CHAP, i.] OSCILLATIONS OF THE PENDULUM. 



31 



comes to the same thing, the movement from the point A will be to 

 the movement from the point B in the same relation with the arms of 

 the lever A and o B. Hence it follows that the action of the weight 

 of the body, passed to B and A, is the same as if it were all exerted 

 at B ; so that weights will suffice ten times less heavy than that of 

 the body to be weighed to produce equilibrium. If the equilibrium, 

 for example, is established in standard weights with 5'4 kil., the 

 actual weight of the body is 54 kilogrammes. Balances of this kind, 

 with additions and improvements, are much used in luggage booking- 

 offices, railways, and warehouses. When it is necessary to weigh 

 carriages or loaded carts, they formerly used in France weighing- 

 bridges, a sort of balance the principle of which is analogous to that 

 of the balances of Quintenz, that is, it depends on a combination of 

 levers of different lengths. In some foreign countries they still use 

 weighing-bridges or the balances of Sanctorius (from the name of 

 the distinguished Italian to whom the invention is attributed). 



FIG. 11. Peson. 



FIG. 12. Letter weight. 



The peson is a form of steelyard, with immovable weight, used 

 for the weighing of light materials, letters for instance (in this case 

 it is called a letter-weight), or, in spinning factories for silk, wool, or 

 cotton. 



It is a lever, AB, made to turn round a point o. One of the arms, 

 A, carries a pan intended to receive the materials to be weighed. 

 At o is a needle fixed to the lever at a light angle. When there 

 is no weight in the scale, A B remains horizontal, and the needle 



