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Structure of mechanism |
| Function |
This device is housed in a wooden case, and is composed of a sighting telescope with an object lens and an eyepiece. A screw enables the image to be focused. The telescope is attached to a vertical armature featuring, next to the eyepiece, a circle arc divided into tangents with graduations from 0 to 200. A magnifying glass fixed to this armature enables the circle arc graduations to be read with precision. The telescope can pivot in the vertical plane in order to measure the slope.
This rotation can be blocked by a screw. The telescope is fixed to a first circular plate which can turn in the horizontal plane. On its upper surface are two verniers from 0 to 50. A second plate located outside the first can turn independently. On its upper face are graduations for each degree, from 0 to 400 graduations. A vice closed by a screw in the upper part enables these two parts to be locked together when required. Below and connected to the second plate is another disc which can turn independently of the base. As before, a vice closed by a screw in the lower part can lock the two parts together if required. The base has three footscrews to adjust the horizontal level. This is verified by a spirit level in a brass tube which is located on the first plate.
For each measurement it is necessary to verify that the device, fixed to a tripod, is horizontal. This is done using the footscrews and the spirit level. The device is used for sightings and angle measurements in the horizontal plane. The vertical arc of circle is divided into tangents, and gives the slope by metre per target graduation. The device is used in topography for terrain surveying or building construction. It measures the slopes of various points indirectly, with the help of a target. |
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Guidance function |
| Trace of a dedicated point on follower |
 Open trace |
| Dimension of mechanism |
spatial |
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