From Paris he wrote to Benjamin Vaughan, in 1787: “Mr.
I am sure it will gain, both in beauty and strength.
It is true that the divergence of those radii recurs as a difficulty, in getting the rails on upon the bolts; but I thought this fully removed by the answer you first gave me, when I suggested that difficulty, to wit, that you should place the rails first, and drive the bolts through them, and not, as I had imagined, place the bolts first, and put the rails on them.
I must doubt whether what you now suggest, will be as good as your first idea; to wit, to have every, rail split into two pieces longitudinally, so that there shall be but the halves of the holes in each, and then, to clamp the two halves together.
The solidity of this method cannot be equal to that of the solid rail, and it increases the suspicious parts of the whole machine, which, in a first experiment, ought to be rendered as few as possible.
He sailed in April, 1787, and landed in France, where he met with a warm welcome.
France was beginning to ferment, but the Revolution was undreamt of.So it was that Thomas Paine, alternately corset maker, exciseman, and agitator, fell athwart Benjamin Franklin while in London lobbying for better pay to collectors of revenue from spirits, and was persuaded to sail for our land of opportunity, where the Revolution was ripening. The pamphleteer had yet to be superseded by the journalist, and “Common Sense” electrified the colonies when it first appeared on January 10, 1776, half a year ahead of the Declaration.Here he arrived in due season, with a letter to Richard Bache, describing him as “an ingenious, worthy young man,” to whom the note brought more in the way of acquaintance than employment. If ever there was a loud note to kings and ministers, this was it!But of all this, the practical iron men are much better judges then we theorists. I find that the conclusions of his demonstrations are, that every part of the catenary is in perfect equilibrium.You hesitate between the catenary and portion of a circle. It is a great point, then, in a new experiment, to adopt the sole arch, where the pressure will be equally borne by every, point of it.To a generation that finds its greatest interest in Benjamin Franklin as the author of some advice on how to choose a mistress, it may come amiss to be reminded that the sage’s most important discovery was Thomas Paine, and that Paine’s most beneficial action was the invention of the iron bridge.Confirmed admirers of the workman, who became the first polemist of the eighteenth century, are apt to claim too much for him—especially when they allege that he inspired the Declaration of Independence, but they stop short of his chief achievement, tta building of the metal cross-over.The burning words of the pamphlet, and the series of “The Crisis,” need not be echoed.We know that the pen of the ex-stay-maker fired the patriot heart as did no other; that a wearied people rose again and again at his trumpet calls.It was thirty-four feet wide, with a span of two hundred and thirty-six feet—the father of all the great structures that now serve human convenience everywhere.The iron bridge greatly interested Thomas Jefferson.