A.W. HENDRY University of Edinburgh

Perception of the structural behaviour of masonry arches dates back to the early 18th century and methods for the design of arch bridges were developed through the 19th century in the course of which many thousands of these structures were built for roads and railways. Since the beginning of the present century the use of masonry for bridges has been superseded by steel and concrete. As a result, knowledge of the techniques used for the design of masonry arches is no longer familiar to engineers. Arches were proportioned by experience or by empirical formulae and the design verified usually by consideration of the line of thrust. The methods used and the approach to safety are summarised. It is concluded that the procedures adopted were appropriate to the indeterminate nature of the structure and some comments relevant to current practice are put forward.