Right! so this post is about sewing needles, where gauge/diameter are slightly less important than in other types of needle, such as medical needles or knitting needles. There's of reasonable amount of wiggle room in crafting a sewing needle, a very ancient technology that can really be made any old way (it doesn't even need to have an eye - it can just be a poky thorn or animal quill that pokes thread through holes.) And the technological innovation of the metal sewing needle being made from drawn wire and the points ground on a grindstone is supported because we know that's how they did it and because that's the easiest way to to make long thin pieces of metal, so needle size mapping to wire size (and a higher number being number of draws through a plate) makes sense.
A historical forerunner of knitting, nalbinding, involves a single bone needle that looks like this, which is a tool that a reasonable competent handcrafter can make from bone.
The modern practice of fast knitting, however, requires at least a pair needles whose diameters exactly match, and for a lot of knitting work, require a set of needles that exactly match.
Sewing needles are tremendously low-tech tech. As I said, the eye is optional. It is not-impossible to make a bone, wood, quill or ivory needle with very little technology, simply by whittling. The introduction of metal wire-drawing techniques made them easier and better-quality, but you don't need to start with fine metalcraft to sew. (although sewing does FEEL like that. If You Wish To Make An Apple Pie From Scratch Sew A Single Flipping Button You Must First Invent the Universe.)
Knitting needles are pickier in their production than sewing needles. It is annoying and difficult to make four perfectly matching bastards. Also, since knitting makes its own fabric as it goes, it's very useful to have a fixed idea of the diameter of the needles, because that determines the properties of the resulting fabric.
So knitting needle popularity and knitted textile volumes are strongly (but not universally!) linked to the development of drawn-wire metal manufacturing, and the rises in popularity of knitted textiles follow the rise of drawn-wire metal manufacturing. European depictions of Knitting Madonnas show Mary knitting in the round on long metal double-points.
(also, for the record: knitting needles used to be called "pins," in English, which made a bit of sense because, like pins, they don't have eyes. But they also make stitches (like needles). At any rate, English now calls them "needles.")
So why aren't knitting needles - which you'd think are more closely linked to wire gauge - numbered "backwards" (higher number -> smaller needle) like sewing needles are?
Well, regrettably, they used to be - and that's how you'll find needle sizes described in (for example) early 20th century European knitting patterns! the oldest methodologies of knitting terminology corresponded in some ways to "draws through a plate", though it's hard to find out more about that (a historian who cares could do that) because standardised wire gauges weren't common, knitting patterns were secretive, the textiles themselves haven't survived, and people didn't think it was very important. Various countries and artisans used different numbers to describe wire and needles, and there were no consistent gauges for any.
That's why, today, a serious knitter will have a helpful tool to measure needles, detect what size they are, convert between USA and metric needles sizes, and also helpfully measure the gauge of the knitted material in cm or inches to compare against the expected fabric gauge in the pattern. To measure your needle, you pass it through the hole and see which one it matches! Here's a knitter's gauge:
You'll notice that a modern knitter's gauge recapitulates two tools from further up the thread (ha) - it resembles the wire draw plate, used for making wire, as well as the more engineering-looking wire gauge! This is because, again, it's one of the more efficient ways to measure this kind of material item. But you'll note a few other things. One is that there are quite weird numbers on one side. The hole at the bottom, labelled "9.00 mm" on one side, clearly refers to the current standard 9mm knitting needle. In the US, this needle is called a size 13... and in some mysterious measurement called GWR, it's 00.
This harkens back to when knitting needles were connected to wire-drawing and the numbers ran "backwards". I don't know precisely what GWR stands for, but it's known to be connected to that, and thus some kind of "gauge wire reference."
A blogger who has looked at old knitting gauges connected Chamber's Bell Gauge with a knitting pattern, which begins: Take steel pins No. 13, Chambers' bell gauge...
Here's Chamber's Bell Gauge for sizing knitting needles. This gauge was created in the UK in 1847 and became almost the knitting standard - and the numbers go backwards. You can see that a size-1 knitting needle is the biggest, and indicates the size of the wire used to start making knitting needles! and the more "passes" make a smaller needle.
The USA was sort of a Wild West of knitting gauge for a very long time, either using artisanal English gauges (as steel needles tended to come from England anyway, but that's another post) or random individual manufacturer's sizes determined largely by wool size. This is a topic of great interest to people who like historical fashions and designs, and collectors of knitting gauges. An in-depth post below calls gauges, fittingly, "Rosetta Stones". Here's a proprietary measurement system of unclear age - a historian could make a guess - but look at the absolutely fabulous materials the needles could be made from! Bone, steel, applewood, celluloid, and NON-INFLAMMABLE (as celluloid was apparently that much of a problem.) There's a separate scale for your steels. There's a proprietary metric AND the metric system.
Early North American Knitting Needle Gauges Part 1 ā Early Days and the Sizing Challenge ā Webster's Knitting Needle Notions
And what that little card shows is that, at a point that we can only narrow down a little bit, "imperial/USA" knitting needle sizes swung 'round to recapitulate the metric system: bigger needles have more millimetres, and are thus a higher size-number.
But the UK didn't do that. Look at this gauge from part 2 of the post: Early North American Knitting Needle Gauges Part 2 ā The Big Firms in the USA ā Webster's Knitting Needle Notions
It has English sizes going backwards. Because of wire.
By WW2, there was a burst of innovation, from which the USA emerged staggering and blooded, with a single unified knitting-needle size, agreed-upon as a shared industry standard by needle manufacturers. This happened overnight and possibly as a result of a drinking session.
With the USA having pinned (ha) a measuring system down, and Metric ticking along in blissful and inarguable perfection, the Old English measurement, or GWR, based on the "backwards" wire scale, started disappearing.
Today, we tend to measure knitting needles as either Metric or USA, and patterns note both:
But if you're interested in historical knitting patterns, which use either "old English sizes" or an equivalent, those go backwards - and link directly to wire gauge.
This is part of the underpinning tradition of knitting being a direct conversation across the elders of human history (if you wish to knit a mitten, you must first reconcile the generations) as well as a pitched long-distance psychic battle with the pattern designer.
I hope this helps nothing, and confuses you more. Kiss!
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