The true northerner. [volume] (Paw Paw, Mich.) 1855-1920, 1884-11-06
A HAIRS THICKNESS.



A Delicate Machine I'm tho Postofice De-
partment and Its Use.
A curious little machine in the Office
of the chief of the stamp bureau of
the Postoflice Department is the cause
of the cancellation of the contract of
the New England firm with the Govern
ment for furnishing envelopes to the
Postofiice Department. 1t IS a queer
looking contrivance-a cross between
set of butchers scales and ordinary
grocer's scales, or, rather, a combina-
ton of the two. There is larger dial,
like the face of clock, with the little
hand that flies around the face pointing
to the figures at the side, which are ar
ranged like the figures on the clock
face. with little dots between. You
see three dots? ?" said the gentleman in
charge, inquiringly. well, the space
thousandth of an inch. Getting it
down pretty fine, isn't it? You see
this movable piece Of iron here, which
comes down with smooth surface upon
this other solid surface? Well, the
raising or lowering of that moves the
pointer which runs round the dial. To
test the thickness of sheet OF paper,
we simply place it between this movable
piece and the solid surface below, and
when the movable piece of iron comes
down upon the paper, the hand regis
tiers the true thickness of the paper.
Delicate instrument? Well, should
think so. just give me hair from
your head. will you?"
Then he took q hair and slipped it
deity between the movable pieces.
The hand on the dial followed the mo-
tions of the screw until it stopped at
the figures 20 Just 20 16-10OOths of
an inch IN diameter" he said. "Now
let me try hair from your mustache.
They are generally much larger, es-
pecially if you have been in the habit
of shaving" He took up pair of scis-
sors and clipped off a hair from the
mustache and placed it in position.
The hand stopped at so. Fifty L.
l000ths of an inch thick" he said.
"That shows the effect of shaving. I
measured hair from the hand of a
gentleman a few minutes ago which
was 10 16-1000ths thick, but those in
his mustache were precisely the same
thickness, the reason being that he had
never shaved. Yes, that is the ma
chine that proved that the firm making
our envelopes was not fulfilling its con-
tract" he said, as he fell back admir-
ingly.
"By this dial we can see just the
thickness. By this lever, which is very
much like pair of grocer's scales, we
can tell just what pressure the paper
will stand. You see, we have two
other movable pieces of iron here,
with a hole entirely through both, and
a plunger which passes through that
hole. Well, we put the paper between
those pieces, which, when they are
pressed together by this lever, hold il
firmly. The plunger, which passes
through the opening in the two pieces
of iron, encounters this paper thus
firmly held. To know what the pres
sure is, we have the plunger attached
to scale lever with weight attached
like an ordinary pair of scales, and, by
moving this weight out along the lever
until the paper breaks, of course We
can see just what the weight is that
made it break. See! Very simple after
YOU understand it. Well, that Is what
the paper-makers thought after they
had lost an $50, 900 contract by it. II
was new thing to them, but they &C
knowledged that they were beaten
when they saw it.
This delicate instrument, only re-
Gently invented, is a companion piece
to the scales in the Assayer's Office o.
the Treasury, by which the weight of 6
| bo;r is accuratelv tested -ynSLiuOtOI
Post.