Blanchet - Poulin Cercle Hydrographique 196
Lefebvre-Poulin and Blanchet-Poulin hydrographic reflecting circles.
Product details: Blanchet-Poulin Cercle Hydrographique | Blanchet-Poulin | Reflecting circle | Survey | Material: Aluminium
One of the rare finds is this hydrographic reflecting circle. According to the various (French) documents that I have found there were two different models of this sextant meant to replace the previous but much more expensive 'classic' cercle hydrographique (or circle sextant). Thanks to a later offer (through this site) I now have both types.
The instrument can measure up to 280 degrees left from the central setting ('straight ahead'). It is unusual in that it requires the operation to use the right hand for changing the angle. The rationale is that while using the right eye most of the 'higher' angles are available while when looking with the left eye (some) of the other angles are available. However even with that, much of this range is unusable as either the observer will block the view ór there is not enough mirror left to actually see the reflected object. Angles up to around 130 degrees and then from around 190 to 230 degrees are however very well possible. The instrument does allow both an object in front and backwards to be aligned which was probably its most important function.
I have managed to buy two of them, the initial one is in rough condition and unfortunately only has the pinhole sight left and not the telescope. However, the newer one (which seems unused) has both all the accesoires with it. This includes the two filters which are placed on between the mirrors using a slot fitting the filter.
Blanchet-poulin survey circle 196
Data sheet
- Year
- c1967
- Serialnumber
- 960
- Type of use
- Survey
- Material
- Aluminium
- graduation
- deg
- diameter scale in mm
- 160
- Radius limb in mm
- 80
- fine reading
- drum micrometer
- Size instrument (l x w x h) in m
- 0.24 x 0.25 x 0.15
- weight instrument in kg
- 1.2
- Size case (l x w x h) in m
- 0.28 x 0.28 x 0.16
- weight case & in kg
- 1.8
- country obtained from
- France
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Lefebvre-Poulin and Blanchet-Poulin hydrographic reflecting circles.
Product details: Blanchet-Poulin Cercle Hydrographique | Blanchet-Poulin | Reflecting circle | Survey | Material: Aluminium