The Daily Ardmoreite. [volume] (Ardmore, Okla.) 1893-current, 1918-02-16

scale, and changes are constantly beine |
made in guns and projectiles, airplane
engines and motor truck parts. for ex.
ample, so that new gauges appear week
ly at the laboratory for painstaking eX-
animation. registration, numbering and
inscription with the IN. L. L." that
means passed.
The use of yard sticks and brass rules
are unknown, apparently, or thorough
ly mistrusted at the laboratory | did
not see one in the many subsidiary de.
partments / visited For one thing a
yard or meter stick would be of no pos
sible use in measuring fractional inch
amounts Most delicate apparatus had
to be designed and built at the lapora
tory, simple enough to be used by girl
observers who have had no scientific
training, and sufficiently durable as to
be proof against clumsy fingers.
In these new neurology devices the
laboratory has been ahead of the world
in the adoption of rays of lights as in
dicators when measuring the most
minute gauges. For instance, when
screw gauge the length of a thumb nail
is being checked up, and il is required
that the distance across, depth and
angle of each almost imperceptible
thread should be measured the ordinary
method would be 70 have a dial and
carefully balanced indicator.hnger to
record the periods when a sounding
needle should plumb the bottom anc
sides of the microscopic walls of the
screw threads But the indicator finger
| has a certain amount of inertia, it has
a tendency to lag, which, though af.
fecting a reading insignihcantly, would
| be enough to give a clean bin of health
to a screw lacking vital perfection in
some detail.
Therefore, a projection machine IS
used to throw beam of light on a mir.
ror as the sounding needle moves; the
| light is passed from mirrors on ceiling
and walls until finally it is reflected onto
a ruled sheet in front of the girl ob
server, who yawns slightly and makes
figures on sheet This may SCUM
complicated or of experimental fraei,ty
but when | tell you that at one proiec.
ton machine girl observer will pass
or reject 12O screw gauges day, with.
out a shadow Of error and tha. this
has been going on daily for months and
months, you will realize how marvellous
ly practical 1t is.
Minute Measurement.
Now that | have you believing that
this projection measurement Is very
commonplace, humdrum affair as all
world wonders become when tucy are
beleved-let me tell YOU what l., accu
rately measured in the threads Of 4
screw of the stature Of baby ant
Seven dimensions of each thread of each
screw have to be surveyed and chartcd
the dimensions being
Outside diameter of thread.
Core diameter.
Effective diameter.
Crest radius.
Root radius.
Pitch.
Angle of thread.
The work is positively -lirl sque. It
had a fascination for me that threat
ened to upset Mr.. Brookes' plans for
escorting me through other depart
ments Whoever thought that we could
deal so exactly in values that would be
]
scopic minutaeia is Of consequence in
the business Of carrying out a grown
up worlds decision that there shall be
fewer of better Germans! But more
than this, they placed one of the screws
on the lens Of another projecting ma.
chine, and 10, before me was a noun
tain range a foot high shining on a
sheet on which was plotted, for com
parison the drawing Of the magnined
range of screw threads as specified by
the war Office or admiralty. one of the
shadow mountains had a big boulder
cllnging to its side. Dust" said MIR.
Brookcs, and the boulder was pufed on.
There are several varieties of these
projection measurement machines, two
that require theatte cts where a stere.
upticon lantern flashes the mountains
on an adjustable screen, but not only
screws are checked with patterns in
this way but cylinder gauges as well
/ found several hours later that this
uniuue method of Misunderstanding was
used in other departments where most
delicate balancing is done; and in this
case the faint beam Of light is actually
reflected through a jar of distilled
water containing a cake Of alum so that
the trhe of heat in the ray should be
extracted and not affect the scales!
The method of measurement Of ring
or circular gauges is different. Cylln
ders Of known diameter are placed with
in the ring, and the gap between them
filed with Johannson gauges which are
little special steel rectangles OF the
area of a safety razor blade, but con
, sideraby thicker. Their surfaces are
so wonderfully smooth that they cling
together from surface attraction, not
, magnetic, and they have to be rubbed
; apart to separate them. Different sizes
OF these shiny rectangles are placed in
: the gap until an exact fit is fOunG
, until the next thickest lozengo will no
fit. Then the units are added for a tota
that is the measurement OF ring diam
I eter.. These Johannsen gauges. made
in Sweden by a secret process, are cor
rect to within one hundred-thouSandtr
of an inch in thickness and paralelism
D They have to be picked up with In
sulated twee2ers so that hand hea
. will not expand them.
Other Tests.
r Later in the afternoon l saw testint
, Of barometers, official time pieces