of payments: without delay
This expression refers to the fingernail and might originally have alluded to drinking fair and square. A clue might be provided by the French phrase payer rubis sur l’ongle (literally to pay ruby on the fingernail), which means to pay exactly what is due.
(A variant, used by prostitutes, was rubis sur pieu, which means cash on the bed – le pieu is slang for le lit, the bed).
Payer rubis sur l’ongle is a variant of the obsolete phrase faire, or boire, rubis sur l’ongle (literally: to do, or drink, ruby on the fingernail) which meant to drink out so that the inverted tankard leaves only one red drop of wine, like a ruby, on one’s thumbnail. A variant of this is found in A Dictionarie of the French and English Tongues (1611), by Randle Cotgrave:
Goutte sur l’ongle. Boire la goutte sur l’on [sic]. To drinke all but a drop to couer the nayle with.
(In Le Miroir de mariage, the French poet Eustache Deschamps (1340-1406) wrote that a wet nurse’s milk is of good consistency if one drop of it “sur l’ongle se tiengne”, “on the fingernail stands”.)
In The Idioms of the French and English Languages (1751), Louis Chambaud translates faire, or boire, rubis sur l’ongle as to drink supernaculum.
The obsolete English word supernaculum is a pseudo-Latin adverb meaning to the very last drop. It is a rendering of German auf den Nagel, on to the fingernail, in the phrase auf den Nagel trinken, which means to drink off to the last drop. However, when the English word supernaculum was first used (and explained), the practice was attributed to the French. The English pamphleteer Thomas Nashe (1567-circa 1601) wrote the following margin note in Pierce Penilesse his supplication to the diuell (1592):
Drinking super nagulum, a deuise of drinking new come out of Fraunce: which is, after a man hath turnde vp the bottom of his cup, to drop it on hys nayle and make a pearl with that is left which, if it slide & he cannot mak stand on, by reason thers too much, he must drinke againe for his penance.
The image on the nail to refer to a payment made without delay is ancient, and the English phrase seems to be an adaptation of Anglo-Norman sur le ungle or of Latin super unguem.
According to merchant or fair law, it appears to have been the custom at Ipswich in 1291 for traders not to make writings or tallies if two witnesses present could prove that the agreement was to pay on a near day “ou freschement sur le ungle” (“or freshly on the nail”). The original Anglo-Norman text is:
En meyme la manere si un marchaunt vende sa marchaundise a un autre marchaunt a payer a brefe jour ou freschement sur le ungle, en quel cas marchauntz ne usent mye comunement pur le hastyfe payement a fere escryt ne taillie.
And the Latin super unguem was a legal term used in Scotland in the early 14th century, as a certain Mr Neilson explained in Notes and Queries of 10 May 1890:
“DOWN ON THE NAIL.”—This is a well-known half-slang phrase used for a cash payment. Of its history I cannot speak; but I confess to feeling startled when I found it, as it seems to me, in a parliamentary deed of King Robert the Bruce. By indenture dated July 15, 1326 (‘Scots Acts,’ i. 476), a tenth-penny was covenanted for, payable to the king. On his part he agreed not to exact certain prises and carriages unless he was passing through the realm, after the custom of his predecessor, Alexander III., “for which prises and carriages full payment should be made super unguem.” (The words are, “Pro quibus prisis et cariagiis plena fiat solucio super unguem.”) I am aware of the classical use of the phrase “in unguem,” or “ad unguem,” signifying “to a nicety,” but it does not seem to apply here. At the same time the corresponding French phrase, “payer rubis sur l’ongle,” may make this doubtful. Just below the passage cited occurs another in which payment is to be made “in manu.” Both in my opinion refer to ready money, and I do not hesitate to translate “super unguem” “down on the nail.” Hitherto I have supposed the nail to be a figure of speech for the counter on which the coin was told. Apparently this is erroneous, as it is clearly the finger-nail which is referred to. I would like to hear of other early instances of “down on the nail.”
The phrase on the nail probably originated in the custom of wet bargaining, in which the parties drink together. This would account for the shift, in French, from faire, or boire, rubis sur l’ongle (to drink to the very last drop) to payer rubis sur l’ongle (to pay exactly what is due).
The custom of wet bargaining is mentioned, for example, in the accounts of the bailiff of Cuxham, in Oxfordshire, about the year 1330. They show that his expenses incurred on a journey to London to purchase certain millstones included “the luck or bargain penny 1d., and 5 gallons of wine for drinks 2s. 1d.”, so that the bailiff seems not only to have paid the luck penny, but to have provided the beverage, during the consumption of which the bargain was negotiated and completed.
(The luck penny was a small sum of money which, by tradition, is returned by the seller to the buyer.)
1: It has been said that the Latin ad unguem is the origin of payer sur le ungle, albeit with a shift in sense. The Latin ad, or in, unguem meant to a nicety, exactly, perfectly. For example, in Ars Poetica, the Roman poet Horace (65-8 BC) wrote “carmen decies castigare ad unguem”, literally “to chastise (= to correct) a poem ten times by the nail”, that is, to perfection. It was apparently an expression borrowed from sculptors, who, in modelling, gave the finishing touch with the nail, or from joiners, who tested the accuracy of joints in wood by the nail.
This theory seems totally unlikely. In the first place, in this context, Latin ad unguem does not translate as on the nail but as with, or by, the nail. And, not only is the Anglo-Norman form recorded in 1291 sur le ungle, but the Latin form recorded in the 1326 Scots Acts is super unguem, not ad unguem. Additionally, in the above-mentioned bilingual dictionary by Randle Cotgrave, the form sur l’ongle has a totally different meaning from that of à l’ongle (= ad unguem), which is:
Conduire à l’ongle. To finish, or bring vnto perfection; to leaue no iot [= jot] vndone of.
The expression à l’ongle also meant scrupulously, meticulously, in minute detail.
2: Several attempts have been made to associate the phrase on the nail with a stand in the shape of a post or bollard, called a nail, on which payment was made at certain stock exchanges. But the expression existed before exchanges were created. An example of these attempts is found at About Bristol: The Nails:
The four Nails stand on the pavement outside the Corn Exchange in Corn Street. These round-topped pedestals were used by merchants when closing a sale. Money was placed on the surface of a Nail, signifying the bargain had been struck; hence the expression ‘Paying on the nail.’