Final answer:
The first machine-powered submarine built in 1859 was likely powered by a steam engine, as steam technology was prevalent and effective for marine propulsion during that period.
Step-by-step explanation:
The First Machine-Powered Submarine's Engine
In 1859, the first machine-powered submarine was built by two French inventors. While the provided information does not explicitly state the precise engine used in that particular submarine, it does describe the importance of the steam engine during that era. The steam engine was a critical invention that drove the Industrial Revolution and powered the first significant steamships and locomotives. As one of the first steam patents was granted in 1606 and Robert Fulton effectively used a steam engine on the Clermont in 1807 for commercial steamboat service, it is likely that the submarine in question was powered by an engine that used steam technology, as similar technologies were prevalent and had proven effective for marine propulsion.Based on the information provided about the development of steam-powered boats and the later use of batteries in German U-boats, we can deduce that the French submarine was most likely powered by a steam engine, given the technology of the time and the absence of practical electrical batteries for such purposes until the 20th century.