1. Those which are low and many-arched, as at Mérida and Salamanca.
2. Those which have two or three arches with shelving parapets and roads, as at Alcantarilla[70] and also near Villa del Rio;[71]
3. One or two with a single arch, as at Ronda;
4. Several in which Roman and Moorish masonry are combined, as at Córdova; and
5. There is one Roman bridge so lofty that its parapet is separated from the river-bed by a distance of more than fifty-nine metres. I refer to the famous Puente Trajan over “the melancholy Tagus” at Alcántara. This herculean masterpiece has six arches, his length is a hundred and eighty-eight metres, and the roadway is eight metres wide and quite level. A triumphal archway thirteen metres high stands in the middle, but I regard its Roman origin as doubtful, as the design is not quite in scale with the majesty of the bridge.
Who can say how many writers have tried to describe the Puente Trajan? No description can summon up before the mind an image of his marvellous power and nobility, for these qualities produce a feeling of awe and take from us the wish to write. That he came from an architect and was put together by common masons, huge stone after huge stone, is a fact very hard to believe, as only two things in this bridge mark the littleness of man: one is the archway, that fails to triumph with a Roman spirit, and the other is an arch of modern workmanship. Everything else recalls to my mind a good saying that fell from Marshal Ney when he noticed in the aqueduct of Segovia the startling difference between the craft of modern masons and the ancient Roman art in thorough construction. In the fifteenth century some vaults of the Segovian aqueduct were destroyed by wars, and Isabella the Catholic had them rebuilt in the most careful manner. Yet the work was not careful enough, for in less than three hundred years the reconstruction had to be renewed, while the Roman art remained youthful and immovable. In 1808 Marshal Ney was greatly impressed by these facts, and, pointing to the first arch of the modern portion, he said: “C’est ici que commence le travail des hommes.” Even the people of Segovia feel that their soaring aqueduct has in it something far beyond their reach, something grand enough to be called superhuman. Custom has deadened their admiration, of course, has enabled them even to build silly little houses amid the shadows thrown by their antique monument; but yet they doubt the human origin of such perfect masonry and give it to the Evil One, who comforts himself with a tremendous deed of architecture whenever he is greatly bored by the feeble gullibility of mankind.
THE ROMAN AQUEDUCT AT SEGOVIA IN SPAIN, WITH MODERN HOUSES CLUSTERED AROUND ITS BASE
Nothing is more difficult than to express in words this unhuman character of the best Roman bridges, which reveal eternal manhood and courage in the work done by the men of a day. For instance, here is the Alcántara over the rocky gorge of the Tagus. He was erected for Trajan by Caius Julius Lacer; and we know that Lacer was buried quite close to his bridge, and that his tomb remains on the left bank. These facts are trite and tame, but when we turn from them to the supreme bridge we pass from bald history into a creation that seems miraculous.