Negretti & Zambra Mining Borehole Thermometer

Negretti & Zambra Mining Borehole Thermometer

Negretti & Zambra Mining Borehole Thermometer.
This instrument is what is believed to be a mining borehole thermometer. The glass mercury filled thermometer tube is encased in a cut-away brass tube with a screw top and suspension hanger. The bottom of the brass tube is pierced around the area where the mercury reservoir sits.   

Made from brass and glass. Size 11″ x 3/8″ inch.

The back of the glass thermometer tube is etched with the makers name as Negretti & Zambra Ltd. The company went limited in 1948. 

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