During the past decade, research by oceanographic geophysicists which has led to the wide acceptance that continents drift about the face of the earth and to the concept of sea-floor spreading has culminated in an all-embracing theory known as 'plate tectonics.' This theory draws sea-floor spreading, continental drift, crustal structures, and world patterns of seismic and volcanic activity together as aspects of one coherent picture.
The word "nomogram," meaning the "law in graphical form," properly includes alignment diagrams, network charts, and many other graphical forms. By the 1950s, the term "nomogram" came to refer to alignment diagrams exclusively. In this first broad compiling of American nomograms, approximately seventeen hundred alignment diagrams, network charts, and other graphical forms from 97 technical journals are presented, conveniently indexed. Only those technical periodicals were searched which patently favored the publication of this type of diagram.