Dating post slide rules

These common operations can be time-consuming and error-prone when done on paper.

This ten-inch one-sided bamboo rule is coated with white celluloid only on the front. The back of this metal and celluloid backing contains a chart on white plastic.

Slide rules manufactured for specialized fields such as aviation or finance typically feature additional scales that aid in calculations common to those fields.

At its simplest, each number to be multiplied is represented by a length on a sliding ruler.

Many thanks to Andrew Davie and his Slide Rule Trading Post for helping to launch this little site.

This popular model, shown the to left, does multiplication and division, and not much else.

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The style of the Post logo is consistent with this date.

The instrument is marked in red at the top center of the base: FREDERICK POST CO. It is marked in black at the top right: HEMMI JAPAN.

The Post logo (in red) appears at the right side of the slide.

It came out in 1971, about a year ahead of the first TI. The famous HP-35 came out between these two, and it was a full function scientific calculator.

At the time, I would reach for a slide rule if I needed a trig value. The beauty of the log scales on a slide rule still fascinates me.