( http://www.artmuseums.harvard.edu/sargentatharvard/drawingglossary.html)

Escrito por Edward Saywell, Lynn and Philip A. Straus Drawing Intern, 1996-97. Los ejemplos en paréntesis son obras del Departamento de Dibujo de los Museos de Arte de la Universidad de Harvard.

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Album: Typical storage format of print and drawing collections until the nineteenth century. Drawings, whether by the same artist or not, were mounted onto pages of a blank bound book. Among the finest surviving examples are the Spencer Albums of old master prints in the Print Department of the Harvard University Art Museums. (Circle of San Gallo, album with forty-three architectural drawings, 1932.271; Achille Leclère, album containing seventy-seven drawings, 1965.21).

Auxiliary cartoon: See cartoon.

Bistre ink: A brown ink made by boiling or soaking wood soot in water. Once the liquid is filtered to remove any insoluble residues, the end result is a transparent and luminous ink. The exact tone of the ink depends upon the kind of wood that was burned to create the soot. Chestnut, for example, results in a golden brown ink, while birch produces an ink that is yellowish brown. It is often indistinguishable from faded iron-gall ink. (Giovanni Battista Tiepolo, Doubting Thomas, 1961.173).

Black chalk: A composite of carbon and clay, black chalk has a natural cohesiveness that allows it to be cut and sawed into sticks that can be used to create firmly rendered lines of the utmost precision, yet it is also friable enough to produce large-scale drawings of great tonal breadth and range. Although it has been known since antiquity, it was little used as a graphic medium until the sixteenth century, when artists recognized chalk's ability to render delicate transitions in tone in a smooth and seamless unity. (Michelangelo Buonarroti, Goldsmith's Designs, 1932.152; attributed to Agnolo Bronzino, Study of Bandinelli's "Cleopatra," 1932.145; Gustave Courbet, Portrait of the Artist with a Pipe, 1943.788).

Bodycolor: See gouache.

Brush drawing: A drawing made by applying a water-soluble pigment (or diluted ink) with a fine brush. The brush can be used to create very fine, linear strokes (Hans Leu the Younger, Pietà, 1936.125) or broad areas of wash. (Nicolas Poussin, Moses Defending the Daughters of Jethro, 1984.580).

Carbon black ink: An ink prepared by incorporating a black carbon pigment, derived from soot or charcoal, into water that has been mixed with a binding agent such as gum arabic or glue. As carbon is an inert material, the ink is chemically very stable, and its color tends not to change over time. (John Hamilton Mortimer, Salvator Rosa, 1990.56).

Cartoon: A full-size preparatory drawing for a painting, fresco, tapestry, or embroidery pattern. In the case of a fresco, the completed cartoon would be placed on the wet plaster of the wall and the outlines pricked or incised through the paper. Usually a fine black powder would be pounced, or rubbed through the holes or incised lines, leaving an outline of the design on the surface beneath. To prevent the cartoon from being ruined through contact with the damp plaster, artists would often prick the outline of their original drawing onto another sheet, which would in turn be used for any direct contact with the fresco. (Guido Reni (?), Diana, 1920.42; Giulio Campi, St. Jerome with the Animals, 1994.138). An auxiliary cartoon is a full-sized study for a significant detail in the composition, such as a head, based upon outlines traced from the complete cartoon to a separate piece of paper. The artist would usually work up the auxiliary drawing in some detail, so that it could serve as a guide or model when he came to paint the corresponding passages in the painting or fresco.

Chalk: See black chalk, red chalk and white chalk.

