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HOW do they reproduce the plants, the tree leaves and wild-flowers with such marvelous exactitude? We look at them in the museum cases in wonder. Here are the familiar fields brought to your eye just as you recall them in life—myriads of grasses, dozens of daisies; every leaf, every petal and stamen as perfect as if living. One usually dismisses conjecture with the thought that, no doubt, they picked these things in the field, and preserved or petrified them just as they were by some mysterious process.
Here is the case of the duck hawk or peregrine falcon for instance. You may recall it—a section of rock cliff nearly fills the case and sets off, as it were, the habitat of the falcon. In a cleft of the rock there is a tuft of grasses, and in the midst of it grows a fairy-like columbine in full blossom. How did they get it there?
If they picked that delicate plant and dipped it in a preservative that petrified
it just as it grew that would be wonderful indeed. But the way they actually do it is still more wonderful. Every one of those flowers; every leaf; the stalk, and its branches—is the work of man's hand!
Think of the skill, the close observation of Nature, required to do this and yet not make an obvious imitation! ■■• And yet, the basis of the process is simple enough. It is all done from life casts of the component parts. In the laboratory you will find large tables covered with boxes of various green shades of the finest thin sheet wax, rolls of fine oiled muslin de soie, and short lengths of cotton-wrapped steel wire. The simplest thing that the laboratory turns out is a leaf. Suppose that the group to be mounted requires for one of the "accessories" a branch of white oak. The first thing done is to secure representative specimens of white oak leaves of various ages, including buds. These are picked from the tree and brought into the laboratory.
The Curator's assistant takes modeling clay from a stand and makes an oblong dish of it slightly larger than the oak leaf. This he fills with wet plaster of Paris and lays the leaf face downward, stem and all, on the wet plaster. It soon hardens and the leaf is stripped off, leaving a perfect impression on the plaster.
Now, a sheet of wax is selected, matching perfectly the color of the leaf, and is pressed down into the form. One, two, or more strands of the covered wire are then laid down the midrib and veins of the leaf, and a piece of the oiled muslin placed over it and kneaded down onto the wax sheet in the form. A gentle heat is next applied, which fuses the whole together and makes the wax so plastic that it takes the impressions of every least vein and membrane of the leaf. The edges are trimmed with scissors and the axil of the stem moulded in wax to fit the form. In the case of leaves
with serrate edges the mould itself is trimmed away sharp from the edges with a small gouge, so as to give a sharp, clear outline to the wax leaf. The face side only is cast, as the oiled silk imitates the reverse of all leaves except a few requiring treatment on the under side.
The leaf is now complete, and any quantity of them can be turned out from a single mould with great rapidity. If the underside is downy or fuzzy, fine chopped camel's hair is strewed on while it is hot and sticky. If the face of the leaf is glossy, a few drops of poppy oil produce the desired effect. If dull, talcum powder, of the proper shade of color, is sprayed on.
The colored leaves of autumn require a still further process. It would of course be hopeless to reproduce the endless shadings and coloring of Nature with anything so gross and coarse as a brush, so a process was invented to match Nature's.
Assuming that a silver maple leaf, of which the prevailing autumn color is yellow, is to be made, the leaf is first cast in the proper shade of yellow wax. Then it goes to the painting room, where the delicate mottlings and colorings of the real leaf are copied with marvelous fidelity by what is known as the air brush. This instrument is essentially an atomizer, connected by hose to a reservoir into which air is pumped by a small, hand air pump.
The cup of the atomizer is filled with the color to be used, and it is blown on in a fine spray. This spray can be modified from the veriest breath of color to heavy coarse stipplings, and the wonderful colorings of Nature are reproduced by it with absolute accuracy and great speed.
The colors used are the usual artists' tubes, diluted so as to make them atomize freely. All the artist's old friends are there excepting that great mainstay, the fat tube of cremnitz white.
This cannot be used as a dilutent and general modifier because the leaf colors must be transparent or clear. The addition of white immediately turns the mixture into what is technically known as "mud.". All the lakes are barred for the reason that they are not permanent enough. Before a year passes, anything colored with a lake is several shades off the original hue. The madders are much used. Also cobalt blue, emerald green and many of the anilines.
Before leaving the subject of leaves, another question comes up. How about specimens picked on the Pacific Coast or elsewhere, when several weeks are required for shipment to the Museum? Of course, succulent plants must be cast fresh on the spot, but the majority of trees and shrub branches may be expressed east and put to soak in large
tanks in the laboratory immediately on arrival. In a few hours the warm water restores the leaves and twigs to their original freshness and casts can be taken.
The making of flowers requires more skill, but the method is the same. The flower is dissected and casts taken of the petals of both calyx and corolla. The stamens are made from fine hairs dipped in wax and the knobs formed on the end by hand. The parts are assembled, after coloring the petals, which are moulded in white wax. Such a flower as the wild rose is one of the easiest to assemble in spite of its numerous stamens. A practiced hand can finish one in about twenty minutes.
