Today I was re-reading "The Glass Bead Game" by Hermann Hesse (1943)
when I came across the following sentence.

"People know, or dimly feel, that if thinking is not kept pure and
keen, and if respect for the world of the mind is no longer operative,
ships and automobiles will soon cease to run right, the engineer's
slide rule and the computations of bank and stock exchanges will
forfeit validity and authority, and chaos will ensue."

There have been in this forum a number of reported "sightings" of
slide rules in books but I wonder how many of them are in literary
classics like this one.

Regards to all

Ron