5D | MEASURING

HOLLY YOUNG (REVISED BY JOHN E. SIMMONS AND TONI M. KISER)

MEASUREMENTS ARE basic to museum registration processes. They are a vital part of the initial record of an object entering a museum and serve as a baseline for publication, exhibition, and storage. Size, weight, and color should be recorded systematically. Object measurements and weights are used to determine space and material requirements for exhibit cases, storage furniture, and packing crates. Measurements can help track the condition of an object subject to breakage or dimensional changes. Standard procedures for object measurement should be defined to ensure consistency of use by individual staff members over time.

MEASUREMENT SYSTEMS

Many scientific disciplines and most countries other than the United States use the metric system, as do many US institutions. For those museums that wish to use the English system, it is best practice to record measurements in metric units as well.

An important issue to consider is the amount of precision necessary in the object measurements. In many disciplines, metric measurements are expressed in centimeters to one decimal place (or the nearest millimeter) and English measurements are expressed in inches to within 1/16 of an inch. If a measurement falls between significant increments, the reading is rounded up to the larger measurement. If increased precision is necessary, measuring implements must be selected that are more fine-tuned.

The equipment used to measure objects ranges from simple linear measuring devices to instruments that allow electronic data capture and record information directly into an electronic file. Select the kind of equipment that will be most useful for the institution, based on three major considerations: (i) the types and sizes of objects to be measured; (ii) the measurement system used; and (iii) and the amount of precision necessary.

Linear measuring devices, such as rulers, metersticks, and measuring tapes, are the most widely available and frequently used pieces of measuring equipment. They are particularly well-suited to measuring two-dimensional objects and large objects. Metal measuring tapes are the most durable but have the potential to damage the object being measured. Plastic measuring tapes have the advantage of being flexible but are easily stretched or warped, resulting in inaccurate measurements. Cloth measuring tapes and flexible fiberglass tapes are more durable than plastic and, although they can become distorted, are a good compromise.

Calipers and osteometric boards, which are useful for measuring 3-D objects, consist of a linear measuring scale with one stationary and one sliding arm, which are used to measure the distance between two points on an object. These devices yield a more accurate measurement of a 3-D object than is possible using a straight rule. Digital calipers can be used to record measurements directly into electronic data files. Calipers with both straight and pincer arms are useful; pincers are especially good for recording thickness at a particular point on the object.

Templates and gauges can be used for more precise measurements, if necessary. Color should be described using color matching systems (e.g., Munsell or Pantone). When weighing is necessary, there are a variety of electronic and spring-loaded scales and balances from which to choose. A sturdy, easy-to-calibrate triple beam balance is useful for small- to medium-sized objects. Tiny objects will require a more delicate scale or balance.

Measurement Procedures

To establish institutional measurement procedures, it is prudent to work with curatorial staff in various disciplines because they will know the standards used in their fields. Although interobserver variability can never be eliminated, it can be reduced, making measurements more reliable. Keep equipment clean, calibrated, and in good working condition and store it properly after use. Measuring equipment should be calibrated on a regular basis (as often as needed) and should be checked before use. More sophisticated and complex equipment must be calibrated more frequently.

Use particular care when handling objects for measurement. More than simply moving an object, measuring requires a certain amount of manipulation of both the object and the measuring device. For this reason, it is prudent to remove rings, watches, bracelets, pendant necklaces, or other items that may inadvertently come in contact with the object. Hands should be free of lotion or soap residues. Cotton or nitrile gloves should be worn, as appropriate (see CHAPTER 5B, “Object Handling”). Make sure that an adequate amount of space is cleared and prepared for the activity and that any necessary auxiliary materials, such as padded supports, are readily available before moving the object. When using calipers, be careful not to crush the object or damage delicate edges by applying too much pressure. To record measurements, use a pencil rather than a pen or marker (both of which can inadvertently leave a permanent mark on the object).

Two-Dimensional Objects

In general, height and width (or length) are the two basic measurements taken for flat objects. Thickness (or depth) should also be recorded for framed or mounted objects. By standard practice, height precedes width.

• Paintings and other flat, rectangular objects— For square or rectangular formats, make at least two measurements from the back of the work in each direction, one at the middle, the other at an edge; record the larger measurement, if any variation occurs. Record the diameter for a circular painting or object, and the length of two axes for oval or rhombus-shaped objects. Measure the thickness of paintings on heavier supports, such as panels, and those with auxiliary supports, such as stretchers or cradles. If the frame prevents such measurements, record a sight measurement of the painting sur face and the dimensions of the frame, and indicate them as sight measurements.
• Textiles—This category includes two-dimensional objects such as flags, rugs, wall-hangings, and bedding. Simple woven textiles should be measured along the warp (stationary element) and the weft (moving element). Be clear as to whether or not fringe, borders, or tassels are included in the overall measurement; in any case, their length or width should be measured and noted separately. Hand-woven pieces may have the number of warps or wefts per unit of measure. More complex pieces, such as flags or quilts, should be measured in two dimensions according to their orientation in use. If a textile has a significant pile or loft, include this as a third dimension.
• Works on paper—Unless otherwise indicated, works on paper are measured along the left side for height, and the lower edge for width. In addition to measuring the paper support, dimensions should be taken of the design area and plate mark, if the piece is a print. Historic documents require similar measurements, including the area covered by text. If the paper support has been hinged and matted, consider it an auxiliary support and take the measurements of the mat as well.

