A course delivered by the distinguished professor Ivan Avgustovich Time at the Mining Institute. The author compares hydraulic engines with steam engines. All advantages lie with the latter. Hydraulic engines require a specific type of terrain, climatic conditions, and their operation is inconsistent throughout the year, etc. Steam engines, on the contrary, can be installed anywhere; climatic conditions do not affect them; their operation is consistent; but along with these fundamental principles, steam engines also have an important drawback, namely the possibility of a steam boiler explosion.