only slightly OT- how common were these promotional specialty slide rules

This was probably aimed at people who did purchasing of the hydraulic cylinders and supplies, to free them from having to ask the engineers to do all the calculations when they have questions. These would have been people who knew how to use a sliderule, but who did not carry the various formulae and constants around in their heads, so the GAL and DIA scales helped them come up with quick answers.

Enjoy, DoN.

actually, that wasn't intentional - if anyone asks if they can pay by another (legit) method, I always say "fine, no problem" - I hadn't noticed anything, but not that you point it out, I'll look - it think what happened is that they just took away the other options. --- I just checked, and that is in fact what they did - there is no option for "money order" or "check" or "cash", only paypal, propay (whatever that is) and merchant credit cards.

Have you seen any of these things before? You may be right, but all I'd seen before was the paper/cardboard items.

I was an electro-optical guy. One of the gadgets we all sought were the GE "black body" slide rules. You called a GE industrial rep and asked for one. They had a number of very complex functions, which in some cases were transcendental equations, very hard to work even with a slide rule or set of tables.

It was formally called the Radiation Calculator, courtesy of the Aerospace Electronics Department.

For instance, you could pick two IR wavelengths, and a temperature, and calculate the power emitted from a surface. It would do units conversion, find the wavelength of peak emission for a given temp, and a few other goodies. It also had printed on it a number of constants used in physics computations.

In the days before desktop computers it was certainly a big aid.

After wasting months trying to recover money from lost money orders (buying) and having people tell me the check is in the mail (selling) etc... YES. The only exception when I sell is if the person picks the item up and hands me cash. Paypal sucks when it comes to dispute resolution, but they do a good job of transferring money.

I believe they were pretty common, especially in engineering-ish industries. I've got several of them, some from clients of my dad's (he was a business consultant) and some from other sources. I expect it was the 1960s equivalent of the modern too-small-to-be-useful USB stick with a corporate logo on it.

Most all pilots still learn how to use an E6B:

Most all pilots still learn how to use an E6B:

Probably also the case with Celestial Navigation. Likely some were sight reduction tables that would get one within a few dozen miles if caught in a lifeboat with only a sextent. I have not seen such a device, though. I do have some good books on Celestial dating from a

Bob Swinney

Bob Swinney

O.K. I think "ProPay" is an alternative service like PayPal, so they can claim that they aren't shutting out *all* other ways other than their own PayPal.

I've owned and used cheap printed on wood slide rules, but not custom ones like this -- just the cardboard ones -- some of which are nomograms/nomographs, and others real (if limited functionality) slide rules.

Enjoy, DoN.