56 LECTURES TO SCIENCE TE AGREES. 



pan over the beam, and thus bring its point of suspension 

 nearer the centre of motion. There are few of the poorer 

 purchasers who either perceive or understand this act and its 

 result. But you will see that if the beam be sixteen inches 

 long and the chain is thrown over a point two inches nearer 

 the centre of motion, the effect must be to diminish the 

 weighing power of any weights placed in the pan by one- 

 fourth, and to defraud the purchaser to this extent in the 

 weight of the goods sold to him. 



A similar fraud is sometimes practised by butchers, with 

 equal-armed balances having a hook at each end to suspend 

 the pans. On bending the hook from which the weights are 

 suspended inwards, the weighing power of these weights is 

 diminished with a result similar to that already shown ; and 

 again, by bending the other hook outwards, and thus lengthen- 

 ing this end of the lever, a piece of meat actually weighing 

 4 Ibs. may be made apparently to weigh 5 Ibs. In our col- 

 lection at the Standards Office, we have a fraudulent beam 

 of this description which was seized from a butcher by an 

 inspector of weights and measures, and I have brought it here 

 to show it to you. 



I may also here mention another form of equal- armed 

 balance, much used both in this country and abroad, where 

 the pans are placed above the beam and knife-edges, which 

 are jointed together. If these balances are not properly con- 

 structed they also open a wide gap to fraud. I could show 

 you a balance of this description which has been deposited at 

 the Standards Office, where a 1 Ib. weight placed in the centre 

 of the goods pan exactly counterpoises a 1 Ib. weight in the 

 weight pan. But if placed at the inside edge it is 1J oz. 

 against the purchaser, whilst if placed on the outside edge it 

 is in favour of a buyer 1J oz. A dealer may thus gain 2| 

 oz. in every 16 ozs. in the quantity of a commodity that he 

 buys and sells again, though weighed in the same balance 

 and with the same weights. 



14. In further illustration of these principles of construc- 

 tion of a good equal-armed balance, the actual construction of 

 the several parts of the balance will now be explained. The 

 fulcrum on which the beam of the balance rests and turns at 

 its centre of motion is a horizontal plane of polished steel or 

 agate supported on the column of the balance. The beam 

 rests upon this fulcrum or bearing by means of a knife-edge 