Charcoal: A wood carbon formed by slowly heating bundles of twigs in airtight chambers, a process that produces charred wood rather than ash. Because charcoal is composed of large, almost weightless, particles and is both very fragile and friable, allowing it to be erased with even the gentlest of rubbing, it is most suited for broad, rapid preliminary sketching on canvas, panel, paper or wall. (Hans Burgkmair, Head of a Bearded Man Wearing a Turban, 1936.124; Hilaire-Germain-Edgar Degas, After the Bath, 1965.257). In order to obtain a more intense and durable black stroke, the charcoal was occasionally soaked in linseed or olive oil to create "oiled charcoal." (Bartholomeus Breenbergh, Reclining Male Nude (Study for "Venus Mourning the Death of Adonis"), 1996.303)

Chiaroscuro drawing: A manner of drawing by which the usual drawing method of applying dark strokes over light colored paper is reversed. Instead, the composition is defined by light values, such as white gouache, over a dark ground. The etymology of the word is the combination of the two Italian words chiaro, meaning light, and scuro, the word for dark. (Unidentified German artist, 16th century, Martyrdom of St. Barbara, 1957.4).

Collector's mark: A small, distinctive mark, usually composed of initials, a design, or a paraph, which collectors and museums apply as a stamp or by hand on a drawing to indicate ownership. A "Studio" or "Estate" stamp is a similar mark applied to drawings found within an artist's studio, often after the artist's death. The presence of a collector's mark on a drawing can help establish the history of the drawing's ownership, known as its provenance. Critical to any research on collectors' marks and provenance is Frits Lugt's Les marques de collections de dessins et d'estampes (Amsterdam, 1921, and supplement, The Hague, 1956), in which Lugt assigned a number to each of the collector's marks he had identified--hence the reference to a "Lugt number" for a drawing with a recognizable collector's mark. (Giovanni Agostino da Lodi, Head of a Smiling Youth, 1965.393; Polidoro da Caravaggio, A Sacrifice with Two Warriors Standing beside an Altar, 1969.12).

Conté crayon: Invented in 1795 by Nicolas-Jacques Conté in response to the short supply of graphite during the Napoleonic Wars, Conté crayons were a mixture of refined graphite and clay. The process of manufacture used less graphite and, by altering the proportion of lead to clay, allowed the degree of hardness of the crayon to be altered. Deficiencies in the quality of the natural chalks, particularly red chalk, appear to have been the impetus at the end of the eighteenth century for the production of Conté crayons from carbon black and iron oxide. Orange-red in color, and slightly less friable than natural chalk, these became known as sanguine Conté crayons. Since the late nineteenth century, many fabricated dry or waxy crayons have been referred to as "Conté crayon." (Georges Pierre Seurat, Woman Knitting, 1943.919 and The Barge, 1978.33).

Counterproof: A reversed copy of a chalk drawing created by passing the original drawing, together with a moistened blank sheet of paper placed on top of it, through a printing press. The pressure of the press, and the friable nature of the medium, cause the design of the original drawing to be duplicated, albeit in reverse, on the dampened piece of paper. Printmakers found the technique useful because they could work from a design that was the correct way around for engraving a copper plate. The process was also used to adhere or fix more friable media to the support. A characteristic of counterproofs is their flattened appearance, from having been passed through the press. (Hyacinthe Rigaud, Head and Counterproof of Head of a Man, 1951.104).

Crayon: Made in the form of sticks, crayons are composed of colored pigments combined with oily, fatty, or waxy binding media. The type and proportion of the binder within the overall mixture determines the consistency, hardness, texture and tenacity of the crayon. In the seventeenth and eighteenth centuries, the term was used to describe fabricated chalks made by mixing ground natural black or red chalk with some form of filler and binder, as well as charcoal that had been modified into drawing sticks by soaking them in oils and soaps. Because the binder is always greasy or oily, the stroke of a piece of fabricated chalk or other crayon is usually more homogeneous and intense than that of the drier and more friable mark left by natural chalk. Today crayon has become a generic term to describe any color stick made with an oily or greasy binder, such as lithographic or children's wax crayons. (Henri de Toulouse-Lautrec, Circus Rider, 1943.923)

Friable: An adjective used to describe the extent to which a dry drawing medium crumbles and flakes.

