The Princeton union. [volume] (Princeton, Minn.) 1876-1976, 1893-12-14
DRAWINGS IN MULTIPLE
what Is Done at Funny Little Build
Ing Back of the Traaannu


Ing Back of tho TREASURY.
The effect to the eye was somewhat
Ike tnat OF arranging scenery on the
stage Approaching from the direc-
tlon OF the Washington monument it
was dlfhcult to make out what sort
OF performance was being conducted
on the high platform attached to tn q
small frame building in the rear of
the treasury department.. Persons
were wheeling about q number of
eueer-lookipg frames OF large size.
Each one was placed in such a way
that the bright suns rays wore re-
hected from its bright surface daz-
zllngly toward the beholder, says the
Washington Star.
PROBABLY there are comparatively
few people in Washington who have
taken notice of this building or who
have any notion as to what sort of
work is done there. On entering
the door one finds himself confronted
by a spectacle of many great tanks
apparently full of chemicals. On
the surface of these tanks big pieces
OF paper are floating and at intervals
busy workmen take out the wet
sheets and put in others, hanging
the former up to dry. On the paper
are all sorts of architectural draw
ings and designs.
One is directed up stairs to the
superintendent in charge, Mr.. Mac
Blair, who explains that the estab-
llshment Is branch of tho Office of
the supervising architect OF the
treasury. Here the plans for Uncle
Sans public buildings are multi
piled by the aid of photography
One reason why much of such work
has to be done 1s that numerous con-
tract bidders for in the way of con-
struction must be supplied with
copies of the drawings, on which
they have to base their estimates as
to cost, etc. OF course, to reproduce
the drawings by hand would be enor-
mously laborious and expensive; but
the sun does it comparatively cheap
~ and with absolute accuracy. The
only disadvantage of the celestial
workman-not intending to refer to
him as a Chinaman, be it understood
is that he frequently goes on a
strike. sulking behind q cloud.
Architects all over the world
utilize the suns rays for the purpose
OF multiplying their drawings. They
take plan or elevation, for example,
and reproduce it in the shape of what
is called ''blue print" That is to
say, they lay tracing of it upon a
sheet of sensitized paper and expose
them to tho solar orb. Wherever
the sens itized paper is not protected
by the lines Of black ink on the
tracings it turns blue and the result
is sheet with a blue background,
on which all the lines of the tracings
are copied in white. In other words,
it is a negative.
But the method practiced at the
government establishment described
is much better. A chemically pre-
pared paper is exposed to the sun
beneath an ink-drawing or tracing
linen, just as in the case of the blue
print. But the result Is that the
lines appear In light green on white
background. Then the sheet is put
into an acid bath. which turns the
green lines to black. Thus a posi-
tive is obtained from a positive,
which is much more satisfactory. 1t
is in this work that tho frames
already spoken of are used, and on
any fine day they may be seen out
On the high platform at the rear of
the building, with their glass covered
faces toward the sun.