THE RULE OF THE ROAD 6 



o 



handle. With the late construction of the " cab " of the driver, the 

 needs of the right eye were accentuated because the engineer in looking 

 out of the window at his right hand is compelled to put no more than 

 his right eye out of the cab-window. If he put the left eye out of the 

 left-side window he would have to put the entire head out in order to 

 see with the right eye. Thus right-eyedness has unconsciously com- 

 pelled the driver to disuse the right hand for the naturally expert 

 work with the throttle-valve, in order that the greater danger may be 

 avoided that would follow both to the engineer and to his train, from 

 putting the whole head out of the left window of the cab. 



Among the many ocular problems of railway employees those relating 

 to deficient color-perception are of great importance, but equally great 

 are those regarding presbyopia or the failure of visual acuteness after 

 40 or 45 years of age, and especially should the diagnosis of right- 

 eyedness or left-eyedness be held of prime necessity. The left hand 

 may be allowed, somewhat against nature, to manage the throttle- 

 lever, but the right eye must be the absolute judge of signals, etc. 

 Undoubtedly there are a few hundred, at least,, of left-eyed engineers, 

 signalmen, etc., on our roads, and their disability for their peculiar 

 calling is greatly endangering lives and property. Nor should it be 

 forgotten that there are generally proportionally more left-eyed than 

 left-handed men. As trolley-car " gripmen " or engineers, chauffeurs 

 of automobiles, etc., the left-eyed are at only a slight disadvantage, be- 

 cause nothing is in front of their eyes to impede the dominant func- 

 tion of the right eye. Despite this fact the automobile chauffeur sits 

 on the right-hand seat, not only because of inherited custom, but again 

 that his right eye may have the slight advantage of position and 

 that his right hand may be free to use in almost every instant's emer- 

 gency. In our trolley cars and electric locomotives the all-important 

 brake is operated with the right hand. 



To epitomize, the resolution of the mysteries as to the origin of 

 right-handedness and the rule of the road may be made only by 

 grasping the phenomena as a whole, i. e., by massing the facts of the 

 entire history from prehistoric savage battle and barter to the expert 

 locomotive-engineer of to-day running a " limited " train at the rate of 

 a mile or more a minute on a two-track or four-track railway. Even the 

 cave men show that right-handedness was the rule in their time, and 

 spear-hand, shield-hand, gesture-language, digital-counting, and the 

 tally-stick, the world over, fixed the speech and writing and right- 

 hand brain-centers in the left half-brain — and, of course, those of the 

 left-hand and fingers in the right half-brain. War made up the life 

 and set all the fashions of beginning civilization, and war together 

 with narrow streets established the custom of right-hand passing, for 

 walkers, riders of horses, asses, mules, etc., and for drivers of all 