Gouache: Also referred to as bodycolor and opaque watercolor, the term was first used during the eighteenth century in France to describe the use of a translucent water-based paint that had been rendered opaque by the addition of white pigment or chalk bound together with a binding agent such as gum arabic. Contrary to watercolor's key characteristic of transparent luminosity, gouache is defined by its matte and opaque quality. Today's commercially available product known as gouache differs considerably from that used by earlier draftsmen. (Louis-Gabriel Moreau, Parc de Saint-Cloud, 1955.188; Henri de Toulouse-Lautrec, Trapeze at the Medrano Circus, 1934.34).

Graphite: A crystalline form of carbon that was used at first as either a lump or sharpened point set into a metal holder. Although one of the finest lodes of graphite was discovered in 1560 at Borrowdale, England, extraction of the mineral was so highly regulated that its continued high price prevented any widespread usage until the late seventeenth century. In 1662, Friederich Staedtler began to manufacture pencils in Nuremberg. The strokes produced by graphite leave a line that has a relatively dark metallic luster, similar to lead point. The early misidentification of graphite with lead was not to be scientifically disproved until 1779, by which time the misconception that lead and graphite are one and the same had already entered modern-day usage--hence the confused nomenclature of lead pencil. (Thomas Gainsborough, Landscape with Manor, 1993.238; Jean-Auguste-Dominique Ingres, Portrait of the Family of Lucien Bonaparte, 1943.837; Hilaire-Germain-Edgar Degas, Study for the Portrait of Julie Burtey, 1965.254).

Ground: See prepared paper.

Gum arabic: The natural secretion of the acacia tree, gum arabic is used as a general binding agent in many media, in order to improve the bonding properties of the ingredients of inks and watercolor, as well as to help hold pigment particles in suspension.

Hatching: One of the most common ways for an artist to suggest volume and depth or to depict shadow, by which closely drawn parallel lines are grouped together. In the case of cross-hatching, the parallel lines are crossed by other sets of lines, creating a dense gridlike pattern. (Albrecht Dürer, The Lamentation of Christ, 1965.339).

Heightening/Highlights: A common technique for emphasizing mass and volume, highlights are produced by applying a light-toned pigment, usually white gouache or white chalk, to the desired area of the drawing. (Lorenzo di Credi, Drapery Study, 1932.128; Veronese, Rest on the Flight into Egypt, 1965.430). A similar effect can also be achieved by scraping through the medium to reveal the white of the paper.

India or Chinese ink: A form of black carbon ink that has been mixed with gum and resin and then hardened and molded into dry ink sticks ready to be watered down. It was imported into Europe from China as early as the sixteenth century, when it was mistakenly believed to come from the Indies, which has resulted in the present-day confusion in nomenclature. Today we think of India ink as the bottled black ink used for both drawing and writing.

Ink: See bistre ink, carbon black ink, India or Chinese ink, iron-gall ink, and sepia.

Iron-gall ink: A black ink produced by crushing and soaking gall nuts in water so as to extract the tannic and gallic acids within the nuts. Ferrous sulfate and gum arabic are then added. Iron-gall is the ink most commonly used in European drawings from the fifteenth through the eighteenth centuries. When exposed to light, the ink can change in color from black to brown. Consequently, although today many old master drawings appear to have been drawn with brown ink, originally they would have been black. The natural acidity of the ink can also have a corrosive effect on the fibers of the paper, actually eating the paper away. There is at present no known preventative action that can be taken to halt the ultimately destructive effect of the ink. (Pier Francesco Mola, Sleeping Nymph Surprised by a Satyr, 1932.228; Rembrandt Harmensz. van Rijn, A Standing Old Man, 1965.213).

Lead point: A stylus of lead, or lead alloy, it is the only metal that will mark unprepared paper. With the two advantages of being easily erased and of producing only a faint line, lead point was used in the fifteenth and sixteenth centuries for preliminary sketching in preparation for a drawing in another medium. Lead point's propensity to become blunt very quickly limited its wider use.