Three-Dimensional Objects

Generally, the overall height, length or width, and depth or thickness of these objects should be measured. Make these measurements at the point of greatest dimension. It may be practical to take a few additional measurements that are specific to the type of object and that may be important to the identification, display, or use of a particular object.

• Amorphous objects—At times, objects with odd shapes and no true orientation (e.g., clumps of charred botanical materials, clods of fired adobe, crumpled pieces of metal, slag, fire-cracked rock) must be measured. Place the object on a flat surface in its most stable position, and take measurements in three dimensions from that orientation. Record the orientation or draw a simple diagram. A weight is also useful for amorphous specimens.
• Boxed collections—Archival paper documents, with the exception of large format materials, are usually measured by a linear dimension (e.g., centimeter, meter, inch, foot). Large format documents, such as maps and plans, are measured by storage volume. Some repositories measure all archival collections by volume, specifically by cubic feet. This figure is determined from the compounded exterior dimensions of the storage containers. Large collections of objects and samples that are stored in boxes are similarly measured in cubic feet.
• Coins—By convention, coins are measured in millimeters; if an institution uses the English system, a conversion should be made. Measure the diameter and the thickness of the coin. For coins with central perforations, give the internal dimensions of the perforation.
• Furniture—The measurements for furniture may be less ambiguous if expressed as height, side-to-side, and front-to-back dimensions. Because dimensions may vary, take several measurements and record the largest. ln addition to the basic measurements, measuring the height and depth of seats, and the length of aprons, table leaves, and legs may assist in developing exhibit groupings and identifying particular pieces. Because furniture is susceptible to dimensional changes, areas of loss, decay, cracks, and splits should be noted and measured.
• Historic hardware and tools—Record the weight of hardware in addition to gauge. Indicate measurements of handles, including circumference, and working edges.
• Natural history specimens—A wide variety of materials fall under this classification. In addition to covering the entire spectrum of animal, vegetable, and mineral, it includes auxiliary items such as nests, specimens in various stages of growth, and variously preserved specimens, including taxidermy mounts and dried or cross-sectioned specimens. It is advisable to consult the individual curatorial department for guidance. In general, overall dimensions and often weight will be useful. Specimens in containers may have the container dimensions or volume recorded, as well.
• Personal items—For clothing, in addition to overall dimensions, tailoring measurements are usually taken, such as inseam length or inside waistband (figure 5d.1). If a standard size is marked on the object, this can be recorded, too. Accessories, such as hats or bags, should have careful measurements made of applied parts that may be subject to damage, especially feathers or trim. Component parts of jewelry should be measured—for example, the watchband or chain, as well as the watch itself. Measure diameters and restrictions for objects of personal adornment such as bracelets or labrets.
  

  FIGURE 5D.1 MEASURING. CREATED BY AUTHOR.

• Prehistoric tools—Record basic measurements of projectile points, blades, axes, etc. For artifacts that were originally hafted, also measure hafting features, such as grooves, holes, and tangs. The hollowed-out area of artifacts such as grinding stones or mortars should be measured. Elongated artifacts such as awls, needles, or shafts should be measured for length, and diameters or thicknesses at mid-shaft and at the base.
• Sculpture—Record standard dimensions; include the pedestal or other support only if it is an integral part of the sculpture. For portraits, record measurements from the proper aspect (e.g., from the depicted person’s left or right, not the viewer’s).
• Toys—Record standard dimensions. Toys made of separate components should have a count of the pieces and a range of measurements given.
• Vessels—The objects in this category can be made from many different materials, including botanical materials, ceramic, glass, and stone. For bottles and jars, measure the height and maximum diameter. Other measurements that may be taken include the orifice diameter and the neck height, where the neck is specifically delineated. Similarly, bowls should be measured for height and maximum diameter. Occasionally wall thickness is measured. At least three overall measurements should be taken for eccentric forms and other vessels such as scoops or effigies.
• Weapons—In addition to basic measurements, record the length of the barrel and size of the bore for firearms. Weapons with a cutting edge should include measurements of the blade and haft.

Images and Other Machine Produced or Machine-Readable Media:

• Static images—If matted and framed, these objects should be measured as flat works of art. If they are unframed, record the support and image size for positives. Record film size, length of strip (when applicable), and a count of the individual images for negatives. For slides and transparencies, give a count of the images and the size of the mount. Because these are easily duplicable, have a policy on whether or not counts should reflect unique images or include all copies of the image.
• Moving images—Film and video can be measured in a number of ways, including length in feet or in playing time. Generally, the format and size of the reel or cassette are recorded.
• Sound recordings—Although there are many formats, including historic cylinder and wire recordings, tapes of varying sizes and formats, and disks of different media and speeds, sound recordings are generally measured as moving images.
• Digitized information—In addition to the above methods of measuring, digitized information can be measured by the byte. Other measures, such as the number of digitized images, should also be recorded. •

Thanks to Laura Andreu, Noelle McClure, and Lindsey Vogel.