Information for Compensated Recording Barometers (Barographs) Translated from the Naudet Dourde Baromètres Holostériques Catalogue of 1928

This is a literal translation of the Notice pour Baromètres Enregistreurs Compensés from page 10 of the Naudet Dourde Baromètres Holostériques catalogue of 1928. The image shows the preceding page 9, displaying a wood cased and a brass cased barograph, and with mention of Voir Notice au verso (see notice on the back):

The recording barometer (barograph) we have been building since 1900 has, thanks to the advantages derived from the principles underlying its design, earned a reputation equal to that of the ordinary barometers the company has been making since 1860. Its principle, based on the use of a curved spring in the shape of a swan’s neck holding apart the walls of a stack of vacuum boxes stacked on top of each other to balance atmospheric pressure, gives it an undeniable superiority.

The advantage of our system is that the operation of these boxes is performed in a uniform and regular manner, by the articulated connecting rod that connects them to the single spring that controls them and causes them to manoeuvre in the most perfect vertical direction, a result that cannot be achieved with the system of vacuum boxes, each containing a separately acting spring.

Aside from this superiority, our recorder also possesses that of compensation.

Since temperature compensation using the air enclosed in the vacuum boxes has been recognised as absolutely detrimental to the proper functioning of barometers due to the inequalities in elastic forces resulting from the heating of the air trapped in the tubes to different temperatures, we have been led to apply the same bimetallic compensation method used in the construction of chronometers and other good watch movements, which is based on a physical and mechanical principle whose value is no longer open to debate.

Finally, to make our instrument perfect, we have adapted the same setting as for our altimetric barometers, which allows us to achieve such precision that we do not fear comparison with the Fortin barometer.