Sliderules

Looking at slide rules on Ebay, I notice a LOT of sellers post pictures of slide rules with their slides flipped. The slides might be flipped end-for-end, or rotated 180°, so the right scales are showing, but upside down.

I see it often enough that I think it MUST be on purpose, but I haven't figured out what that purpose is.

I realize that some rules are designed to be used with the slide flipped, like Mannheim or Rietz rules with trig scales on the back of the slide.

And I realize you can flip the slide end-for-end to use the C scale as a CI scale.

But recently I saw a Pickett USAF Aerial Slide Rule for sale on Ebay, and its slide was flipped so that the C, S, T, CIF, CF scales were on the side of the rule with the ALTITUDE and GROUND SIZE scales. I can't think of a way to use that rule that way!

For the attached picture, I flipped the slide on my own Pickett Model 520, just to illustrate. I have to say, it felt SO WRONG doing that!

Anyhow, all of this is just to ask, why do they do this? Is it ignorance? Do they have NO idea what a slide rule is and how to use it? Is it on purpose? Is it a trick to get us to pay attention? Is it supposed to make potential buyers think, "Oh, no! I must RESCUE that slide rule from that heathen!"

What do you think?

#sliderules