The palm may be either one of two obsolete non-SI units of measurement of length.
In English usage the palm, or small palm, also called handbreadth or handsbreadth, was originally based on the breadth of a human hand without the thumb, and has origins in ancient Egypt. It is distinct from the hand, the breadth of the hand with the thumb, and from the fist, the height of a clenched fist.[1] It is usually taken to be equal to four digits or fingers, or to three inches, which, following the adoption of the international inch in 1959, equals exactly 7.62 centimetres. It is today used only in the field of biblical exegesis, where opinions may vary as to its precise historic length.
In other areas, such as parts of continental Europe, the palm (French: palme, Italian: palmo) related to the length of the hand, and derived from the Roman great palm, the Latin: palmus major.
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On surviving Ancient Egyptian cubit-rods, the royal cubit is divided into seven palms of four digits each. Five digits are equal to a hand, with thumb; and six to a closed fist.[2] The royal cubit measured approximately 525 mm,[3] so the length of the ancient Egyptian palm was about 75 mm.
| Name | Egyptian name | Equivalent Egyptian values | Metric equivalent |
|---|---|---|---|
| Royal cubit | meh niswt | 7 palms or 28 digits | 525 mm |
| Fist | 6 digits | 108 mm | |
| Hand | 5 digits | 94 mm | |
| Palm | shesep | 4 digits | 75 mm |
| Digit | djeba | 1/4 palm | 19 mm |
The ancient Roman system of linear measurement was based on the pes or standard Roman foot,[4] which was divided into 16 digits or, in later times into 12 uncia or pollex, Roman inches.[5] According to the Encyclopédie, there were two types of palm in ancient Rome: "the great palm was the length of the hand and contained twelve digits or nine inches; and the small palm, across the hand, was of four digits or three inches".[6] Smith gives this table of equivalence between the smaller Roman units of length, to which approximate modern metric equivalents are added:[5]
| Name | Latin name | Equivalent Roman value | Metric equivalent | |||
| Digit | Inch | Palm | Foot | |||
| Digit | digitus | 1 | 3⁄4 | 1⁄4 | 1⁄16 | 18.5 mm |
| Inch | uncia orpollex | 11⁄3 | 1 | 1⁄3 | 1⁄12 | 24.6 mm |
| Palm | palmus minor | 4 | 3 | 1 | 1⁄4 | 74 mm |
| Great palm | palmus major | 12 | 9 | 3 | 3⁄4 | 222 mm |
| Foot | pes | 16 | 12 | 4 | 1 | 296 mm |
| Foot + palm | palmipes | 20 | 15 | 5 | 11⁄4 | 370 mm |
| Cubit | cubitus | 24 | 18 | 6 | 1 1⁄2 | 444 mm |
| Metric equivalents are based on the estimated value 1 pes = 296 mm[4] | ||||||
In English usage, the palm or handsbreadth is generally taken to be three inches. Some confusion between the various types of hand measurement, and particularly between the hand and the handsbreadth, appears to have persisted in Britain for several centuries after the hand was standardised at four inches by a statute of King Henry VIII in 1541.[7] Phillips's dictionary of 1706 gives four inches for the length of the handful or hand, but three inches for the handsbreadth;[8] Mortimer gives the same, three inches for the Hand's-breadth, and four for the "Handful, or simply, Hand",[7] but adds
"The hand among horse-dealers, &c. is four-fingers' breadth, being the fist clenched, whereby the height of a horse is measured"
thus equating "hand" with both the palm and the fist. Similarly, Wright's 1831 translation of Buffon mentions "A hand breadth (palmus), the breadth of the four fingers of the hand, or three inches",[9] but the Encyclopædia Perthensis of 1816 gives under Palm (4): "A hand, or measure of lengths comprising three inches".[10]
In English measurements, the handsbreadth has mostly fallen out of use.
In various parts of Europe and the Mediterranean, the palm was based on the length of the hand rather than the width. Greaves in 1647 gives equivalents for three kinds of palm, the Roman palmo di Architetti or architect's palm, the Roman palmo del braccio di mercantia or commercial palm, and the Genoa palm.[11] In 1795 (and again in 1815) these values were reported by Charles Hutton:[12][13]
| City | Inches | Metric equivalent |
|---|---|---|
| Rome | 87⁄24 | 211 mm |
| Naples, as reported by Riccioli | 8 | 203 mm |
| Naples, as reported by others | 87⁄12 | 218 mm |
| Genoa | 93⁄4 | 248 mm |
| Morocco and Fez | 71⁄6 | 182 mm |
| Languedoc and some other parts of France | 93⁄4 | 248 mm |
| Metric equivalents are approximate, and do not take account of possible regional variations in the inch | ||
Palaiseau, writing in 1816, gives these metric equivalents for the palme or palmo:[14]
| City | Lignes | Metric equivalent |
|---|---|---|
| Florence (for silk, p.146) | 131.63 | [297] mm |
| Florence (for wool, p.146) | 128.38 | 289.6 mm |
| Genoa (cloth measure, p.148) | 106.9 | 241.1 mm |
| Genoa (linear measure, p.91) | 107.43 | 242.3 mm |
| Livorno (for silk, p.157) | 128.41 | 289.7 mm |
| Livorno (for wool, p.157) | 130.08 | 293.4 mm |
| Malta (cloth measure, p.160) | 114.49 | 258.3 mm |
| Malta (linear measure, p.98) | 115.28 | 260.0 mm |
| Palermo (cloth measure, p.168) | 107.16 | 241.7 mm |
| Portugal (p.109) | 96.36 | 217.4 mm |
| Rome (cloth measure, p.173) | 109.52 | 247.1 mm |
| Rome (linear measure, p.111) | 99 | [223] mm |
| Metric equivalents in the source here rounded to 0.1 mm | ||
According to a sign displayed in Pernes-les-Fontaines, Vaucluse, France, a palme or palm of 246.1 mm was in use there in the 17th century, and was one eighth of a canne. The same proportion applied in Malta, at Rome and at Palermo.[14]