ANCIENT JjESEMERS OR STEELYARDS. 



5(U 



It was quite similar to the other two, ])ut weighed more exactly than 

 tht^ Clusium balance and ran up to 40 pounds. But both this and the 

 Palermo balance are far inferior in finish. The Clusium balance prob- 

 ably dates from the third or fourth century before Christ. 



Pernice's description of this balance on the archeological and metro- 

 logical sides is exhaustive. But as a member of the developmental 

 sei-ies of those balances called desemers, it then appears that a o-reat 

 technical advance is made over the instruments previously considered. 



Fu;. 2().^>r\iscuiu of GiTra;ui Costnnu 

 natural size. 



TuD-liltct'iiths 



I refer to the raising- of the bridge above the staff which carries the 

 load and counterpoise. Nothing like this has been seen in any of the 

 desemers ])i'eviously examined. Why did the Roman deface his ele- 

 gant instrument with this uiibeautiful bridged At first sight one might 

 be inclined to suppose that it was simply to make the num})ers show 

 betrer. But that hypothesis will not answer. The ])ridge, with the 

 sciil«\ might just as well have carried the load and counterpoise too. 

 There must have been some other reason, and a good reason there is. 



The two prime requisites of a 

 good balance are, as is well 

 known, that the friction shall be 

 as small as possible and that the 

 equilibrium shall be stal)le wheth- 

 er the balance is loaded or not. 

 The center of gravity nmst, for 

 that purpose. ])e below the point 

 of support.' 



Now German desemers, as we 

 know ])y experience, remain still 

 when in equilibrium without os- 

 cillating. They can not oscillate, 

 for the moment the departure 



from equilibrium is sufficient to overcome friction they turn, with no 

 tendency to return, and slide down on one side or the other, because 

 the point of support is below the center of gravity. If a pound is in 

 equilibrium on the desemer, and one side or other is pressed down. 



1 If it is too' far -teb^Mtt^lance will not be«ensitive enough; tfiat is, its position 

 of equilibrium will be t«o little changed by a small change of the weight m one j.an 

 If the renterof gravity is too close below the point of support, the oscillations an.l will, 

 them the whole operation of weighing will become slow and tedious. In tact, as 1. .ng 

 as the friction remains the same the excess of weight in one pan required to uvcr.nnu- 



-Koyal Ethnological Museum ol' IJrrlin. 

 One-.sixtl) natural size. 



