I was visiting a friend around 1975-76 who had taken a job with
Honeywell's Government Systems Division in Phoenix shortly after
Honeywell took over the GE Computer operation there (there were still
GE mainframes to be seen here and there).
At any rate, the system under development that I saw used water-
against copper-membrane cooling. It was composed of several racks
connected by cables and what looked to be vinyl tubing. The whole
affair was located in a big square housing about 8' on a side. It
literally was a "walk-in" affair. There looked to be enough room in
there for a small table and a couple of chairs. A very sexy
operator's console with nixie bar-graph displays among other things.
I don't recall what system it was. But you could definitely hide a
few people in it.
--Chuck