4 INTRODUCTION. 



TABLE 



OF SOME EQUIVALENT TEMPERATURES ACCORDING TO THE THERMOMETRIC 

 SCALES OF CELSIUS (CENTIGRADE) AND FAHRENHEIT. 



Formulae for the reduction of the Fahrenheit to the centigrade scale, 

 and vice versa. 



To reduce F. to C, subtract 33, multiply by 5, and divide by 9. To 

 reduce C. to F., multiply by 9, divide by 5, and add 33. 



1 C. equals 1.8 F. 1 F. equals .555 C. 



THE METRIC SYSTEM. 



§ 7. Definition. — The Metric System of Weights and Measures is based 

 upon the 7neter as a standard of length. 



The Meter. — This, the unit of length, equals, approximately, one ten- 

 millionth part of the quadrant of the meridian circle which passes through 

 Dunkirk and Barcelona ; it is thus about one forty-millionth part of the 

 earth's circumference as measured upon that line. 



In common English measure, the meter is 39.37079 inches, or about 

 3 feet 3 inches and a third, or about three and one third inches more than 

 a yard. 



The Liter. — This is the unit of capacity. It represents the space 

 occupied by a cube whose edge is one tenth of a meter. 



The liter corresponds nearly to our quart ; more accurately, it is 1.056 

 common quart; 0.880 imperial quart ; 0.907 dry quart. 



The Gram — This is the unit of weight. It represents the weight of a 

 cube of distilled water whose edge is one hundredth of a meter, and at a 

 temperature of 4° C. 