Mat: Two pieces of cardboard or paperboard, preferably acid-free, that are hinged together with cloth tape. The top part of the mat has a window the size of the drawing cut into it, and the drawing is attached to the bottom board. The mat serves to protect the drawing, enhance its aesthetic qualities and, if matted to standard size, aid in the storage of the drawings in solander boxes or flat files. In the Drawing Department of the Harvard University Art Museums, works are matted from size 1 (14 in. x 18 in.) to size 5 (33 in. x 44 in.). Historically, drawings tended to be attached just to a piece of board known as a mount. Just as a collector's mark on a drawing can help establish a provenance, so occasionally can a mat or mount, as certain collectors placed their drawings onto mounts that were embellished and decorated in very particular ways. Among the most recognizable and refined are the mounts that were used by the eighteenth century French collector Pierre-Jean Mariette. One of the first collectors to mount his drawings to standard sizes, he presented them on card that had a complex decoration of a blue paper border, gold leaf, some framing lines, and sometimes a cartouche in pen and wash. (Gaspar Dughet, A Road through a Wooded Landscape, 1964.82)

Measurements: Drawings are usually measured in millimeters, height preceding width. The term sight size is used when the person measuring the work is unable to lay the tape measure close to the drawing, or when part of the drawing is hidden (by a mat or frame, for example) and the complete extent of the drawing cannot be discerned.

Medium: The actual material used in the drawing process, such as charcoal, metalpoint, or red chalk.

Metal nib pen: The metal pen was not widely used until the second quarter of the nineteenth century, when advanced techniques for stamping, bending, and grinding steel became available. (Henri Matisse, Lady with a Necklace, 1965.307).

Metalpoint: A stylus made from a relatively soft metal, such as silver, gold, or copper, that, when drawn across the surface of a sheet of prepared paper, will leave a thin deposit of the metal on the surface, producing a very fine gray line. As increased pressure on the stylus will not have any dramatic effect on the thickness or intensity of the line produced, the stylus would usually be cast so as to have a fine point at one end and a blunter point at the opposite end in order to change the width of line. It can be difficult to identify the precise metal used in a metalpoint drawing, although over time silverpoint oxidizes from gray to brown and copper will usually turn a greenish hue. Gold remains highly stable as the same dull gray trace. Metalpoint was used mainly in the fifteenth century, but it enjoyed a resurgence of popularity in the late nineteenth century and continues to have a devoted following among some contemporary artists. (Pietro Perugino, Music-Making Angel, 1936.120; Pavel Tchelitchew, Portrait of Frederick Ashton, 1959.165; Susan Schwalb, Strata #25, 1997.4).

Mount: See mat.

Paper: Most common support used by artists for drawing. Paper's basis is cellulose fiber, derived either directly from the plant or indirectly from rags, sailcloth, etc. Whatever the precise raw materials used, all paper was traditionally made from breaking down or macerating the vegetable matter into individual cellulose fibers. These fibers were mixed with water to form a soupy pulp, and were then scooped up with a wire screen set into a wooden mold (the screen may be made with different materials in different parts of the world, such as bamboo in China or grass in India). The pulp was leveled flat with a shake, and once the water had drained through the screen, an even deposit of matted fibers remained on the screen's surface. This matted deposit was then turned out onto a heavy woolen cloth or felt. Another felt was placed on top of the thin sheet of pulp, and stacks of pulp sheets and felts were then pressed to extract as much of the moisture left in the pulp as possible. The sheets were then hung to dry. At this stage, the paper was still "waterleaf," or like blotting paper. To harden the surface of the sheet and prevent ink bleeding into the sheet, the paper was sized, or coated with a hard gelatin layer. Colored paper, such as blue paper (Domenico Tintoretto, Nude Study for the Figure of Christ in "St Peter Receiving the Keys," 1997.206), was made either by starting with colored rags to make the pulp or by adding dye after the pulp was prepared. There are two main types of paper in the West: laid and wove. Laid paper (Jean Baptiste Greuze, Seated Nude Woman, 1965.290) was made with a screen of wires that left in the finished sheet the impression of the closely spaced vertical "laid" lines and the broadly spaced horizontal "chain" lines, creating a gridlike effect when the paper was held up to the light. One of the most important developments of papermaking came in the eighteenth century with the development of the wove paper mold surface. (Joseph Mallord William Turner, Simplon Pass, 1954.133). Here, the wire screen was made up of a very fine wire mesh, so tightly woven that few or no residual wire marks were visible in the finished paper. Their exact development remains something of a mystery, but the earliest wove papers were made for the printer John Baskerville by James Whatman of Kent, England, and first used in the printing of his Virgil in 1757. Often papermakers will identify their papers with a watermark.

