Gherzi Psychrometer humidity slide rule textile 1950 Switzerland

This is a very specific slide rule for calculating textile humidity and related temperatures. It was made by and patented for the Gherzi Textil Origanisation in Zürich Switzerland. Guesstimating in the 1950’s. Inside folding out and swiveling are the 2 thermometers. One for the room temperature the other for the temperature of the cloth. With the slide rule on top (the Psychrometer) the humidity can be calculated. It is completely made of metal, no expenses spared and it comes in a dedicated heavy duty signs leather case. It is still in great condition and does not show to many signs of use or age. Beautiful piece of textiel history and dedicated slide rule use. It measures ca. 22,5 cm or ca. 9 inches long. Check the attached video on how to work your vintage man tool : slide rule operation instructions!