THE SHADE OF J. BALLANTINE HANNAY 233
work
they were doing on the kind of tools I had already seen in the museum.
In one room a man was carefully plotting a diagram on a yard-square
piece of paper. There were lines converging to the center of two
concentric circles, and an irregular pattern of marks was spotted here
and there around these lines. "This represents a drill crown," he
explained. "I'm trying to work out the most effective places at which
the diamonds should be set on it, so as to get the maximum result when
it's grinding. We figure out from the wear and tear already visible on
a used crown where they get the hardest treatment, and we try to set
our diamonds with this knowledge in mind. Over on this table, as you
see, we're resetting used diamonds. As one point wears down, the
crystal can be turned so that a fresh point sticks out; that way, one
diamond lasts a long time."
We
moved on to another room where in the presence of three or four men in
work aprons a number of diamond-pointed drills and needles were being
tested on rotating disks. There were disks themselves being tested as
well, solemnly turning at set speeds, round and round and round for a
set number of hours, with careful microscopic examination at intervals.
In this room, too, diamonds were being ground down to the various
shapes needed for cutting special tools, on wheels that were saturated
at their rims with oil and diamond dust. All this sounds as if it were
happening in a factory or workshop, but in reality the impression given
by the big clean rooms was more that of an artist's studio, even where
glass cutting was being studied and an occasional glass plate was
deliberately broken for the sake of testing.
When we came at length to the special laboratories devoted to Dr. Custers' studies, in the physical section, it was different.
