Swiss heavy 1/10th split second chronograph Circa 1965

Kenmerk: BA3417
Diameter: 66 mm

Estimate: € 1.250 - 2.500
Price sold: € 1.950

Stainless steel Nonius split second chronograph
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A heavy Swiss stainless steel open faced precision split second chronograph, the Nonius, made by Longines, circa 1965. The polished case with a screwed on back. Silvered dial with Arabic hours, an outer minute track, 30 minute counter at 12 o’clock, constant seconds at 6, a white Arabic scale for tenth of a second timing, a yellow Vernier/Nonius scale from 0-9, an orange Nonius hand and black sword hands.

The rhodium plated 2/3 plate movement with Geneva striping decoration, a lever escapement, split second chronograph, high speed oscillator, the finest matted bevelled steel chronograph parts, a ratchet wheel, ground and bevelled double hand tong with a separate ratchet wheel for the split second chronograph, a going train with constant force, screw compensation balance, balance spring with inner terminal curve, an index spring fine adjusting device, a hack feature and shock protection for the balance.

Dial signed, case and movement signed and numbered.

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Diameter: 66 mm
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Signed: Longines
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Reference No. 8350.1
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The Longines Nonius was a valiant attempt in the late 1960s to crack the elusive puzzle of making the chronograph ever more accurate. The calibre 262 used in these watches has a frequency of 5 Hz, making 10^th of a second timing possible. In these chronographs, the Nonius hand is an orange central chronograph pointer with a curved extension indicating a scale from 0 to 9. It utilizes the principle of the Vernier scale.
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The Vernier scale, invented by Pierre Vernier, is a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation, which increases resolution and reduces measurement uncertainty by using Vernier acuity.
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The Vernier scale is also called a Nonius after Portuguese mathematician, cosmographer and professor Pedro Nunes. In English, this term was used until the end of the 18th century. Nonius now refers to an earlier instrument that Nunes developed.
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Pierre Vernier (1580-1637) was a French mathematician and instrument inventor.
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Pedro Nunes (Petrus Nonius in Latin) (1502-1578) was a Portuguese mathematician, cosmographer and professor.