Ancienne régle à calculs d'extrait sec des laits Tavernier-Gravet modèle Jean Pien Fourchettes à fondue There are some small stains

There are some small stains and the fabric is creased in places

The game is complete with its original instructions

all the pencils are present

the enamel is stained

Ancienne régle à calculs d'extrait sec des laits Tavernier-Gravet modèle Jean Pien Fourchettes à fondue There are some small stainsOld 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