The primary difference between barter and currency systems is that a currency system uses an agreed-upon form of paper or coin money as an exchange system rather than directly trading goods and services through bartering.
Scientific innovations created jobs for Americans by that product going nation-wide. What that means, is that when someone's scientific innovation went nation wide, or even global, they wold have to build factories, and places to make and sell that product. With those new buildings, comes new jobs, and he economy is improved. Take Thomas Edison for example. He commercialized the light bulb. When it became popular, he build huge power plants to build his product. He had to have people build his product inside the power plant. Those new jobs were filled by Americans.
Any adult male could take part of the government and make decisions, and this helped make modern democracies because in modern democracies everyone can take part and make decisions.
