champagne; and opinion became so “heady” that even the “Encyclopædia Britannica” in its eighth edition received the High Level Bridge as an inspired work, and gave to its engineering as much space as the thrifty Romans would have given to all their Spanish bridges and aqueducts. At last, and all of a sudden, a reaction came; enthusiasm not only caught a chill, it passed in a hurry from its tropical summer into a bad winter of discontent. Scientists went so far as to declare that the High Level Bridge was a youthful indiscretion, advertised publicly in a material which might endure for centuries; and this change of opinion had a great effect on the “Encyclopædia Britannica,” whose ninth edition gave only eighteen lines to its former favourite. Even the bowstring arch was praised no longer, “being essentially more expensive and heavier than a true girder.” [Illustration: THE TOWER BRIDGE, LONDON] Such are the comedies invented by our new playwright, the genius of civil engineers. Still, the High Level Bridge at Newcastle looks well on a misty day; by moonlight it is more impressive than a Whistler nocturne; and in Brangwyn’s art it represents our industrial age with a vigour that is manly and impressive. For the rest, from the pictures in this book you will be able to choose for yourself many a convention in the craft of bridge-building. Study, for example, the arches and their shapes, noting those which have a character of their own. These mark a new departure, and are famous. Thus the bridge at Avignon is admired by technicians because its architect, the great Saint Bénézet, gave to the arches what Professor Fleeming Jenkin has described as “an elliptical outline with the radius of curvature smaller at the crown than at the haunch, a form which accords more truly with the linear equilibrated arch than the modern flat ellipse with the largest radius at the crown.” Good Bénézet! Seven hundred and thirty years have gone by since he turned from the Roman tradition of semicircular arches, and designed an excellent arch of his own, a beautiful thing, with a look of triumph in its quiet dignity. Many writers think that L’arc de Saint Bénézet is original also in construction, its vault being composed of four separate bands put side by side in stones of about equal bulk. Sometimes this method of building is condemned as weak, though four of Bénézet’s arches have outlived seven centuries of war; and what engineer would feel disgraced if he were baffled by the terrific floods to which the Rhône is subject?