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Structure of mechanism |
| Function |
This is a precision scale. The instrument comprises a horizontal beam, which oscillates on a knife-edge which is in fact a steel prism. This knife-edge is part of the beam. At each extremity of the beam is another knife-edge (facing upwards) on which is suspended a staple supporting two pans. Two nuts on threaded shafts enable the balance adjustment of the mobile parts. A very long needle fixed to the middle of the beam, facing downwards, moves in front of a very small graduated rule to facilitate the monitoring of the equilibrium. On the top of the beam there is a graduated scale facing a metal rod which comes out though a hole in one of the glass panels. This rod carries the marked weights which can be placed on the beam to increase weighing precision. On the front of the apparatus is a screw which is used to raise the beam off the knife-edge fulcrum. This avoids unnecessary wear when the scale is not in use. There is a spirit level on the marble base. The instrument is protected by a glass case with a wooden frame, to avoid the influence of air movements which could affect the precision of the weighing process. The front panel slides open to give access to the scale. |
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Application |
| Examples of application |
The device is used to weigh light objects, principally in the fields of pharmacy of chemistry. It was used by future teachers during their studies at the men’s and women’s teacher training colleges, now the IUFM (University Teacher Training Institute) in Clermont-Ferrand. |
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