Parchment: A very durable surface for writing or drawing, prepared from the skins of sheep, goats or (for higher-quality vellum) calves. One side of the sheet is usually pock-marked with hair follicles, although the other side's smooth surface allows a very fine line to be produced. Its high absorbency and ivory-colored tone gives a rich effect to any drawing. It was used principally before paper was readily available. (Unidentifired Venetian artist, 14th century, Designs for Silk Weaving and Embroidery, 1932.291; Albrecht Dürer, Proportional Study of a Standing Nude Male, 1932.375; Sir Edward Burne-Jones, Sir Galahad Riding Through a Mysterious Wood, 1943.672).

Pastel: Made by blending dry powdered pigments with a nongreasy liquid binding medium such as gum arabic. The resultant paste is usually rolled into a stick and then dried. A wide spectrum of pastel colors is possible, and by the eighteenth century, some artists endeavored to imitate the power and richness of oil painting through a coloristic and painterly style of draftsmanship, so that many of the finest pastels of the period are known as pastel paintings. Pastels were invented at the end of the fifteenth century in northern Italy, and it is thought that Leonardo da Vinci was the first artist to use them, although none of his pastel drawings are known today. (Federico Barocci, Study for the Head of Christ, 1986.535; Jean-Baptiste-Siméon Chardin, Portrait of the Painter Jean-Jacques Bachelieu, 1939.89; Hilaire-Germain-Edgar Degas, Two Dancers Entering the Stage, 1943.812; Odilon Redon, Head of a Young Woman, 1943.905).

Pen: There are three basic kinds of pen. See metal nib, quill, and reed.

Pencil: By the early seventeenth century, the term pencil was used to designate an instrument which held a piece of graphite, chalk, or charcoal. Also used to describe any pointed brush, it was not until the later nineteenth century that pencil became associated specifically with what we now use the term to define: a strip of graphite or ground-up graphite, compacted with a binder, contained within a cylindrical piece of wood or other suitable holder. Because of continued confusion in the term's use, the Harvard University Art Museums use the designation graphite rather than pencil.

Pouncing: See cartoon.

Prepared paper: A sheet of paper that has been prepared either with a ground (Cennino Cennini, in his artist's handbook of the fifteenth century, suggested multiple coatings of white lead and ground bone, usually tinted with a pigment, and tempered with glue size), or with just a layer of colored wash in order to alter the aesthetic effect of the sheet. Metalpoint drawings must be made on paper prepared with a ground, as the slight "tooth" of the ground's texture is necessary to scrape off a thin deposit of the metalpoint onto its surface, while the usual addition of a tint creates a middle-tone value for the drawing. This allows the artist to work up from the mid-tone and model volumetrically with white highlights and to work down toward a darker tone. Also, see chiaroscuro drawing. (School of Fra Angelico, Pilate Washing His Hands and Crucifixion, 1939.114–115; attributed to Domenico Morone, St. Christopher; verso: Madonna and Child, 1932.122).

