The U-shaped capillary tube contains mercury in the lower part and alcohol in the rest of the tube and in the side reservoir. The Réaumur scale from -30 to +50 is indicated on the sides of the tube, with some particular values: 0 frost; 10 temperate; 25 bathing; 40 Senegal; 50 Syria.
The thermometer records the maximum and minimum temperatures reached during the day; the expansion of the alcohol in the reservoir forces the mercury to rise in the high temperature limb, pushing the cylinder that is in contact with the surface of the mercury and which remains in the position reached even when the mercury drops, thus indicating the maximum temperature. The contraction of alcohol due to a fall in temperature produces the same phenomenon in the opposite limb, indicating the minimum value reached during the day.
The thermometer is signed by its maker, Ing Pizzagalli, Milano and dated.

Device on display.