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levers of the switchtrack mentioned
above, and this, in turn, is controlled by
the 256 keys of the man-operated typewriter
key-board.
Below the belt is a double set of
pigeonholes. Each pigeonhole is so set
that one of the metal receptacles passing
above it, as it travels over a drum at the
end of the machine along the belt, can
open out over it, and drop the contained
letter in. But each of the various
pigeonholes corresponds to only one of
the 256 combinations of positions which
the rods on the metal receptacles can
assume.
The operator sits in front of the keyboard.
The letters are stacked before
him automatically. He reads the address
on the front envelppe. depresses the
corresponding key, and this key shoots
the letter from the front of the stack on
to a moving vane which fans the letter
POSTAL SORTING MACHINE 557
into the side opening of one of the metal
receptacles. At the same time the depression
of the key has set the switchtrack.
This shifts the rods on the bottom
of the receptacle to the proper position,
so that it will open out and drop
the contained letter into the proper
pigeonhole beneath. Shooting away the
top letter, of course, exposes the next
letter, and so forth, until all are taken
care of. An employe runs a separate
jogging and facing machine which keeps
constant the supply of letters.
A separate machine arranges the letters to be sorted, and they are held in place before the operator by means of a spring.
There are two big advantages of this
method over the old. In the first place,
it is mechanically much faster than the
hand-distribution of letters. In the second
place, with 256 primary separations
instead of 28, it is possible to eliminate
at least sixty per cent of the rehandling
and redistribution which letters now
receive.