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- 24 • photography or photostat of each map finally completed for publicationo These re­ produotions are made on the same scale 1:24,000 to simplify the matohing of Unfin­ ished adjoining sheets. These reproduotions in negative form make it practioa1 to supply the demands for oopies of the map pending the final pUblioation of the map. -000- THE REPRODUCTION OF MAPS DRAWN ON ACETATE SHEETS by C. H. Birdseye Chief, Division of EngraVing &Printing. U.S.~.S. Other papers on this Program have described the compilation of maps on acetate sheets and the writer will outline Just enough of this compilation to indioate the type of drawings ti~t are presented for reproduotion, so that this paper will be oom­ plete in itself. The proJeot is oonduoted in oooperation between the Tennessee Valley Authority and the U. S. Geological Survey. It consists of a oomplete series of planimetric maps of the entire area of the Tennessee River Basin in about 750 seven and one half minnte quadrangles on the scale of 2000 feet 'to the inoh (lI24,OOO).~ Each of these maps is given a serial number of the fifteen minute area t.ogether w1t.h 'the proper­ quarter and also a name selected from an appropriate town or featu%'e on the map, suoh as Johnson City, 19B-SE Tenn.-N.Car. rhese sheets are oompiled in Ohattanooga on sheets of cellulose aoetate. At the beginning of the proJeot, three sheets of oopy were presented, as follows; (1) culture and lettering in blaok, for reproduc­ tion in b1aok. (2) Drainage in black for reproduction in blue. (3) Woodland areas in yellow or green for reproduction in green. Before the sheets are sent to Washing­ ton for reproduotion, ozalid prints are made in Chattanooga for the preliminary use of the Tennessee Valley Authority. This procedure requires that all of the copy, in­ cluding the lettering, be drawn on transparent media. All of the names ar~ set in type and printed in black on Japan tissue by what is known as the !'loat Lettering Prooess invented and patented by Colin Landin. These sheets of tissue are coated on the baok With a solution of adhesive made from glyoerine, gelatin, sugar and water, a.nd the separate names are cut from the tissue sheets a.nd "floated" in place by rubbing each name With a fine brush dipped in water. At first, the lettering was placed on the oulture sheet but some difficulty was experienced in making the names stick to the cellulose sheets and some of them be- came detached by handling during the reproduotion processes. Ea.rly in the program, -'---J therefore, the lettering was placed on a specially prepared ozalid print of non­ photographic blue. This procedure had two objections, first that the ozalid prints presented to the Tennessee Valley Authority had to be lettered by hand and seoond, that we had to use a different camera in Washington because of the opaque background. The first of these difficulties has been eliminated by II floating" the names on a sheet of transparent traoing paper mounted on oe1lu10se aoetate to register the base projection. At first, the ~ulture and drainage were inked on separate sheets of cellulose. Some diffioulty in register was experienced and soon after the project was started. the oulture and drainage data were combined on one sheet of cellulose~ Later, the woodland copy was submitted i~ black whioh has a more even body and better photo­ graphio properties trAn either yellow or green. At the present time, three sheets of copy are presented for each quadrangle, as fo110ws: (1) 'Julture and drainage drawn on cellulose acetate in black for reproduction in black and blue respectively; (2) woodland sprayed on cellulose aoetate in black for reproduction in green; and (~1 lettering stuck on a sheet of thin tracing paper mounted on cellulose acetate. At the beginning of the proJeot a ·stiok-up projection" W8,B drawn on a metal mounted sheet of drawing paper for a eheet in each row of quadrangles (25) to cover the basin. This Was done for two purposes, first beoause there Was some doubt. that the different oolor plates would register well enough for combined color printing and second, beoause the ·stiok-up· saved the photographers time in bringing the - 25 - different drawings to a perfeot 80ale without setting beam oompasses to measurements taken from proJeotion tables. No effort was made to draw these proJeotions on ground ground glass which would have saved the photograph.ers a little more time but would not have been available for the transferrer. Because of a series of circumstances, it was deoided to print these maps on a direot, rather than on offset press. This deoision was influenced largely by the faot that