Religious Emblems or Symbols on Historic Bridges, such as the Phallus on the Pont du Gard, [174]; the Janus heads on the Pons Fabricius, [196]; the idol or image on the Chinese bridge at Shih-Chuan, [247]; and the cross and crucifix on Gothic bridges of the Middle Ages, [96], [230], [246]. The symbolic lion and tortoise on the Chinese bridge of Pulisangan were borrowed from the singa and Kûrma of Hindu mythology, [311 footnote]. I should like the cross to be raised again on all bridges in unfortified towns, as a protest against a Teutonic misuse of flying warfare.

Rennie, John, b. 1761—d. 1821, his poor bridge over the Thames at Southwark was financed by a Company, not by the City, as if London were a trivial village with some new industries that needed encouragement, [326-7].

Rennie, Sir John, son of John Rennie and brother of George Rennie, was the acting engineer during the building of New London Bridge, according to Professor Fleeming Jenkin.

Rhône, the River, his two famous old bridges, the Pont St. Bénézet and the Pont St. Esprit, both constructed by the Frères Pontifes, or Pontist Brothers. See Brangwyn’s pictures and the text.

Ribbed Arches, like those in the Monnow Bridge at Monmouth, [281], and the Pont de Vernay at Airvault, Deux-Sèvres, plate facing page [96]. The introduction of ribbed vaulting into English churches and bridges, [93-100]. Professor Moseley’s remarks on groined or ribbed arches may be quoted here from Hann and Hosking’s profuse volumes. “The groin ... is nothing more than an arch whose voussoirs vary as well in breadth as in depth. The centres of gravity of the different elementary voussoirs of this mass lie all in its plane of symmetry. Its line of resistance is therefore in that plane.... Four groins commonly spring from one abutment; each opposite pair being addossed, and each adjacent pair uniting their margins. Thus they lend one another mutual support, partake in the properties of a dome, and form a continued covering. The groined arch is of all arches the most stable; and could materials be found of sufficient strength to form its abutments and the parts about its springing, I am inclined to think that it might be built safely of any required degree of flatness, and that spaces of enormous dimensions might readily be covered by it.” Yet “modern builders, whilst they have erected the common arch on a scale of magnitude nearly approaching perhaps the limits to which it can be safely carried, have been remarkably timid in the use of the groin.” Progress may be compared to a dilatory army that ever fails to march forward with all its needed units.

Ring of an Arch, the compressed arc of voussoirs, [264]; the lower surface of a ring is called the soffit of an arch. In some bridges the voussoirs form a double or a triple ring, [305], and [footnote]. Two very fine bridges of this sort, in my collection of photographs, are the Pont de Vernay at Airvault, 12th century, and the Pont Saint-Généroux over the Thouët, also in Deux-Sèvres, 13th and 14th centuries. Another monument to be studied is the reputed Roman bridge at Viviers over the Rhône, built mainly with small materials. Whether Roman or Romanesque, the structure of the arches has great interest, and a large photograph is sold by Neurdein, 52 Avenue de Breteuil, Paris.