Heuer, "Autavia Chronograph", Ref. 7863C. Circa 1960's. Fine, water-resistant, stainless steel wristwatch with round button chronograph, date and register. MH bezel
Case: Three-body, polished and brushed, lapidated lugs, graduated bidirectional revolving black bezel for the decompression times, snap-on case back. Date window at 6.
Dial: Bicolor black and silver with baton indexes, outer minutes/seconds divisions, subsidiary guilloché dials for the seconds and the 30 minutes register. Luminous steel baton hands.
Movement: Cal. 7732, rhodium-plated, 17 jewels, straight- line lever escapement, monometallic balance, shock absorber, self-compensating flat balance spring.
Ref: 7863C MH bezel
Size: 40mm Thickness: 13mm
More about Heuer:
In 1968, Heuer redesigned the case used for the Autavia from a screw-back to a snap back compressor case. A compressor case was a patented case designed by Ervin Piquerez who sold these cases to a few watch manufactures, the compressor case has a unique seal construction which ensures water resistance through pressure on the gaskets and the crown. The principle is rather simple, deeper the watch was immersed, the more pressure on the case, the tighter the case and more water resistant the watch.
However, despite the new case, the Autavia retained its original water resistance of 100 meters or 330 ft. the case was larger at 40mm. There were a few (compressor case) Autavia references:
Reference 2446C: Black dial with 3 silver register fitted with Valjoux 72 movement.
Reference 7763C: Black dial with 2 silver register fitted with Valjoux 7730 movement.
Reference 7863C: Also known as "Autavia 30 Dato", black dial 3 silver register with date fitted with Valjoux 7730 movement.
Reference 2446C: GMT: Black dial with 3 silver subdial, with a red GMT hand, blue and red bezel with Valjoux 72-4. There are also different bezels : M (minutes), H (hours), MH (minute hour), T (tachymeter), P (diving), GMT.
This Autavia 30 Dato, which might be one of the rarest configuration of the compressor Autavia is in excellent condition with sharp faceted case, the bezel has started to slightly turn grey.