girdsers and machinery, armaments, american naval power, even those civil war, the great battle of merrimac, the armor. so it's economically important, it's kind of symbolically important. kind of the great age of iron. you think of the eiffel tower, which is made of iron, bolted together. the great symbol of the new age, and i think many countries, including the united states, come to believe that you can't have kind of full sovereignty and autonomy as a nation unless you have an iron and steel destroy it and become this biggest-the coast capitalized industry in the united states, and out of it grows kinds of fortunes that had never been seen in this country before. carnegie and eventually comes the morgans, combines, and so it is symbolic and just kind of technically and necessarily to the new nation, and the scale of these places is amazing. just gigantic. >> with regard to the rise of steel and machinery, one thing that is what is eye-opening for me, we hear about the crystal palace and the beginning of world affairs but had not realized what was the main purpose of the world fair to in