Quill pen: Made from the scraped and cut feathers of birds such as the goose, swan, raven, or crow. The goose quill was the most commonly used, and those of the raven or crow were considered to produce the finest and most delicate strokes. The quill is very flexible anad versatile, resulting in free and lively drawings often characterized by sweeping, almost dancing flourishes and great variations in the width of the pen line. (Giovanni Battista Tiepolo, Rest on the Flight into Egypt, 1965.418)

Recto: For a loose sheet that is double-sided (i.e., has drawings on both sides of the sheet), the recto is the side that is considered to have the more important drawing or drawings. (Pablo Ruiz Picasso, A Mother and Child and Four Studies of Her Right Hand; verso: Self-Portrait, 1965.318). For a bound volume of drawings, the righthand page of an opening is known as the recto. The other side of the sheet is known as the verso.

Red chalk: Sometimes referred to by the French term sanguine, natural red chalk is a clay that gains its color from iron oxide, also known as hematite. The proportion of the hematite to the clay content determines the specific hue of the chalk, which can range from a very pale red to a burnt brownish orange. Red chalk can produce broad, soft, and fluent gradations of tone, and because it is less friable than black chalk, and thus unable to readily cover large-scale areas of paper with unbroken tone, tends to be used for drawings that are on a relatively modest scale. The first artist to realize its potential was Leonardo da Vinci at the end of the fifteenth century. Red chalk reached its apotheosis during the eighteenth century in France, where artists such as Jean-Baptiste Greuze and Jean-Honoré Fragonard displayed exceptional virtuosity and mastery of the medium. (Agostino Carracci, Head of a Wind God; verso: Reclining Male Nude, 1975.91; Andrea Boscoli, Annunciation, 1932.216; Jean-Honoré Fragonard, Woman Standing with Hand on Hip, 1965.276).

Reed pen: Made from the hollow grass from which it takes its name, the reed pen was the common writing instrument of antiquity. Its fibrous nature prevents the sharpened nib from retaining a fine point for any length of time, making it far less adaptable and responsive than the quill. It produces short, blunt, and sometimes scratchy strokes. (Attributed to Rembrandt Harmensz. Van Rijn, Portrait of a Man, 1953.28; Vincent van Gogh, Peasant of the Camargue, 1943.515).

Sanguine: See red chalk.

Sepia ink: A brown ink obtained from the dried ink sacs of cuttlefish and squid. The sacs were ground up and mixed with boiling water. The liquid was drained off and the remaining sediment was then ground very finely and mixed with gum arabic before being dried into cakes that, when mixed with water, resulted in a rich, dark brown ink. The term is often misused as a synonym for the brown ink of old master drawings. In fact, its use became widespread only with the development of semi-industrial production methods in the nineteenth century. (Attributed to Piotr Michalowski, An Artilleryman Leading his Horse into the Field, 1965.286).

Silverpoint: See metalpoint.

Sketchbook: A book that contains drawing paper for sketches. It differs from an album in that the drawings are not adhered into the book but drawn on the actual sheets. (Jacques-Louis David, Sketchbook No. 14: Studies for "The Coronation of Napoleon," 1943.1815.12; Sir Edward Burne-Jones, Sketch Book Containing Studies for Various Pictures, 1943.1815.18; John Singer Sargent, Sketchbook, 1937.7.12).

Squaring: To facilitate the transfer, and often the enlargement, of a design from a drawing to another surface, such as a canvas or panel, artists sometimes "squared" their drawings by placing a grid of vertical and horizontal lines over the design to be transferred. The drawing was then copied square by square to the other surface, which would also have been squared with an identical, but appropriately scaled, grid. (Jean-Auguste-Dominique Ingres, Portrait of Madame Delphine Ingres, 1954.110).

Stump: A tightly rolled coil of leather or paper used to rub a chalk, charcoal, graphite, or pastel drawing in order to create subtle shading and tonal effects by blurring the medium. (Jean Baptiste Camille Corot, Forest of Coubron, 1943.786; Eugène Delacroix, Portrait of Frédérick Villot, 1949.6).