The columbine, mentioned before in connection with the duck hawk group, is one of the difficult flowers. The reader will doubtless recall it as a dark-red, fivelobed flower like a miniature king's crown, hung inverted by the center from Marshmallow Made nv Clever Hands.
a slender curved brown stalk. It looks hopeless to attempt to reproduce this delicate fairy thing with its five, incurving, red tines, each capped with a yellow knob. If cast entire in a waxen bullet it would be horrible, leaden. To make it, each lobe, which is virtually a petal tightly curled, is opened out flat, and a cast taken of it. A thin white wax sheet is now worked into the mould and cut a sixteenth of an inch larger than size along one edge. A steel rod is*prepared by pointing it to exactly fit inside one of the tines and the wax petal is then curved around it as a form. The extra sixteenth-inch laps over and is burnished down with a smooth, warmed rod. The little knob at the end is worked up with the fingers. The five lobes are colored with the air brush, the stamens put in and the flower assembled complete around the stem. In most of the flowers there are so many colors that white wax is usually selected as the color to form the parts with.
All the grasses, including the canes, are simple and easy to mount. Most of them arc simply dried and then re-colored with the air brush. If the leaf is broad, like the cat-tail, it is cast and made up from wax sheets. In large stemmed fleshy plants like the sagittaria water lilies—the ones with the flowers in a close blue spike and spear-head leaves—the stems are cast from life and molten wax
poured around a stout steel wire. The leaf is made separately as described before and secured to the stem.
The preparation of tree and plant fruits presents a range of problems, varying in difficulty from the easily reproduced fruit of the pawpaw, to the well-nigh impossible catkin of the white willow. The laboratory is still wrestling with this latter, after many flat failures.
Beginning with the large, smooth fruit of the pawpaw—with which may also be classed the persimmon and wild plum— the first step is to beat out a flat ribbon of clay about an inch wide and mould it edgewise around the fruit, resembling the rings of Saturn. Thick plaster of Paris is poured over the fruit, the ring acting as a stop, and followed up with a paste of the plaster, moulding it with the hand as it sets. The clay is then peeled off, and any fins of plaster that may have crept up under it are trimmed with a sharp knife.
This same process is repeated by dividing the remaining half of the fruit into two sections and plaster-moulding them one at a time, the final result being a three-piece mould around the fruit. It is then drilled at one end and poured full of wax, giving a cast of the pawpaw, which is forthwith colored to life with the air brush.
Any fruit treated this way must be first coated with beeswax thinned out in kerosene. While not thick enough to fill any detail, it still is greasy enough to part the plaster from the fruit.
A second method of preparing tree fruits is to actually preserve them by saturating with glycerine on the osmotic principle. Acorns, winged ash and maple seeds, and the tiny green flowerets that
are the blossoms of so many trees, are all treated in this way. Glycerine has a very strong affinity for water, though it must be first diluted with it to enter any vegetable tissue. Besides this, the solution must be an insecticide and germproof, so formaldehyde and arsenate are added. The acorn or maple seed is soaked in a bath of this solution. Gradually the fluid enters the pulpy interior, forcing the water from the cells, entirely replacing it with non-shrinkable, deliquescent glycerine. The seed will not hold its color, turning brown in a few months, so the air brush is used to color it to match a green fruit.
Still another method, applicable to hard dry seeds like the chestnut and sweet-gum burrs, is to dry them out and recolor with the air brush. Many of the berries, such as the red sumach drupes, are also treated this way.
Hardest of all are the catkins. Being full of interstices, it is impossible to cast them in wax, they are too perishable for the glycerine process, and, unless accommodating enough to dry in shape like the catkins of the birch family, the last resort is usually to make them laboriously by hand. And if, in addition to countless tiny berries, the catkin further adorns itself with fine downy fuzz, colored both black and white, the ingenuity of the curator is well-nigh overtaxed to reproduce Nature's handiwork.
To prevent branches and twigs from shriveling, there are large vats of glycerine and formaldehyde solution in the laboratory, in which they are put to soak. Heavy branches, and tree trunks with smooth sappy bark, are simply painted with the same solution, as it is only
necessary to impregnate through the sap wood.
The preparation of such a panorama as that of the bird life of the Arizona deserts, for instance, involves an immense deal of close Nature observation, study by life photographs, and skill in mounting the birds and plants'. The expedition sent out for this group consisted of two curators, a museum artist, and some helpers hired on the spot. Camp was pitched near the Carnegie Laboratory, a short distance from Tucson, and the work begun of collecting specimens and photographing the birds in all conceivable postures of life action. The cameras were concealed in blinds near nests, and thus characteristic postures were photographed from which the birds would later be mounted. The scientists then selected the most typical scene for the proposed group, and decided what must be included and what left out. A strip of ground on which might be several desirable bushes holding nests, was marked off and photographed from different positions. Then every stick and stone in the strip was gathered up and color-sketches of all objects made on the spot. If a characteristic bush or cactus grew just outside the strip, but no good specimen on it, it was taken in place of non-essential plants. When the group was finally complete, every last foot of it was packed up in sections and expressed in boxes to the Museum—■