486 PHYSIOLOGICAL PHYSICS. [Chap. XL. 



metre. It is intended to be about a ten millionth 

 part of the distance along the surface of the earth 

 between the pole and the equator. But it also is 

 measured by a standard metre of platinum. The 

 metre standard was intended to be a universal stan- 

 dard ; and it is rapidly becoming the standard of 

 length for scientific use. The system of measurement 

 by means of the metre is called the metric system. 

 It is also applied, as we shall see, to the estimation 

 of weight. The metre is divided into tenths and 

 multiples of ten, and this method of division and sub- 

 division makes the system extremely convenient to 

 work with. 



One metre (1 m.) = 10 decimetres (10 dcm.) = 

 100 centimetres (100 cm.) = 1,000 millimetres 

 (1,000 mm.). 1,000 metres is 1 kilometre. 



One English inch * = 25-399 millimetres (i.e. 1 ram. = about 

 foot =304-792 [^thinch.) 



yard =914-376 



One metre contains 39*370432 inches 

 One kilometre 39370-43200 



(nearly 1093-6 yards). 



There are 1-60932 kilometres to the mile. 



Of the following scales (Fig. 198) the first shows 

 T ^th of a metre (1 dcm.), divided into centimetres (10), 

 and millimetres (100) ; the second shows English 

 inches and tenths. 



The STANDARD OF WEIGHT or mass is in Britain 

 the pound (avoirdupois), which is the weight of a 

 piece of platinum kept in the office of the Exchequer. 

 It contains 7,000 grains. One pound troy contains 

 5.760 grains. 



The French unit of mass is the weight of a cubic 

 decimetre of distilled water at 4 C. of temperature. 

 It is called a kilogramme. It contains 1,000 grammes, 



* One Paris inch 27 '069 mm. 



