The Quest for the Holy Grail of Slide Rules

I will now tell an interesting story about something I uncovered.

In about 1997, I was sitting and working at my computer and an email popped into my mailbox.  Someone wanted to know if I wanted to buy a slide rule. I didn't recognize the name, but I answered anyway.  Okay I'll bite, "What kind of slide rule do you have? And, oh, by the way, where did you get my name or email address?"  Most slide rules that come up are fairly boring.

A little while later a reply came with more information. "It is a Thatcher and I saw your name on some website advertising that you want to buy slide rules."  "Interesting, a Thatcher." I thought. "I don't remember ever putting an ad anywhere for buying slide rules.  I wonder where she saw that"

There were two principal models of the Thatcher that were made. Production started in 1881. There is the 4012 model and the 4013 model.  Both are almost identical, except for one thing.  They both are almost two feet wide, they are built around a 4 inch diameter cylinder with rotating vanes around the cylinder.  The theory behind a cylindrical slide rule is that by wrapping the scales in a helical fashion around the cylinder the scale can be made considerably longer.  The longer the scale, the more accurate the computations. The principal difference between the two Thatcher models is that the 4013 has a bar across the front of the device to which is attached a magnifying glass that can be adjusted to "read" the answer to a computation.  This allowed the device to be very precise -- so much so, that it was the most accurate device available for many years.  And to get the most out of the accuracy, you really do need a magnifying glass to "read" it.  It turns out that the 4013, while more expensive than its brother 4012, had many fewer produced, and consequently, they are extremely hard to find in good condition -- and they are so very expensive.

Now, back to the story, I assumed it would be a 4012 and probably, like most, fairly deteriorated.  The response I got said it was a 4012 and after a few more back and forths, I concluded it was worth seeing.  It turned out, of all places in the world that it could be, it was about an hour away, in Springfield, MA.  I hopped in the car, went to the bank to get the required cash, and off I went to Springfield from Connecticut.

I arrived at a small house in an older section of town. I knocked at the door and this woman came and let me in.  She showed me to the table where she had on display, unbeknownst to me, two Thatchers.  One was a 4012, and... the other ---the other  was the Holy Grail -- a model 4013.  I tried to restrain myself from showing how elated I was.

The story took a very strange turn.  She was apologizing to me that she had me come all that way, but she had already sold the 4012 Thatcher that I had come to buy........ But, if I was interested, she had this other one almost the same over here.  I knew it, it was a bait and switch!

I looked it over, it was beautiful. It was well preserved, and it had all its parts. "I'll let you have this one for the same price" she said.  "I'll take it"

So, that's how I got the Thatcher and now it sits right next to the Curta in the display case in my living room. But that was not always the case.  I had not purchased the Curta at that time. I was still on the trail to find one.... and that is the next interesting adventure.