Ancienne régle à calculs d'extrait sec des laits Tavernier-Gravet modèle Jean Pien Fourchettes à fondue There are a few barely

There are a few barely visible micro scratches on the bottom of the plates

With the arrival of domestic gas in kitchens

the enamel is stained

Il n'y aucune ébréchure

Ancienne régle à calculs d'extrait sec des laits Tavernier-Gravet modèle Jean Pien Fourchettes à fondue There are a few barelyOld ruler for calculating the dry extract of Tavernier Gravet milk, Jean Pien model. This model used in agriculture makes it possible to instantly obtain the total dry extract and the defatted dry extract of whole or skimmed milk. This very unusual slide rule model dates from after 1943. The ruler is in very good condition and its cardboard box is present. There are some small signs of yellowing on the plastic. The original instructions are missing. I