At one point in time, the slide rule was an essential tool in a physics/math/engineering education. Built and etched with high precision, they enable a skilled user to perform all sorts of mathematical operations with speed and ease. It’s the power of logarithms in a hand-held device.
Which, if you’re the sort of person who can master a slide rule, means you can also fully grasp the particulars of how one works.
It’s a smidge harder to get there with an everyday calculator. The gulf between the solid-state electronics inside one and the button-pressing interface is enormous.
At one point in time, this beast was a handy demonstration device at the front of the lecture hall. Visible from way in the back, it lets an instructor illustrate proper slide rule use to an entire class at once.
Not that that happens much anymore, but this thing is awesome. If you found one back in the closet, you’d keep it handy, too.