FUNDAMENTAL UNITS OF MEASURE.* 



By T. 0. Mendenhall, 



Stqjeriittendt'nt of the U. S. Coast aud Geodetic Siirren. 



Engineering is the art of construction; but to limit it to this would 

 be to restrict its meaning much within the range of the ordinary useot 

 the word. In a broader sense, engineering includes all operations whose 

 object is the utilization of the forces of nature in the interests of man. 

 It is both an art and a science, and as a science it consists for the most 

 X)art of mathematics applied to physics and mechanics. It is of neces- 

 sity, therefore, a measuring science, and a congress of engineers ought, 

 in the nature of things, to be interested in anything relating to progress 

 in metrology. 



Fortunately the literature of this subject is neither scanty nor difili- 

 cult of access. Much attention has been given to it in all parts of the 

 world during the hwst half of this century, and in the United States 

 especially numerous and valuable papers and reports upon the subject 

 of weights and measures have apj^eared during this period. Indeed, it 

 would be difficult, if not impossible, to contribute to either the historical 

 or the controversial aspect of the (question anything new aiul of notalde 

 value. 



In spite of an extensive and widely circulated literature, however, it 

 is very distiiu-tly in evidence that the origin and genesis of the units 

 of measure in customary use in the United States and among most Eng- 

 lish-speaking jjeople, and their relation or want of relation to each other, 

 are matters concerning which many engineers are not well informed. 



Perhaps not a large majority of members of the profession in good 

 standing would be able to answer accurately the question. What is a 

 yard? or What is a pound? In view of this fact no excuse need be 

 offered for presenting a statement of facts relating to fundamental 

 standards in this country at the j) resent time, and for the sake of clear- 

 ness this statement will be prefaced by a brief consideration of the 

 principles involved in the evolution and selection of standards, together 

 with a resume of genealogical history, showing their origin and ances- 



* Read before tlie luteriiatiouiil Engineering Congress of the ColiunT)ian Exposi- 

 tion, Cliicago, 1.S93. (From Transactions of the American Society of Civil Engineers, 

 October, 1893, pp. 120-134.) 



135 



