Sir Francis Head, when he saw one of the tubes raised, and in its place, observed, “It seemed surprising to us that by any arrangement of materials, it could possibly be made strong enough to support even itself,—­much less heavily laden trains of passengers and goods, flying through it, and actually passing each other in the air at railway speed.  And the more we called reason and reflection to our assistance, the more incomprehensible did the mystery practically appear; for the plate iron of which the aerial gallery is composed is literally not so thick as the lid, sides, and bottom which, by heartless contract, are required for an elm coffin 61/2 feet long, 21/4 wide, and 2 deep, of strength merely sufficient to carry the corpse of an emaciated pauper from the workhouse to his grave!  The covering of this iron passage, 1841 feet in length, is literally not thicker than the hide of an elephant; lastly, it is scarcely thicker than the bark of the good old English oak,—­and if this noble sovereign, notwithstanding ‘the heart’ and interior substance of which it boasts, is, even in the well-protected park in which it has been born and bred, often prostrated by the storm, how difficult is it to conceive that an attenuated aerial hollow beam, no thicker than its mere rind, should, by human science, be constructed strong enough to withstand, besides the weights rushing through it, the natural gales and artificial squalls of wind to which, throughout its entire length, and at its fearful height, it is permanently to be exposed.”

Notwithstanding these “incomprehensible” speculations, the tubes are abundantly strong to sustain the pressure of the heaviest trains, even were they to stand still in the middle of the bridge.  It is calculated that each tube, in its weakest part, would sustain a pressure of four or five thousand tons, “support a line of battle ship, with all her munitions and stores on board,” and “bear a line of locomotives covering the entire bridge.”  The bridge was completed, and the first train passed through it March 5th, 1850.  The total cost of this gigantic structure was only L601,865.

GLORY OF ANCIENT ROME.

Ancient Rome was built upon seven hills, which are now scarcely discoverable on account of the vast quantities of rubbish with which the valleys are filled.  Pliny estimates the circumference of the city in his time at 13,000 paces (which nearly agrees with modern measurements), and the population at 3,000,000.  Rome was filled with magnificent public edifices, temples, theatres, amphitheatres, circuses, naumachiae, porticos, basilicae, baths, gardens, triumphal arches, columns, sewers, aqueducts, sepulchres, public and private palaces, etc.