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Structure of mechanism |
| Function |
This scale, made entirely of brass, comprises a horizontal beam, the centre of which rests on a knife-edge (a steel prism) attached to the beam. A screw at the base of the column enables the beam to be blocked or freed as necessary, to avoid unnecessary wear when the scale is not in use. At each end of the beam is a stirrup which holds a pan. Each pan features a hook, from which objects can be suspended and then immersed in a liquid.
The main support has a spirit level in its base, enabling the scale to be positioned horizontally by the adjustment of three screws in its feet. A long needle moves in front of a small rule attached to the vertical support. |
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Application |
| Examples of application |
This scale enables the demonstration that Archimedes’ thrust, which acts on an object immersed in a liquid, is equal to the weight of the liquid displaced. The principle consists of attaching an object, immersing it in a recipient filled with water, and determining the weight by bringing the beam’s needle back into the vertical position by adding weights to the other pan.
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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