TWO protractor ampules brass, approximately 1880

The range of measurement of angles by both angles is 0 ... 90 angular degrees at a division angle of 0.1 degrees.

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TWO protractor ampules brass, approximately 1880
Goniometers do not have any markings, so it is difficult to determine the manufacturer and date of production, but brass ampules goniometers were produced in the late 19th century for literature.
Two goniometers are slightly different of brass beams, rotary brass arcs, cylindrical brass holders and glass ampules, while the overall dimensions of the goniometers, the length of the brass beams and the radii of the rotary arcs are the same.
The range of measurement of angles by both angles is 0 ... 90 angular degrees at a division angle of 0.1 degrees.
Glass ampules are 45 mm and 48 mm long.
Ampules goniometers differ in the way they measure angles:
- a more massive protractor does not have a vernier scale, the angles are counted using a scale on a glass ampule (10 divisions) with a division angle of 0.1 degrees;
- a less massive goniometer has a vernier scale with a division price of 0.1 degrees