NavList:

Tony, you wrote:
"Since this type of sextant was actually used in the field (at sea) - it worked somehow. "

Maybe. Maybe not. It's an interesting issue -- the conclusion doesn't necessarily follow. Sometimes unsuccessful products are built and distributed and then found to be troublesome or barely usable in the field. Failed devices may last longer because they're put in storage and preserved. Meanwhile, every example of a successful product might be used until it falls apart. It's an interesting problem with our record of history.

What actually ends up a in museum collection? How many brand-new Zune mp3 players are in storage somewhere? Museums will have their pick in a hundred years. If the primary source evidence is ignored, the illusion may be created that Microsoft's Zune was a serious competitor to Apple's iPod instead of just a butt of jokes. So what products are in our museums today that were failures or also-rans a hundred years ago?

Frank Reed