the edition is relatively small, that a few oopies are printed on traoing oloth and traoing paper, and that we oould use either a straight or a prism camera. in the photography. Photography. All of the photography is accomplished by the wet plate prooess. these plates are made by using seleoted plate glass of size 24 x ~O inohes. The first operation is to flow evenly over the plate a solution of albumen used to hold the other solutions on the plate; when dried, the plate is coated With collodion, an organio base composed of ether, aicohol, guncotton and iodide; the plate is then lowered on a rack into a stone or enamel bath containing a silver solution. The plate is fully sensitized after it has remained in the silver bath about 5 minutes, and it is plaoed, in the negative holder of the camera which extends into the dark room. Using the 50 x 50 inoh direot oamera with a lens of 45 inch fooal length, the oellulose acetate sheet of the oulture and· drainage base is placed on the copy board under plate glass, the transparent sheet being reversed over a sheet or white paper so that the negative is made by exposing the drawing through the cellulose sheet. The ·oamera is focused for sharp defin1tion at the proper scale, using the ground glass focusing plate in the fooal plane of the oamera, and a pair of beam compasses set to proper lengths from the ·stick-Up· proJeotion. The sensitized plate is then substituted for the focusing plate and the oopy is illuminated by two arc lights placed in front, but slightly to each side, of the copy board. The proper exposure 1s tlmed accurately, usually from two to four minutes. After exposure, the photo­ grapher, still working under a safe light in the dark room, develops the plate by using a solution ot sulphate of iron and acetic acid, and washes the plate with olear water. The photographer repeats the process With the same setting of the copy board and oamera 80 that he makes two duplicate plates ot the culture and drainage, for use by the negative cutter. The photographer then photographs the woodland copy in the same manner, revers­ ing the draw1ng and expos1ng it through the oellulose sheet. All three of these negatives thus beoome direot plates suitable for processing to a reversed print1ng plate and printing in a direct press, Just as though the negatives were made by a prism oamera. Inasmuoh as most of the lettering sheets used thus far have an opaque baokground, and the new lettering sheets on thin traoing paper mounted on cellulose acetate are not transparent enough to photograph sharply through both cellulose and tracing paper, we use a prism oamera with a 42 inoh focal length lens and do not reverse the lettering draWing. In all other respects the operations are the same as With the direot camera. After the plates are developed 1nthe dark room, they are taken into the outer laboratory and subjected to several operations. They are first cleared up by an ap-. pl1cation of oyanide of potass1um flowed over the plate, whloh removes all silver not affected by light. The plates are Washed thoroughly and placed in a rocker bath oontaining a oopper sulphate solution. After washing again the plates are placed in another rocker bath containing a nitrate of sllver solution, whic.h tends to bring out the desired blaok and White baokground. These two rocker bath operations are usual­ ly repeated With thorough washing of the plate between each operation, so as to give the proper density to the plate. The plates are then ooated With a gum-arabiC solu­ tion to proteot the surtace. Allor the above operations after the plate is brought from the dark room result in a properly fixed and intensified negative. Negative Cutting. On one of the duplicate plates showing both oulture and drainage, the neaat1ve outter paints out, by means of a brush and asphaltum, every­ th1ng except the oulture and the projection lines whioh are to be printed in black, - 26 - restores with a fine engraving tool or ne~dle any lines whioh have been damaged by painting out the drainage, and retouohes the negative to remove any spots or other blem1shes. On the other duplioate plate he paints out everything esoept the drainage and retouohes the negative in the .ame manner. Usually, all that the negative outter has to do with the woodland and lettering plates is to restore any lines that are not sharp enough to print and to retouoh the negatives to remove any blemishes that would print.' Sometimes, however, either the woodland or lettering plate requires oonsider­ able Iglass engravingl (outting through the film but not into the glass) by means of a fine engraving tool or needle.

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