This is a US Divers Company “Aqualung Calypso” diving gauge from the mid to late sixties. Having an affinity for anything sporting a needle under glass I just had to have one of these and therefore have been on the lookout for one at a good price. This particular gauge came by eBay for about twice what it would have cost new in 1966.
As is the case with just about every piece that graces the pages of this blog, it arrived in rough and scuffed condition although the case, which is chrome plated brass, is exceptional.
The crystal is a particularly thick acrylic which I suppose should be expected since the gauge is designed to be strapped to the wrist of a real scuba diver- and not to one of us “desk divers”. It’s also rated for immersion up to two hundred feet, which would have been quite a deep dive in the 1960’s!
Depth is measured by pressure differential using a bourdon tube. There’s s small opening on the side of the case for water to enter the tube. This opening can become obstructed by salt from ocean diving but is easily cleared via a prolonged bath in fresh water.
My Calpyso came with quite a large strap made of thick rubber which is secured to the case between the lugs with large threaded pins. The rubber here is also reinforced with steel tubing to keep it from tearing away from the case in the event of a snag.
Originally I intended to crack this thing open but to do so would require removing the crystal and if I break it I don’t think I could find a replacement. Instead I elected to just spiff it up with a bit of acrylic polish and clear the bourdon tube.
I removed the salt build-up by soaking the gauge for twenty-four hours in distilled water. Probably this didn’t clear the length of the tube but what was visible was noticeably clean following the bath.
I’m a big fan of acrylic crystals on watches because of how easy they are to polish up and this one was no different. I noticed a small crack to one side when I was done but otherwise it looks a heck of a lot better.
It was at this time that I discovered all the markers on the dial along with the logo are treated with luminous paint. At the time of manufacture this would have been either Tritium or Radium based paint. Neither typically ages well on watches (take a look at any Pierce watch I worked on earlier) but this paint looks like it was applied yesterday! Amazing how well it holds up in a hermetically sealed environment.
I suspected the luminous paint still had a bit of life in it and was not disappointed when I broke out the black light.
The paint even continues to glow for several minutes following a bit of exposure which is quite surprising considering its age.
I’d love to test the gauge in the wild but I’ve never had the ears required for deep diving. Perhaps I’ll take it to a dive shop just to check its accuracy though. In the meantime it’s another needle, dial, and glass for the collection.