Antique Mechanical Pedometer

A couple weeks ago, a friend game me an interesting an old mechanical device.  She hadn't looked at it closely, and thought it was a broken pocketwatch, but after studying it I saw it is not a watch, but a mechanical counter or meter of some kind.

It looks much like a pocketwatch, but the numbers on the dial only go to 10.  There is a big hand on the dial that looks like a watch's minute hand, and a smaller hand inside, with numbers from 0 to 100 in a circle.  The centers of the two circles are in different places.  When I took off the back, I saw a weight attached to clockwork, and something that is meant as an adjustment.  When I shake the device, it clicks and the counter (sometimes) advances one unit.

I sent emails to various people who might know what it was, including my cousin and a mechanical engineering professor here.  My cousin guessed that it was a pedometer.  Today the professor confirmed this.  He dated it to about the '30s or '40s, noting that the gears were made of stamped metal.  The workings reminded him of the cheap $1 watches of the time period, and he commented that 'pedometers are not rare.'

This was the first time I had ever heard of such a thing.  I had known that there was something of a health and fitness fad in the earlier part of the century, but I had no idea that it featured widespread use of cheaply mass-produced mechanical pedometers.

I wonder if any common thing from today will be lost in the mists of time like this.  What might we use that could only be identified by someone with a master's degree 70 years form now?