(from preface)

The aircraft, the printing plant, and the meteorological station, are each systems containing many machines. The mode of co-action is quite complex and very specific—in each case achieving a particular over-all result. To study or describe any one of these systems, we may proceed to analyze this complexity of interaction by taking for granted the "simple" existence of the elements such as the aircraft engine, the printing machine, the chronometer, etc. Of course, each of these is itself a complicated mechanism, containing many "simpler" elements, like wheels, rods, pulleys, etc. To a large extent the elements are not dissimilar, but the mode of interplay is again complex, and differs in each machine in achieving its specific objective.