I got this little slide rule at a flea market the other day. Are you old enough to remember slide rules? Did you remember that we send men to the moon with the help of these devices? Back in the day, we had a few primitive computers but most of the calculations were done with slide rules. I wasted a few hours re familiarizing myself with its operation – the main problem is with my vision – I need a magnifying glass to read some of the numbers. I guess I will not throw away my digital calculators anytime soon! You may notice that I have placed a little electrical tape triangle pointer above 1.152 which is the conversion between knots and miles per hour, a common conversion for passenger announcements. Might be useful if I could read the tiny numbers!

I researched the origin of this particular circular slide rule and apparently it was produced in Japan by the Concise Company. Model 28N was produced for Time/Life as a give away back in the 1960′s. This particular model lacks any letter besides the number twenty eight so I am wondering about its history.

This entry was posted on Tuesday, May 5th, 2009 at 10:19 am and is filed under Aviation, General Interest. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.