10. Agricultural mechanization, releasing the slaves and revolutionizing production
Perhaps one of the greatest benefits to mankind of the development of steam power was to make redundant the institution of slavery, paving the way for an abolitionist movement that certainly would have made no headway if there had been no alternative. Of course, mechanized agriculture preceded steam by centuries, and long before steam power, there was animal power, and even something as fundamental as a plough could be regarded as mechanization.
Animal power, however, did drive early reaping and threshing machines, but these devices were engineered and came about more or less in parallel to steam, and horsepower was phased out very quickly. The adaptability of steam power in terms of machines to plant and reap and thresh far exceeded human or animal power, and the reliability, and complexity of mechanisms have in the modern age almost entirely superseded the labor of man and beast. The most important result, however, has been a massive increase in agricultural production with a fraction of the labor input. Needless to say, this has helped drive the population explosion, and to sustain a population that could never realistically exist under conditions of cottage industry.
So we have it. Mechanized agriculture was undoubtedly one of the great engineering and technological advances of the age.