IN TIIO D UCTOR Y CHA P TEK. 



XXXV 



In the annexed woodcut a square inch and a square centimetre 

 are shown, in order to give an idea 

 of measures of surface which will 

 often be referred to in the following 

 pages. 



SQUARE INCH 



Unit of Capacity. The cubic inch, 

 foot, and yard furnish measures of 

 capacity ; but irregular measures, such 



as the pint and gallon, are also used in this countiy. The gallon 

 contains ten pounds avoirdupois weight of distilled water at 62 F. ; 

 the pint is one-eighth part of a gallon. The French unit of capacity 

 is the cubic decimetre or litre (\i-rpa, the name of a Greek standard 

 of quantity), equal to 1'7607 English pints, or 02200 English gallon ; 

 and we have cubic inches, decimetres, centimetres, and millimetres. 



61-027052 cubic inches. 

 28-315311 litres. 

 16"386175 cubic centimetres. 

 4-543457 litres. 



1 litre 



1 cubic foot 



1 cubic inch = 



1 gallon 



Unit of Mass or Weight. The English unit of weight the 

 pound is derived from the standard gallon, which contains 277*274 

 cubic inches ; the weight of one-tenth of this is the pound avoirdu- 

 pois, which is divided into 7,COO grains. The French measures of 

 weight are derived at once from the measures of capacity, by taking 

 the weight of cubic millimetres, centimetres, decimetres, or metres of 

 water at its maximum density, that is at 4 C. A cubic metre of 

 water is a tonne, a cubic decimetre a kilogramme, a cubic centimetre 

 a gramme, and a cubic millimetre a milligramme. 



