Learn English – the origin of “in a jiffy”

What is the origin of "in a jiffy"?

Etymology online Dictionary says origin unknown but speculates that it was slang (cant) for lightning and dates it as 1785.

Wikipedia agrees but adds that the American physical chemist, Gilbert Newton Lewis (1875–1946) was the first to actually specify how long a jiffy was, a mere 33.3564 picoseconds. Nowadays a jiffy is the delay interval between one computer animation frame and another, particularly in Autodesk Animator, it being defined as 1/100th-of-a-second (10 ms) jiffies (if I've understood that part correctly).

Grammarphobia mentions the OED entry and goes on to say

The Chambers Dictionary of Etymology speculates that the word might
have been “spontaneously coined” by Raspe, a German librarian, writer,
and scientist.

The earliest recorded use of "in a jiffy" I found is dated 1780 from The Town and Country Magazine, Or Universal Repository of Knowledge, Instruction and Entertainment.

This was pure luck, a serendipitous moment, I had been looking for variations of the idiom twist someone around one's finger when I saw "in a jiffy" being used in conjunction with the metaphor. In fact, if one types "jiffy" in the search box, Google informs "there are no results for jiffy in this book" but I found two instances!

Most of the limbs of law do everything in a jiffy; but ask what they mean, and they would be as much puzzled, as if you required of them the explanation of a common act of parliament. If such gibberish were confined to hackney clerks of twelve shillings a week, we should not notice it, as we should scarce ever have our ears grated with it; but the misfortune is, by degrees it has found its way into more polite assemblies, and a lady of taste was heard to say the other evening at the Pantheon, that she could turn Sir William B_____ round her finger in a jiffy.
If people of sense or common understanding, would reflect one moment
on the folly of using words and phrases they could not explain, they
would certainly explode them, and shun those who used them, as being afflicted with a verbal contagion, …

As fascinating this felicitous episode may be, it didn't explain the origins of this expression.

jeffy

A spelling variation in Francis Grose's book, Classical Dictionary of the Vulgar Tongue (1796)

It will be done in a jeffy: it will be done in a short space of time,
in an instant.

^{updated: 17 December 2017}

in a jiffey

In The Newcastle Jester; being a choice collection of Entertaining Jests, Humourous Tales, Droll Stories, Lively Puns, &c (1804) We have:

Two Irishmen fishing one day in the Liffey,
Which runs close by Dublin's great city so fine,
A smart show'r of rain falling, Pat, in a jiffey,
Crept under the arch of Queen's-bridge with his line.
"Arrah, that's not the way to accomplish your wishes,"
Cries Dermot,—" there devil a bite will you get."
"Ogh! bother," says Pat, "don't you know that the fishes
Will creep under here, to keep out of the wet!"

There are other instances where the alliteration Liffey (the river that flows across Dublin; Ireland) and jiffey are repeated. In a song entitled, Master Rooney of Ballinafad's Travels and Voyage, dated 1807, we have the following example:

giffy

Another spelling variant was giffy I found several instances of this word in Google books but none told me their origins.

• 1822 (London); "he saw Mary walking along the road we a strange man, […] that Mary fell in a fit and the man attempted first to help her, but that William sent him flying over the hedge in a giffy, and threatened Mary,…"
• 1833 (Middlebury College, Vermont); "Done, and O the philosophers scales effected nothing half so wonderful! The seven were raised in a giffy, and we verily concluded it would take five more to restore the equilibrium."
• 1833 (New York); Giffy, a rapid and brief space of time.
• 1866 (Lincolnshire); Giffy.—Immediately. Ex. I'll be with you in a giffy. Giffling.—Moving about impatiently

in a jiffing

The expression, in a jiffing was apparently well-known in the USA. In Dictionary of Americanisms By John Russell Bartlett (1859). The term To rights is defined as Directly; soon and by the expression in a jiffing.

In a jiffing was also used by Dickens in his All the Year Round, Volumes 15-16 dated 1866.

jiffle

I found the following excerpt in The Dictionary of English Etymology E – P, Volume 2 By Hensleigh Wedgwood (1862)

It appears that a jif and jiffy is a shortening of jiffle or is it the other way round? Is jiffle a diminutive of jiff? Which is older?

^{Hal.— stands for Halliwell's Dict. of Archaic and Provincial Words}

jeffey

Lastly, I found yet another spelling variant in A Dictionary of Slang and Colloquial English (…) Slang and its Analogues By John S. Farmer and W.E. Henley, printed in London 1905

Curiously, the authors establish its date three years before Francis Grose's dictionary was published but, yet again, fail to explain its origins.

Which language or dialect does jiffy derive from? Was it originally a nickname? Was it really Cant for lightning? Will we ever know the truth?