WONDERS OF THE IRON MANUFACTORY.-The amount of iron produced in the United States is three hundred thousand tons; all of which, and much more, is consumed in this country. The amount of nails alone is supposed to be fifty thousand tons. Forty thousand casks or four million pounds, are annually made by the Boston Company. Suppose that the nails will average one hundred and sixty to a pound, the number here produced each working day, would be nearly two millions. This is supposed to be but the twenty-fifth part of the nail manufacture of the United States. It seems incredible that about fifty millions of nails are made, bought sold and used, every day, in the United States, yet such appears to be the fact.