Stylus: A point made of metal that has been used to write on wax or wooden tablets since antiquity. Draftsmen have traditionally used the stylus to copy a drawing onto another sheet of paper. By inserting a fine sheet of paper covered with dusted chalk between the drawing and the blank sheet of paper, or by rubbing chalk directly onto the back of the drawing, the image can be duplicated onto the other sheet through the simple pressure of drawing the stylus point around the outlines of the original sketch. (Domenico Beccafumi, Head of an Old Man, 1965.359). Renaissance draftsmen also used the stylus for preliminary underdrawings, as well as for squaring a drawing.

Support: The surface upon which the drawing is made, such as paper or parchment.

Trois crayons: A highly pictorial technique that combined the use of white, black, and red chalk within one drawing. It was especially favored by French artists of the eighteenth century, notably Watteau. (Jean-Antoine Watteau, Six Studies of Heads, 1965.336).

Underdrawing: Used to describe a preliminary drawing, often in charcoal, and usually on a painting's canvas or panel, in which the outlines of form or composition are sketched in preparation for detailed work in other media. Often draftsmen also made a preliminary underdrawing in graphite or black chalk, or with a stylus, before finalizing their design in another medium.

Vellum: See parchment.

Verso: The reverse or back side of a sheet of paper. The opposite of recto.

Wash: A technique using ink, usually diluted with water, applied with a brush. Although drawings can be made with wash alone, it is more often used in conjunction with line or contour drawings in pen and ink to depict areas of light and shade. (Andrea Boscoli, Christ in the Temple, 1961.114; Giovanni Battista Tiepolo: Rest on the Flight into Egypt, 1965.418).

Watercolor: While an ink is in effect no more than a solution of dye, watercolor is a dispersion of solid, albeit very finely ground, particles of colored pigments that remain in suspension through the effect of Brownian motion--the random movement of microscopic particles when suspended in liquids or gases, caused by the impact of the collision with each other and the molecules of fluid with which they are mixed. The most important characteristic of watercolor is its brilliancy, a result of its translucent nature, which allows the white surface of the paper to shine through. To extend its range of possible effects, artists often incorporated opaque pigments and gouaches in their watercolors. (James Thornhill, Design for a Ceiling, 1991.82; William Blake, Cain Fleeing from the Wrath of God, 1943.401; John Mallord William Turner, Simplon Pass, 1954.133; Winslow Homer, Sailboat and Fourth of July Fireworks, 1943.305).

Watermark: A mark visible within the paper when held up to the light. The watermark is made by sewing into the screen of the paper mold a wire impression of the desired mark. When the pulp is placed onto the surface of the screen, these raised wires leave an impression in the pulp such that the area above the wire design is thinner and more translucent, capturing the design of the watermark in the final sheet. Study of a sheet's watermark can provide useful information about the paper's date and place of manufacture. Important collations of watermarks include: C. M. Briquet, Les filigranes. Dictionnaire historique des marques du papier, 4 vols. (Paris, 1907); W. A. Churchill, Watermarks in Paper in Holland, England, France etc, in the XVII and XVIII Centuries and Their Interconnection (Amsterdam, 1935), and E. Heawood, Watermarks Mainly of the 17th and 18th Centuries (Hilversum, 1950). (John Singer Sargent, Study of Pine Cones, for "Classical and Romantic Art," Museum of Fine Arts, 1929.276).

White chalk: Primarily used to heighten drawings in other media. There are two types of natural white chalk: calcite or calcium carbonate, a soft and fairly brilliant white, and soapstone or stealite, a slightly harder, bluish white. (Pierre-Paul Prud'hon, Reclining Male Nude, 1943.886; Thomas Gainsborough, Wooded Landscape with Herdsman, Cows, and Church, 1979.46).