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T117-24 · Pocket
late 19th century
Object Overview
This unique late 19th-century Engineer-surveyor set in a double-sided case by Henri Morin comprises four devices: a barometer, a thermometer, a compass, and a sight, all concealed within a minimalist case. Such sets are also known as the Alpine Altimeter Set.
The wooden case is covered with leather and lined inside with soft green padding to prevent damage to the instruments. The case features two hinged lids on each side with a simple locking mechanism. It also has two leather straps for secure carrying.
Aneroid Barometer. The barometer's casing is made of black-painted metal and is partially recessed into the protective shell. On the exterior, there is a rotating knurled bezel fitted with a flat, beveled-edge glass. Inside the bezel, a thin silver-plated reflective ring and a needle-shaped trend indicator are situated.
The barometer’s dial is crafted from silver-plated brass and features two scales. The barometric scale, engraved in centimeters of mercury, ranges from 44 to 78 centimeters. There is no standard text weather indication present. The second scale, located inside the circle, is an altitude scale. Unlike traditional altitude scales calibrated in feet or meters, this scale is marked in hectometers (1 hectometer = 100 meters) and is engraved in numbers ranging from 0 to 48 to save space. To determine altitude, simply add two zeros to any of the numbers. The altimeter's limit is 4800 meters.
n/a
rack and pinion
chrome, glass, leather, nickel silver, silvered brass, steel
If you look closely, you can see that the altitude scale of this essentially altimetric barometer is nonlinear. The divisions between unit marks from 0 m to approximately half of the scale are distinguishable, but in the range up to 4800 m, they become almost indistinguishable. The numerical markings on the right side of the scale are crowded together, practically merging into a single row (which is why hectometers are used). Such instruments can accurately measure height differences and are therefore ideal tools for surveyors and engineers. Measurements are taken at any points of interest, recorded, and later converted into elevation values in the office. When measuring slopes or inclines, the recorded values can be used directly, as in this case, only the differences between readings matter, regardless of changes in air pressure.
The barometer is based on a conventional continental cantilever mechanism with a rack-and-pinion system (Fig. 10, 11).
Mercury Thermometer. The barometer is mounted onto a silver-plated brass plate, slightly offset from which a thermometer is also installed. The small glass thermometer tube is fixed to the silver-plated brass plate with a metal wire. The centigrade scale is engraved directly onto the plate and is duplicated on both sides of the thermometer tube.
Bearing Compass. The compass casing is made of black-painted metal and features thick flat glass with beveled edges. The black dial, with contrasting silver markings, displays the cardinal directions: N (North), S (South), E (East), and W (West), as well as intermediate directions: NE (Northeast), SE (Southeast), SW (Southwest), and NW (Northwest). The compass needle is crafted from steel and blued on one side to indicate north.
A sapphire stone, positioned at the center, serves as the pivot bearing for the compass needle. Sapphire, a variety of corundum, is exceptionally hard (9 on the Mohs scale), making it ideal for precision instruments. It is resistant to corrosion and maintains its properties in harsh conditions. The sapphire provides a minimal contact point for the needle, significantly reducing friction and ensuring smooth rotation. This feature is especially critical for compasses used in precise navigation, such as marine or aviation purposes, as well as for geodetic applications.
A small metal lever on the exterior of the case acts as a locking mechanism to secure the needle when not in use.
The compass card, a fixed ring engraved with degree markings, is made of silver-plated brass and divided into 360 degrees with 10-degree intervals.
Sight. Adjacent to the compass is a device that is part of the navigational equipment — a sight (or aiming device) used in conjunction with the compass. Its purpose is to accurately determine the direction to an object. The sight enables precise alignment with distant landmarks, such as buildings, mountain peaks, ships, or other points of reference.
The sight is made of metal and features two folding plates on either side: one plate has a narrow aperture, while the other has a wider opening with a thread or reticle. These plates are used for precise aiming at a target. Once aligned with the object, you look at the compass to read the azimuth (the angle between the north direction and the target direction) or the bearing in degrees. Sights are commonly used in handheld compasses for taking bearings in field conditions.
The bearing compass and the sight are mounted on a plate made of silver-plated brass.
Henri Morin founded the company Ateliers H. Morin around 1880 in Paris. The company quickly became one of the leading French manufacturers of drafting, surveying, and artillery instruments. H. Morin specialized in producing a variety of scientific and measuring tools. The company offered a wide range of instruments, including theodolites, levels, compasses, barometers, and other devices for surveying and engineering work.
Their barometers were renowned for their high quality and precision, making them popular among engineers, researchers, and other professionals of the time. In 1905, Georges Boyelle joined the company as a director and partner, and by 1930, the name Paul Beau appeared in its catalogs. The company registered patents under the names Morin, Boyelle, and Beau. Two workshop addresses are known: 3 rue Boursault and 11 rue Dulong in the 17th arrondissement of Paris. In the 1960s, the Morin company acquired Secrétan, which belonged to the Legros family in Cachan at 44 rue Etienne Dolet. Later, it merged with SERPI, also located in Cachan.