The History of Mechanics from the End of the 18th Century to the Middle of the 20th Century is the second collective monograph on the general history of mechanics, prepared at the Institute of the History of Natural Science and Technology of the USSR Academy of Sciences. Together with the previously published "History of Mechanics from Ancient Times to the End of the 18th Century," it covers the entire history of this important natural science until the middle of the 20th century. Both monographs are included in the General History of Natural Science prepared by the Institute.