The second industrial revolution is also called the second phase of the industrial revolution, since from a technological and a social point of view there is no clean break between the two revolutions. Many crucial inventions such as the Bessemer and the Siemens steel making processes were invented in the decades preceding 1871. One of the most crucial inventions for the communication of technical ideas in this period was the steam powered rotary printing press which was in fact a technological gift of the last decades of the first industrial revolution or first phase of the industrial revolution. The beginnings of wars offer a convenient milestone, since they have an impact on the capital needed to finance the useful application of new inventions.
One might see the immediate beginnings of this period in the German annexation of Lorraine (an industrial area) following the Franco-Prussian War. In any case, Germany came to replace Great Britain as the world's primary industrial nation. This occurred as a result of three factors:
In the United States of America the Second Industrial Revolution is commonly associated with electrification as pioneered by Thomas Alva Edison and scientific management as applied by Frederick Winslow Taylor.
Inventions and their applications were much more diffuse in this Revolution (or phase of a revolution) than earlier. The useful Steam engine was developed and applied in Great Britain during the 18th century and only slowly exported to Europe and the rest of the world during the 19th century, along with the industrial revolution. In contrast, practical developments of the internal-combustion engine appeared in several industrialized countries and the exchange of ideas was much faster.
To give but one example, the first practical internal-combustion engine ran on clean burning natural gas or coal gas and was developed in France by Etienne Lenoir, where it had a certain limited success as a stationary engine in light industry. It was tried out as a motive force for primitive automobiles in France in the 1870s, but it never was produced in quantity. It was Gottlieb Daimler of Germany who really exploited the breakthrough of using petroleum instead of natural gas or coal gas as a fuel, for the automobile a few years later. Then it was Henry Ford of the United States who, still later, exploited breakthroughs in the field of precise interchangeable parts and made the internal combustion engine a mass market phenomenon with a tremendous impact on society.
The end of the second industrial revolution or second phase of the industrial revolution has not been properly defined, since it would mean that the beginning of the third phase of the industrial revolution would also have to be considered. This is a difficult problem for the core of the industrial revolution is often linked to power sources and power usage. The first phase of the industrial revolution had coal or wood generated steam power at its core. The second phase of the industrial revolution had the internal combustion engine and electrical motors and generators at its core.
While some might surmise that the rise of nuclear power should mark the start of the third phase, it would clash with the fact that, with the exception of France, industrial economies depend less and less on nuclear power for their energy, and that, again with the exception of France, power from a nuclear reactor was never a major source of energy.