Mathematical Instruments

 PBS recently aired a show about the Apollo 11 mission.  It reminded me of all the thrill, wonder and angst I had back then watching astronauts walk on the moon's surface.  The show included glimpses of engineers carrying slide rules.  NASA had computers for repetitive tasks but in the 60's the slide rules were still in use for a quick-backup sanity check or calculation.  There are old pictures of people using slide rules for many activities - rocketry, hydroelectric power, cars, WWII bombardiers, chemical research, Trinity nuclear test, etc.    A slide rule was still a necessary tool while I studied physics in college in the early 70's.  Hand-held calculators had just become available but were wildly expensive.  Slide rules, n the hands of someone who knew how to use it, could do arithmetic calculations practically as quick.  Unfortunately they were in high demand among students in the sciences and  easily stolen. We all had backups or carried them in holsters from our jean belts.   In the late 70's when I was training for my private pilot's license, I used a special navigational slide rule.  By that time, personal calculators were finally coming down in price so I also bought a Texas Instrument TI-30 and a specialized calculator with flying functions built in.  Eventually all of my slide rules and early calculators were packed away (couldn't bring myself to toss them).    Brother Brent gave me an Addometer his father-in-law had from the '40's.  It used dials to add/subtract/ etc. and was marketed for small businesses.  It seemed wrong that these instruments were stuck away in boxes when they had such a story behind them.   I gathered them all  together and asked the brothers if they could make a display for them that I could mount on the wall yet be able to take them out and still use them.  Brother Phil worked to get it done just before he left.  Geeky, I suppose, but way interesting and so unique I'd say no one else in the area has one like it.