Thermometer - Gilt brass, Foamed silica

Antique double-scale wall thermometer in brass and wood (Réaumur / Celsius) – Second half of the 19th Century

Fascinating and rare antique double-scale wall thermometer dating to the second half of the 19th century (circa 1860–1890), in excellent original condition.
The instrument is a classic example of late-Victorian/Umbertine scientific-domestic manufacture. On the front there are two splendid monograms engraved in neo-Gothic calligraphic style: on the left the "R" for the Réaumur scale (freezing at 0°C, boiling at 80°C) and on the right the "C" for the Celsius/Centigrade scale. The coexistence of the two scales makes the object a valuable historical testimony of the transitional period toward the decimal metric system.

Constructive details and materials:
- Base: Rectangular, solid hard wood (ebonized dark), with elegant stepped perimetral molding. On the back is the original brass suspension ring for wall mounting.
- Front plate: Brass plate with finely incised numbers, marks, and monograms, filled with original black enamel. It shows a splendid and genuine patina of time (natural oxidation).
- Capillary and liquid: Mercury tube in hand-blown glass with a prism-shaped cross-section, milky white background to facilitate temperature reading. The mercury filament is intact and continuous.
- Metal details: Drive bands for the glass shaped with spear-point ends and a lower grille with horizontal slits to protect the bulb, all in brass.

Aesthetic and functional conditions:
The piece is presented in excellent condition (see photos). The glass is intact, with no cracks, and the mercury responds correctly to temperature changes. The patina of brass and wood has not been altered by restorations or aggressive polishing, preserving the collectible value of the piece. An anonymous instrument of great artisanal quality.
The included images (from the frontal overview to the monogram details and the back) are an integral part of the lot description.