My 8 year old daughter and I are watching "Full Court Miracle", one of
those made for TV kids shows. I just watched a scene in which an old
algebra teacher takes out a slide rule to calculate the flow rate in a
gasoline powered generator. There's a glass pipe on the outside of the
generator that is partially filled with gas, and a ball float on top
to indicate the amount of gas left. Before he calculates, he uses the
slide rule to measure the level of gasoline in the pipe by placing the
slide rule next to the pipe carefully and seeing where the ball is
next to (on the D scale, presumably). After he's used the slide rule
to measure, he then moves the cursor around to get the answer.

From the look of it, it was a Versalog.

Bev