Though I cannot say what type, the circular slide rule was most likely a "flight computer" which pilots use to plot course on the back, on a grid, to account for wind effects.

Charles
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On Sun, 5/1/16, 'Eriugena' eriugena@... [sliderule] <sliderule@yahoogroups.com> wrote:

Subject: Double SR Sighting
To: sliderule@yahoogroups.com
Date: Sunday, May 1, 2016, 7:25 PM























Hi all,  I was trying out local TV via
antenna and came across an episode of the Outer
Limits where William Shatner stars as an astronaut who
comes away from Venus craving heat. Coincidentally, the
Venus mission was called Project Vulcan.  At about 15 minutes into the
broadcast (commercials included) Shatner, now promoted to
general, was at home making calculations with a slide rule.
His wife then picked up a large circular slide rule and did
some additional calculations. It looked like a large Gilson
on the front but had a grid on the back. I don’t know
if this was a real slide rule or TV Hollywood’s
attempt to make something look futuristic. The episode is
called Cold Hands, Warm Heart.  It’s nice to have a
two-fer where slide rules are concerned. Also very nice to
see a husband and wife collaborating in science.    --David