Barometers Realm

The instrument is housed in a leather case made from vegetable-tanned calf or bull hide (treated with natural tannins such as bark, gallnuts, etc.). The leather has a warm, light brown tone with darkened areas due to age and oxidation—characteristic of genuine vegetable-tanned leather. The case features machine stitching with thick waxed thread.

The altimeter’s body is made of anodized aluminum. Its dial is mounted on an enameled metal base, protected by a flat plastic crystal. The dial background is matte white, offering excellent contrast and legibility. It contains four concentric rings, each intended to be read using a single needle.

• The innermost ring is marked from 0 to 1000 meters, with 10-meter intervals and fine divisions down to one meter—designed for small elevation ranges. The markings are large and easy to read.
• The second ring is calibrated up to 2100 meters, also in 10-meter increments.
• The third ring covers the range from 2200 to 3500 meters, representing another +1000-meter segment.
• Finally, the fourth ring spans 3600 to 5000 meters, with the same scale step.

Beneath the scale area, a rectangular window marked “+ / –” displays the spring tension indicator, which assists in “zeroing” the mechanism—showing when the pointer has returned to its starting position. This visual guide helps the operator determine the current tension range setting.

The chrome wheel in the center of the altimeter adjusts the spring. In the classic Paulin system, this mechanism brings the entire internal structure into balance. After equilibrium is achieved, the pointer’s position is read on the appropriate ring. Slightly offset from the knurled control knob is a chrome spirit level.

The dial also states the instrument model: MM-1. Additional markings include:

• “MADE IN U.S.A. BY AMERICAN PAULIN SYSTEM, LOS ANGELES CALIFORNIA” across the top,
• And in the center, the company’s later logo, a stylized circle featuring the word “MICRO” in a central frame, surrounded by the phrase “SURVEYING MICRO ALTIMETER.” This logo was used in the company’s later years, distinguishing it from the earlier “PAULIN SYSTEM” double-frame logo seen in the 1920s–40s.

At the heart of this unique instrument lies the “zero point” principle. Its goal is to eliminate the mechanical interference caused by friction in conventional barometric systems.

The system is composed of two sensitive Vidie capsules, mounted on a solid base and connected to a rigid spring. The C-shaped main spring transfers force from the capsules. Expansion and compression of the capsules are limited by a crossbar mounted between two vertical posts. This restriction of capsule wall movement is a core innovation of the Paulin System, significantly reducing hysteresis—the characteristic lag in conventional aneroids between actual pressure changes and needle response.

The chrome knurled knob at the center of the dial is a micrometer screw, which increases or decreases the spring’s tension. It is used for measuring atmospheric pressure or altitude: while turning the knob, the operator adjusts the spring until its tension perfectly balances the atmospheric force acting on the capsule. This rotation moves a deeper disc mechanism, linked to a long, thin indicator needle, whose sharp tip is visible near the dial base, above an anti-parallax mirror. The needle’s angular position becomes a measure of atmospheric pressure. If its tip aligns with the pre-set zero mark between the “+” and “–” signs, the measuring unit is in perfect equilibrium—capsules centered, spring tension balanced. At that point, the barometric or altimetric value can be read from the large rotating hand linked to the adjustment knob.

To eliminate friction between the sensitive capsule system and the floating needle, the needle is suspended on a system of phosphor bronze bands and two spiral springs, allowing nearly weightless movement. To suppress oscillation, the tip of the floating pointer—acting as a counterweight—is immersed in a small reservoir of thick damping fluid, preventing needle flutter.

Additionally, the control knob houses a planetary gear mechanism that enables extremely precise calibration—a full rotation of the needle occurs only after sixteen turns of the knob.

A small but elegant accessory to the altimeter is a loupe in a Deco-meets-Engineering style. Based on its color, semi-translucent swirls, and signature sheen, it appears to be made of phenolic resin, most likely Bakelite, which often exhibits a marbled pattern due to uneven curing of resin and filler. On the loupe’s back side is a diamond-cut grip pattern—not merely decorative but functional, ensuring a non-slip hold. Items like this were never made “just because.” It reflects a classic design ethos of the time: even auxiliary tools were expected to be aesthetic, ergonomic, and durable. What we might call today a case of “remarkable, unnecessary craftsmanship.”