Briefly, then, modern bridges everywhere are anti-social. When war is afoot, they imperil the best-made plans of strategists; and even in strikes they have to be guarded by soldiers, as if they were convents where dethroned queens lived unhappily with suffragette princesses. Though we have lived for many years on the brink of war, every highway in Europe as in America is at the mercy of bridge-wreckers. Is it not dumbfounding that no respect has been paid anywhere to the social guardianship that bridges and roads ought to perform? Why has this all-important matter been forgotten? It has been made memorable a great many times in history, ever since Horatius Cocles and his two companions held the Pons Sublicius against the whole Etruscan Army under Porsena,--a lesson never forgotten by Roman citizens. When Lord Surrey, before the battle of Flodden Field, outwitted the Scotch by throwing his army across the Till by the beautiful old Twizel Bridge; or when Charles the Second, routed at Worcester, fled by Old Pershore Bridge into the Bredon Hills, England received one of many warnings that a secure passage over rivers might be to her at any moment as valuable as an army corps. Why has she failed to take this lesson to heart? No railway is protected by two or three branch lines over an important river, so that two or three bridges--not near together, but separated by a mile or two--would have to be destroyed before the river would be closed to the passage of troops and of food supplies. Understudy lines and bridges would be invaluable to defensive strategy. More than a century has gone over since Perronet warned France that bridges across great rivers ought to be of a kind which would facilitate makeshift repairs after mishaps in war. He spoke earnestly, but in vain; for the conception of trade as war had not yet been forced upon the world by modernised industrialism, with its civil strikes and its international competitions. If Perronet had been able to add his foresight to the great traditions of the _Ponts et Chaussées_, his countrymen, probably, would have been loyal to his excellent advice, because the French have a Roman logic and they love their roads and bridges. But in France, as in other countries, a craze for engineering feats took possession of the public mind, excluding many other considerations. I know not how many perishable bridges exist at this moment in France, but I can give the figures for 1873. In that year there were one thousand nine hundred and eighty-two. Their total length was 106 kilometres, and their total cost was 286,507,761 francs. Here are some of the more expensive examples:--