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Behind the Scenes: Special Collections and Archives Calculator

By Special Collections & Archives Technical Services on July 1, 2016 6:12 PM | Permalink

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Introducing the Rebel Archives Calculator

The University of Nevada, Las Vegas University Libraries Special Collections Division is excited to introduce the Rebel Archives Calculator, a handy online tool developed by application programmer Carlos Lemus (UNLV undergraduate student in Computer Engineering) to help us better understand the physical extent of our archival collections. The Calculator simultaneously reports collection extents in cubic and linear feet, and includes a function that enables download of results as an Excel sheet. The Calculator auto-populates fields for the more standard sizes and measurements of archival boxes, flat folders, and vertical files found at UNLV, and includes multiple fields for users to enter “custom container” dimensions. UNLV is sharing this early version of the Calculator with the community. The calculator works well from the devices we've tested, but downloading and saving a collection's extent summary from an iPad can be a bit tricky--see Rebel Archives Calculator iPad tips

Why the new tool?

Knowing the extent of our holdings is important—internally, tracking the growth of the physical footprint of our holdings can inform space planning and collection development, and externally, the volume of materials in a particular collection helps researchers roughly gage how much information we might have on a specific subject. The results of a recent archival collection survey at UNLV emphasized the shortcomings of linear feet as a unit of measure, prompting the current move toward cubic feet. The Rebel Calculator was developed to meet our practical need to measure in cubic footage, while also enabling UNLV Libraries to report in linear footage to external agencies if necessary. While UNLV Special Collections found other archival calculators helpful and inspirational, we did not find one that met our need to calculate space occupied in both cubic and linear footage.

Why cubic feet?

Libraries traditionally measure physical holdings of books and printed material in linear feet, which is a logical approach for measuring library shelves lined with fairly standard-sized volumes of books, serials, and media.

(Editions of Hoyle’s Games, Taxe Collection of Historical Gaming Books, UNLV Libraries Special Collections)

Archival holdings and containers, however, come in wildly different shapes and sizes: tiny custom boxes, media boxes, document boxes, record storage cartons, oversized folders, tubes, architectural models, and all manner of three-dimensional objects. As a unit of measure, cubic footage captures all the dimensions of a container or object rather than the single dimension captured by linear footage.

Employing the professionally accepted method of using linear feet as the unit of measure, which is based upon how items are oriented on a shelf (or floor), very different sized items might have identical measurements, as demonstrated by a 1940s Jennings slot machine (16 x 19 x 61 inches) stored with the 19-inch side facing out; a flat archival storage box (19 x 25 x 2.5 inches) stored with the 19-inch side (width) facing out; and a rolled architectural drawing (19 x 1 x 1 inches), which would traditionally be measured by its 19-inch length rather than its diameter.

archival box and rolled drawing

Nineteen inches converts to approximately 1.58 linear feet; representing the diverse items pictured above as 1.58 linear feet each does not adequately represent the space they actually occupy.  Calculating space occupied using cubic feet reveals the very real difference between the items: the slot machine at 10.73, the flat box at 0.69, and the roll at 0.01 cubic feet.

Measurements and mathematical calculations

The mathematical calculations used for the Rebel Archives Calculator have been tested and refined by Sal Veltre (UNLV undergraduate student in Accounting) in collaboration with programmer Carlos Lemus. While the decimal points behind the scenes more or less run into infinity, the user interface displays results to two decimal points. The Rebel Calculator rounds numbers only at the final sum when the collection extent is totaled (rather than rounding measurements incrementally in the individual fields where each box type is recorded, as done by some calculators). To accommodate a variety of practice, rounding numbers up or down any further is left to the discretion of the user.

Salvatore Veltre III browsing the stacks in UNLV University Libraries, 2016

(Salvatore Veltre III browsing the stacks, UNLV University Libraries, 2016)

Standard archival box sizes differ from one vendor to another, and our shelves are filled with “standard” sized boxes that actually vary a fraction of an inch one from another—since it is impractical to represent every variation exactly, the container dimensions listed in the Rebel Calculator reasonably represent the most prevalent archival box types/sizes found at UNLV.  It is important to note that we derived container dimensions from the exteriors of containers and included the box lids in our measurements to account for physical space occupied (rather than the interior capacity of boxes as listed on vendor websites).

Calculating cubic footage

Behind the scenes, standard formulas are applied to determine the cubic footage of each container type and the result is then multiplied by the number of containers of that type:

cubic foot = ( L/12  x  W/12  x  H/12 )  x  number of containers

For drawings, maps, and other rolled materials, calculations executed by the Rebel Calculator are based on a rectangular box rather than a cylindrical container.  Employing a single formula for the different types of containers that potentially house rolled materials normalizes the measurements for rolled materials and simplifies the act of measuring them.

tubes rolls boxes

When stacked, tubes and rolls not stored in boxes often leave unusable empty space between items and essentially occupy the same amount of space as their boxed equivalents, making the cubic foot formula for rectangular boxes quite appropriate for representing the space occupied by rolls and tubes.

Calculating linear footage

The Rebel Calculator uses the width of each container as the variable that determines linear footage—this follows accepted archival practice, which assumes standard document boxes and record cartons are generally placed on the shelves with the short side (width) facing out.

linear foot = ( W/12 )  x  number of containers

It should be noted that our decision to compute linear footage by measuring width rather than length marks a point of departure from other archival calculators when it comes to the measurement of rolls, flat boxes, and oversize flat folders. Furthermore, assuming the width/short side of a container is facing out on a shelf does not always hold true for oversized flat boxes nor for rolled materials, rendering our linear footage calculations for these types of boxes inconsistent. UNLV Libraries is not overly concerned with this variation in the linear footage calculation, accepting that linear footage is by nature less precise than cubic footage, and preferring instead to focus efforts on more accurately measuring our holdings through cubic footage.

Give the Rebel Calculator a try!   Comments are welcome: speccoll.techserv@unlv.edu

The calculator functions best in Chrome and Firefox. To download and save a collection's extent summary from an iPad see : Rebel Archives Calculator iPad tips