Someone at work brought some old engineering tools today. It was pretty cool since many of these are now relics in light of CAD and computers.
This is a set of compasses used for drafting. Drafting tables used to be a common sight at engineering companies. They have pretty much been eliminated by the use of CAD.
The first slide rule was developed in the 17th Century by the Reverend William Oughtred based on the work on logarithms by John Napier. Prior to the invention of the calculator, this would have been used to help with multiplication and division. Depending on the model, you could also use it for roots, logarithms and trigonometry. I never had to use one but I used to have one that I would play with. I would imagine if I played with one again, I'd pick it up.
Green bar paper was a pretty common sight to computer users back in the day. We used to use this kind of paper in Goddard Lab as I was studying computers at Eastern Michigan. This would typically come off a huge printer and has largely been replaced by Laserjets and Inkjets.
The Hewlett-Packard 45 was a development of the HP-35 and was introduced in 1973. It was noteworthy as the first calculator to introduce a shift key which enabled more functions. It also used a format called RPN where you would enter the numbers and then perform the operation. For instance, if you wanted to add, you would enter the first number and then the second number and hit the plus sign. This took some getting used to but once you did, it made more sense. I never had one of these early HP calculators but I did have an early Texas Instruments calculator that looked similar. I did end up getting an HP graphing calculator and learned RPN. It was tough going back to other calculators after that.