30 THE APPLICATIONS OF PHYSICAL FORCES. [BOOK r. 



this point one kilogramme is marked. The space comprised between 

 o and i, divided into decimal divisions and continued along the large 

 arm of the beam, gives the graduation. This is a useful balance, 

 as it does not require the use of a series of standard weights, and 

 weighs large bodies with ease when an exact result is not neces- 

 sary. It is not very delicate ; its use is legally authorized in France 

 only when it does not fail to indicate an excess of weight as much 

 as the 500th part of its maximum load. 



The weighing machine or the Quintenz balance (named after its 

 inventor) is based on the same principle as the Boman steelyard the 

 body to be weighed and the weights acting at the extremity of the 

 unequal arms of the lever. But there is this difference : the two 

 arms are of invariable lengths, and it is at the extremity of the 



FIG. 10. Weighing machine or Quintenz balance. 



shorter arm that the body to be weighed is placed. The Quintenz 

 balance then requires, like the ordinary balances, a series of weights ; 

 but these weights are less than those of the objects : for instance, if 

 the relation of the levers OB and OA is that of 1 to 10, equilibrium 

 will be obtained with heavy bodies by means of standard weights 

 of one-tenth the weight. 



The platform D E, on which the body to be weighed is placed, 

 rests by a horizontal edge I on a piece K L forming a movable lever 

 round K, and acting by the elbow L A on the arm o A of the beam. 

 The distances I K and K L being made proportional to o B and 

 OA, it follows from this arrangement that the platform DE, hori- 

 zontal before the heavy body is placed on it, will remain horizontal 

 when that body by its weight will cause it to give way, or, which 



