Scattered throughout the British Isles are approximately 200 iron aqueducts and bridges that were built between the 1770's and the 1850's. Some are magnificent and much celebrated but many are quite modest and utilitarian. Their significance to engineering history is fourfold. They represent a complete departure from the way bridges had always previously been built. They were one of the first structural uses to be made of an improved iron that was developed in Britain during the 18th century. They occur for the most part only in the British Isles and virtually all such bridges were built within that 75 year time period. They were an integral part of the new transportation system being created by that pioneering generation of civil engineers. {6, 3}
They share other characteristics that are less tangible. They are endangered: by groundless health and safety fears, liability concerns, and public ignorance of their significance. They were an astonishing innovation in their day. Our generation is so used to the airy grace of suspension bridges and the satisfying geometry of truss bridges that it is hard for us to realize how radical those iron bridges seemed to a generation whose serious bridges since time immemorial had always been built of solid and substantial stone. To the modern generation, they seem quaint or venerable depending on their scale, but invariably something of their original audacity is expressed with Georgian grace and flair as 230 years later they continue to serve their original purpose. They are very much part of our British heritage. Even the most modest of them deserves to be celebrated and protected.
They are almost invisible in plain sight as part of the fabric of their community. Yet to made aware of their historical significance is to them in a new light and to almost invariably become captivated by them. That partiality can be translated into public advocacy for their retention and repair. {11}
The purpose of making an inventory and of photographing them beautifully from every relevant angle and of pinpointing their location and of recording their history and the details of their construction and of finally making this archive easily accessible to the profession and to the public is to accomplish the first rule of historic preservation: to create a personal connection between the object to be saved and the entity or individuals who can make that happen.