Recently, a vintage Swiss Army watch that defies logic has been popping up in my eBay searches. At first glance, the Victorinox Swiss Army 9G-500 Automatic seems to be a standard 3-hand pilot style watch. It is only when we look closely at the design do things get really interesting…err, make that confusing. This is when you notice that the chapter ring has a very unusual scale printed on it. Swiss Army’s 9G-500 chapter ring scale is not designed for a typical tachymeter, telemeter, pulsometer, fuel gauge or slide rule calculator. Instead, it is a numeric scale that inexplicably goes from 0-to-100. This is not something you see that often. What in the world is going on here?
Victorinox Swiss Army (Swiss Air Force) 9G-500. Photo: Brian A.
I was not the person who first noticed this chapter ring with the odd 0-to-100 scale. My buddy, Brian A., sent me a photo and asked: “what do you think that bezel is for?” I was prepared to school him with a canned answer of “Oh, that is a tachymeter used to determine speed over a given distance”. Instead of this snarky retort, he was met with an emoji of a blankly staring face that mimed “I am shocked and I don’t know!” This mysterious bezel was quite unexpected. I thought that I had seen it all, but apparently, that is not true. I had seen this watch before, but I never noticed this unusual feature.
A good looking automatic watch with a mysterious back story
Vintage Victorinox Swiss Army rarely embellishes a watch for the sake of style and not function. That stylistic practice is often looked down upon by watch collectors because many fashion brands add doo-dads to a watch’s dial that simply do not belong nor make sense in the context of the watch’s purpose. This would be like adding fake chronograph subdials on a time-only watch. Describing a timepiece as a “fashion watch” is not a compliment, but maybe it fits here. Or, that is what I thought at first.
The 0-to-100 chapter ring markers do not align with the dial indices because they are based on increments 0-to-60. Photo: Brian A.
I reached out to Victorinox Swiss Army’s Customer Service for clarity and this is what they said… “This appears to be a decimeter used for scientific and industrial measurements. This will measure time in hundredths of a minute. This would be something used by the air force in this case.”
This is as good an explanation as any, but I was skeptical of real-world applications of such a bezel, especially when splitting a single minute into 100 increments. Hmmm, maybe there was more to this. This scale could also be used to split up an hour into 100 parts as well…essentially making it possible to read minutes and hours as percentages (per one hundred). It is much easier to make mental calculations using familiar base-10 decimal numbers. For example, 30 minutes is 50% of an hour, 45 minutes is 75% of an hour, and so forth.
The unusual decimeter chapter ring. Photo: Brian A.
I have to admit that it took me months to realize that my initial thoughts about this watch were incorrect. I just happened to listen to a Hodinkee podcast where there guest, typographer Jonathan Hoefler, was geeking-out about decimeter watches, much like this one. Mr. Hoefler said that certain professions such as pilots, scientists and bakers find it easier to use time in the decimal scale. Faster calculations are the result of working out times and formulas in your head using the familiar decimal scale.
Another version of the 9G-500 has a different logo, but the same decimeter chapter ring. Photo: eBay
I mistakenly thought that the bezel would be used in a similar way as a tachymeter scale on a chronograph. In that scenario, a user clicks a pusher and a second hand starts moving from zero. The chronograph seconds hand’s position is read against a tachymeter scale, thus converting elapsed-seconds into a miles-per-hour value. This is not the point of the decimeter scale so there is no need to have a start/stop button on this watch. The only reason to have the scale is to convert minutes and hours from base-60 to base 100 segments for faster mathematical calculations.
Technical decimeter chapter ring. Photo: eBay
What can I say? This watch did not make sense to me at first, but this kind of watch is not made for dummies like me. My thinking about it was all wrong. It would take special mind to rethink time in increments of 100 and not 60. Pilots, scientists and bakers could very well take advantage of this on-wrist calculator. I think I’ll just stick with the more familiar base-60 scale for my watches, but at least I now know that this has a legit purpose for very specific users.
