The Department of Thickness and Gauge, established by the Brennholt Institute of Applied Taxonomy as its third department, records objects whose useful identity is a single small dimension, usually under 3 mm, and whose makers have never agreed on a way to report it. The department's first records cover guitar picks, playing cards, drinking straws and bubble wrap.
The Institute's observation is that thin objects are sold by a number which each maker defines for itself. A pick marked medium is a different thickness in the hands of different makers, and a card stock described by weight is not described by thickness at all.
The department records an object when three conditions hold. First, the object is made in large series. Second, its principal dimension is a thickness or a gauge. Third, no published standard fixes that dimension. Where a real standard exists, the department cites it and does not alter it. Wire gauge is the standing example: the Standard Wire Gauge and American Wire Gauge are real and are used as published, as on the wire gauge explained page.
The method is the same one used on the paperclip, set out on the seven-class system page, and the department applies it without change.
Three units appear throughout. The millimetre, for anything over 1 mm. The thousandth of an inch, called a thou or a mil, for things under 1 mm, where one thousandth is 0.0254 mm. And the micrometre, one thousandth of a millimetre, for films. The conversions are exact and are not the Institute's: 1 inch is 25.4 mm by definition.
| Thousandths of an inch | Millimetres |
|---|---|
| 5 | 0.127 |
| 10 | 0.254 |
| 12 | 0.305 |
| 20 | 0.508 |
| 40 | 1.016 |
The department's first pages are these:
The department's records of drinking straws and bubble wrap follow once measured.
The Institute offers three reasons from its first measurements. A thin object is cheap, so nobody has been paid to standardise it. A thin object is hard to measure without a micrometer, so buyers rely on the maker's word. And a thin object is described by feel, with words such as light, medium and heavy, which carry no unit. The department treats the missing unit as the central finding.
All department measurements are taken with a hand micrometer reading to 0.01 mm, on five samples per object, at a different point on each, and the mean is reported to two decimal places. The Institute reports the spread alongside the mean, since for thin objects the spread is often as informative as the mean. The department does not report a measurement taken from a single sample.
The department sits beside the Department of Office Fastening and the Department of Industrial and Domestic Fastening, and shares their method. The Institute's general account of the unclassified is on the objects classified by none page.
The review panel is divided on whether weight per area should be a department measure alongside thickness. One member holds that for card and paper it is the more honest figure. The majority hold that thickness is directly measurable and weight is not, and the department proceeds on thickness. The question is open and is noted on each affected page.