Swiss heavy 1/10th split second chronograph Circa 1965

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.
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Diameter: 66 mm
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Weight: 298 g
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Signed: Longines