The adaptability which nature has bestowed on man has made it possible for him to attune himself to difficult situations. Modern machinery, provided with servomechanisms, working mechanically, hydraulically and pneumatically, has become a highly perfected instrument. However, the man who operates a machine, as tribute to human ingenuity, must often work under more difficult conditions than the machine he handles. To attain a high efficiency it is essential that the combination man-machine shall constitute a well integrated unit, and this involves considerable mutual adaptability. Hence human engineering must make an ever increasing effort to adapt the conditions under which man must work to his own physical needs, so that he can carry out...