8 



APPLIED SCIENCE 



of a scale prepared by the United States Geological Survey. 



It is kept at the Bureau of Standards, Washington, D. C. 



The foot is one-third of a yard, and the inch one thirty-sixth 



of a yard. 



The units of area and volume are the square and the cube 



of the unit of length, i.e., the square yard and the cubic yard. 

 The American unit of volume for liquids is the Winchester 



wine gallon, which contains 231 cu. in.* The British unit 

 is 277.274 cu. in. A quart is one- 

 fourth, a pint (Fig. 1) one-eighth, and 

 a gill one thirty-second of a gallon. 



The unit of weight, i.e., mass, is the 

 pound. This weight is based on the 

 force of attraction exerted by the earth 

 upon a block of platinum called a 

 pound weight. This block also is kept 

 in the Board of Trade office in Lon- 

 don. The United States standard 

 weight is the avoirdupois pound which 

 is copied from the English measure. 



11. Measurement of Distance. 



FIG. 1. Pint Graduate. 

 Graduated on right by 

 ounces, on left by frac- 

 tions of a pint. The Distances of a few feet are usually 



^Se s 1 ymboUorp I in e t r measured with the ordinary foot rule 

 graduated in inches, and in halves, 



quarters, eighths, and sixteenths of an inch. A carpenter's 

 wooden rule is made of boxwood, because of all woods this 

 is affected least by climatic conditions. Machinists' rules 

 (Fig. 2) are usually made of hardened steel and are graduated 

 to a fine degree. 



* The unit by which gas is measured is the cubic foot. The unit 

 by which building materials are measured is usually the cubic yard. 



