 OS map and with the cast-iron bridge over the Dichty were clearly built to form a new and more impressive entrance to the extended house.'.

However, another source sates that between 1820 and 1826 architects William Stirling I & II were engaged in the reconstruction work and construction of a new wing at Linlathen House.

Construction

The wrought and cast iron members are particularly slender.

Iron arch bridges with 'diminishing spandrel rings' were popular for a period in the early 19thC, but these were usually constructed from cast iron. Examples predominantly made from wrought iron are very rare. In fact the only other known example in Britain is the small Cathedral Close Footbridge, Exeter, built in 1814

The bridge has a superficial resemblance to a number of other early iron bridges, with a series of rings of diminishing diameter in the spandrels. In this case the designer provided a whimsical touch by reducing the circles to extremely small diameters (photos 4 & 10). It was usual to make the rings of cast iron, or more rarely, wrought iron, but in this case the large rings are wrought iron, while for practical(!) reasons the smaller rings are cast iron, moulded as groups. In photo 5, the four rings nearest the camera are forged from wrought iron, while the others are cast as a group (it will be seen that they are slightly thicker).

Another unusual feature is the combination of cast and wrought iron arch beams at deck level with arched wrought iron rims below. See photo 5, which also shows how the lower ribs are doubled for part of their length by clamping two bars together. The cast iron arch beams are thin-walled (photos 6 & 7), but they presumably provide some vertical and lateral stiffening, while their lower flanges also support the 'palms' of the cross members (see below), the upper flanges serve to attach the handrailing, and the castings make for a neater appearance. In fact the cast iron and wrought iron arches are not continuous. Each wrought iron member is made in two pieces, while the cast iron members are each made in four pieces, and all are joined at the crown of the arch by an iron casting, which can be regarded as serving a similar role to that of a keystone on a masonry bridge. This casting can be seen in photo 4 (outer face) and photo 8 (inner face).

A further notable feature is that the cross members which support the deck ribs are trussed (photo 9). The main part of each cross member forged from flat wrought iron bar, offset and twisted at the ends to form 'palms' (see photo 10). The trussing comprises curved wrought square iron rods with kingposts and intermediate struts. It is not clear how the ends of the rods are connected to the flat bars, but they may well have been forge-welded.

Additional wrought iron arch ribs are located below the deck. Photo 11 shows the arrangement where they meet the cross members. Much blacksmith's manipulation required, as for the palms of the cross members.

Photo 13 shows a pair of stamped concentric circles on the wrought iron bar. A similar mark can be see in photo 14, LHS. An early example of a rolling mill brand mark?

Photo 12 shows a bolted joint between sections of the cast iron arch beam, using a fishplate. This is a rough piece of cast iron, which itself appears to have broken. The beam has also been bolted to the wrought iron rib at this position.

See Also

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