Approximate measures are units of volumetric measurement which are not defined by a government or government-sanctioned organization, or which were previously defined and are now repealed, yet which remain in use.[1][2][3]
It may be that all English-unit derived capacity measurements are derived from one original approximate measurement: the mouthful, consisting of about 1⁄2 ounce, called the ro in ancient Egypt (their smallest recognized unit of capacity).[4][5] The mouthful was still a unit of liquid measure during Elizabethan times.[6] (The principal Egyptian standards from small to large were the ro, hin, hekat, and khar.)[7]
Because of the lack of official definitions, many of these units will not have a consistent value.
The vagueness of how these measures have been defined, redefined, and undefined over the years, both through written and oral history, is best exemplified by the large number of sources that need to be read and cross-referenced in order to paint even a reasonably accurate picture. So far, the list includes the United States Pharmacopoeia,[10][11][12] U.S. FDA,[13] NIST,[14][15][16] A Manual of Weights, Measures, and Specific Gravity,[17] State Board Questions and Answers,[18] MediCalc,[19] MacKenzie's Ten Thousand Receipts,[20] Approximate Practical Equivalents,[21] When is a Cup not a Cup?,[22] Cook's Info,[23] knitting-and.com.,[24] and Modern American Drinks.[25]
Dashes, pinches, and smidgens are all traditionally very small amounts well under a teaspoon, but not more uniformly defined. In the early 2000s some companies began selling measuring spoons that defined a dash as 1⁄8 teaspoon, a pinch as 1⁄16 teaspoon, and a smidgen as 1⁄32 teaspoon.[26][27] Based on these spoons, there are two smidgens in a pinch and two pinches in a dash. However, the 1954 Angostura “Professional Mixing Guide” states that “a dash” is 1/6th of a teaspoon, or 1/48 of an ounce, and Victor Bergeron (a.k.a. Trader Vic, famous saloonkeeper), said that for bitters it was 1⁄8 teaspoon, but 1⁄4 fl oz for all other liquids.[28]
| Fluid Measures | |||||||
|---|---|---|---|---|---|---|---|
| Unit | Abbrev. | Definition 1 (c. 1885) |
Definition 2 (c. 1905) |
Definition 3 (c. 1975) |
Definition 4 (c. 2015) |
Traditional Binary Submultiple Fl. Oz. |
Binary Submultiples |
| hint | 1⁄128 tsp[29] | 1⁄1024 | 2 hints = 1 drop | ||||
| drop | dr., gt., gtt. | 1⁄8 to 11⁄2 minim or 5 centigrams[10] | 1⁄64 tsp[30] | 1⁄512 | 2 drops = 1 smidgen | ||
| smidgen | smdg.,[25]: 12 smi. | 1⁄32 tsp | 1⁄256 | 2 smidgens = 1 pinch | |||
| pinch | pn. | 1⁄8 tsp | 1⁄16 tsp | 1⁄128 | 2 pinches = 1 dash | ||
| dash | ds. | 1⁄8 tsp | 1⁄64 | 2 dashes = 1 saltspoon | |||
| saltspoon (scruple-spoon,[25]: 12 tad[30]) |
ssp.,[31][32] sp.,[32] scrsp.[25]: 12 | 1⁄4 tsp[23] | 1⁄32 | 2 saltspoons = 1 coffeespoon | |||
| coffeespoon (barspoon) |
bsp.[33] | 1⁄2 tsp[23] | 1⁄16 | 2 coffeespoons = 1 teaspoon | |||
| teaspoon (kitchen spoon, splash) |
tsp. or t. | 1 fluid dram or 5 mL[10] most common size: 80 minims or 3 mL [17] |
1 fluidrachm or 4 mL,[11] or 3.75 mL[18] (actual range: 4.6–5.5 mL [12]) |
1⁄3 tablespoon or 1⁄6 fl oz | 1 fl dram or 5 mL,[13] 1⁄6 fl oz,[15] 11⁄3 fl dr | 1⁄8 | 2 teaspoons = 1 dessertspoon |
| dessertspoon | dsp., dssp. or dstspn. | 2 fluid drams or 10 mL[10] most common size: 2 1⁄2 fl dr or 10 mL [17] |
2 fluidrachm or 8 mL,[11] or 7.5 mL[18] (actual range: 8.4–10.4 mL [12]) |
2 fl dram or 8 mL[13] | 1⁄4 | 2 dessertspoons = 1 tablespoon | |
| tablespoon (mouthful) | tbsp. or T., rarely tbls. | 1⁄2 fluid ounce or 20 mL[10] most common size: 5 fl dr or 20 mL [17] |
4 fluidrachm or 16 mL,[11] or 15 mL[18] (actual range: 12.8–15.6 mL [12]) |
1/2 fl oz or 15 mL[13][15] | 1⁄2 | 2 tablespoons = 1 handful | |
| handful (fluid ounce, finger) |
m. (for manipulus)[34] | 1 fl oz[35][36][37] | 1 | 2 handfuls = 1 wineglass | |||
| wineglass (glassful) |
wgf.,[19] | 2 fluid ounces or 60 mL,[10] w-gl.[25]: 12 | 2 | 2 wineglasses = 1 teacup | |||
| teacup | tcf.[19] | 4 fluid ounces[10] | 4 | 2 teacups = 1 coffeecup | |||
| coffeecup (tumbler, kitchencup) |
8 fluid ounces[15] | 8 | 2 coffeecups = 1 jug | ||||
| jug (pint) |
16 | 2 jugfuls = 1 pitcher | |||||
| pitcher (quart) |
ptch. | 32 | 2 pitchers = 1 pottle | ||||
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Who would have thought that the units of measure "the pint" and "the quart" are based on "the mouthful" (Klein, 1974, The World of Measurements: Masterpieces, Mysteries, and Muddles of Metrology.).
The smallest recognized unit of volume was the ro, a mouthful. It was reckoned that five mouthfuls made one sixty-fourth of a heqat so there were 320 ro to one heqat.
A fairly clear line of descent has thus been traced from the jigger, or handful, of Elizabethan England to the customary unit for dispensing the "firewater" that is the most prevalent drug used in our own time and culture, nearly four centuries later. In the United States the half jigger, sometimes called a pony, is half again the Elizabethan mouthful.
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