Offered in this auction by Second Vintage A captivating piece of late 1960s horological innovation, this Longines Ultra-Chron represents the pinnacle of high-beat precision from a golden era of Swiss watchmaking. Designed to combat the rising threat of electronic watches, the Ultra-Chron was celebrated for its remarkable accuracy, a mechanical marvel of its time. Encased in a quintessential cushion profile with a vertically brushed finish, this particular chronometer-certified example is a masterclass in elegant, purpose-driven design. It stands as a testament to Longines' historical prowess in creating highly accurate, aesthetically enduring mechanical timepieces that continue to captivate modern collectors. Brand: Longines Model: Ultra-Chron Automatic Chronometer Reference Number: 8355 5 Serial Number: 51024812 Movement: Automatic Caliber 431 Dial: Vertically brushed silver dial with applied faceted indices and black inserts, exceptionally clean Case Size: 37 mm (excluding the crown) Case Material: Stainless Steel Production Year: 1970 Condition: Excellent vintage condition with sharp case lines and a highly preserved dial. Movement have been serviced recently and performs strongly. Dial and Hands The vertically brushed silver dial is a study in refined vintage elegance, presenting in exceptionally clean condition with minimal signs of age. It features an applied Longines winged hourglass logo beneath the twelve o'clock position, complemented by the distinctive applied jagged Ultra-Chron emblem above the six. The typography, including the cursive Automatic and serif CHRONOMETER text, remains crisp and fully intact. Hours are marked by applied faceted baton indices featuring central black inserts, which harmonize perfectly with the matching baton hands. A framed date aperture at three o'clock completes the balanced layout. The dial surface shows remarkable preservation, free from significant spotting, moisture damage, or discoloration, maintaining its original factory luster and an incredibly fresh appearance. Case and Crystal The 37mm stainless steel cushion case exemplifies the bold architectural styling of its era. The upper case surface showcases a strong, factory-correct vertical brushing that transitions sharply into the polished flanks, indicating outstanding preservation of the original case geometry. The original Longines-signed crown sits flush against the case side. The screw-down caseback is adorned with the engraved Ultra-Chron medallion, remaining highly legible with honest signs of wear consistent with careful use. The inner caseback is properly stamped with the 8355 5 reference. The watch is fitted with a domed acrylic crystal that provides clear, distortion-free viewing of the dial, showing only light superficial handling marks appropriate for its vintage nature. Movement Beating at the heart of this timepiece is the legendary Longines Caliber 431, a high-frequency automatic movement operating at 36,000 vibrations per hour. The movement is proudly stamped with its caliber designation, the 36,000 bph mark, and the serial number 51024812. The rotor and bridges display fine finishing, with clear engravings denoting its 25 jewels and chronometer-grade adjustment to four positions and temperature. Exhibiting remarkable accuracy and consistency, performing brilliantly for a vintage timepiece. The timegrapher records a deviation of +2 to +8 seconds per day with strong amplitude. Movement have been serviced and performs strongly. Strap The watch is presented on its original stainless steel mesh bracelet, which perfectly complements the cushion case design. The endlinks are correctly stamped 8355, matching the interior caseback reference. The bracelet is secured by a distinctive clasp featuring an applied gold-toned Longines winged hourglass logo, adding a touch of warmth to the all-steel aesthetic. The mesh remains supple and structurally sound, accommodating a wrist size of up to 18.5cm with comfortable articulation. Condition This Longines Ultra-Chron is in excellent vintage condition. The dial is exceptionally well-preserved, showing virtually no deterioration, while the case retains its crisp factory brushing and sharp transitions between the top and sides. The caseback medallion is distinct, and the movement is visually clean and running with outstanding precision. The original signed bracelet shows normal, honest wear while maintaining its structural integrity and visual appeal. Dimensions Case Size: 37 mm (excluding the crown) Wrist Size: 18.5 cm Remarks This chronometer-certified Ultra-Chron is a superb example of high-beat horology, offering collectors a rare opportunity to acquire a mechanically superior and aesthetically striking vintage Longines. Its combination of a high-frequency movement, original signed mesh bracelet, and immaculate dial makes it a standout addition to any serious collection. History Introduced in 1967 to commemorate Longines' 100th anniversary, the Ultra-Chron was a bold statement in the pursuit of mechanical perfection. At a time when the industry was exploring electronic alternatives, Longines doubled down on traditional watchmaking by developing the high-beat Caliber 431, oscillating at 36,000 vibrations per hour. This rapid frequency allowed for unprecedented stability and accuracy, earning the Ultra-Chron its reputation as one of the most precise automatic watches of its time. The model line became a symbol of Longines' technical mastery and remains highly coveted by vintage enthusiasts who appreciate true mechanical innovation. Payment and Shipping Payment must be completed within 1–3 days after purchase. Your watch will be professionally and very securely packaged, and shipped with tracking and insurance for your peace of mind. We ship via fast express service, with typical delivery in 1–4 business days (destination dependent). Note that with vintage watches, minor signs of wear, aging, or imperfections may be present and are considered normal for watches of this age. Please review all photos carefully before bidding. We strive to photograph each watch from multiple angles for the most accurate representation. The photos form an important part of the description. If there are any concerns of functionality or defects after delivery, make sure to contact us within 3 days of receiving the watch so we can assist you. As with all vintage watches, water resistance is not guaranteed. If you have any questions, feel free to contact us after the auction ends. / Second Vintage SKU: LON-LAC-0001