Measurements from the past

I have been reading a 1909 book (in English English) about dynamos which has a long discussion about the thickness of the insulation of the windings, silk, cotton, linseed oil, varnish, asphalt, mica, etc - from a period when plastics were unknown. My question is 'What was a mil?' It looks rather as if it meant the same as a thousandth of an inch, but nowhere does it allow me to be sure.

If it was what we now call a 'thou' - ie 0.001 inches - is/was the same term used in our ex-colonies, I wonder ? And why was the older term abandoned? It would seem to be a better option than thou as it avoids confusion with thou as in the ten commandments.

As an aside, the Anglo-Saxons had a way to avoid the confusion, by having different letters for th in the and th in thing. But we lost the distinction due to influences from Europe ...

Wassail

Tim

I was sure that you were correct, Tim

But it took a visit to Wikipedia to realise the origin of the term

... mil is short for mille

MichaelG.

.

Ref. https://en.m.wikipedia.org/wiki/Thousandth_of_an_inch

Edited By Michael Gilligan on 31/12/2018 18:15:53

Mille. Thanks, Michael. Oh dear, another term from Europe ...

Tim

Well now Tim and Michael, I am agog to know what a 'mille' is or was!

Brian

Mil is still used for 0.001" in that most backward ex-colony across the Atlantic. Mille, French for 10^3, but used as 10^-3, as in mm, mg, etc.

Edited By Kiwi Bloke 1 on 31/12/2018 18:53:01

Mille was the Roman term for one thousand - hence the M in their letters for numbers system. I expect they got the term from the Greeks or the Etruscans. It survives in English as the basis for words like Millipede and Millenium, and in almost its Roman form in several languages (Italian, Spanish, Romanian, Welsh, etc) and as a multiple in the Metric System.

Cheers, Tim

Interesting that Wikipedia says

A derived unit of length in an inch-based system of units. Equal to ​¹⁄₁₀₀₀ of an inch, it is normally referred to as a thou /ˈθaʊ/, a thousandth, or (particularly in the United States) a mil.

I recall my father saying that they used the term in the USA (he spent some time there in WW2) but was deprecated in the UK because of confusion with millimetre.

Of course we are Europeans and English and French are in many ways rather close.

While the metric system has now taken over here in the US imperial still rules (can I say that after the trouble George III had with our American colonies? - who knows )

But in my opinion the biggest innovation is not the change of units, but rather the unification of all units into one system - so we no longer have fluid ounces, pipkins, gills, tuns, hogsheads pints etc, but just litres and multiples thereof. Similarly it is grams etc not drachms, troyounce, ounces, pounds quarters, tons, long tons etc

Not so long ago (even in my parents time) every trade or profession had its own favourite units of which few now remain - points for type perhaps, although that is often wrongly applied and carats for gemstones spring to mind.

Edited By Nick Clarke 3 on 31/12/2018 19:40:13

Where a gallon isn't a real gallon it's a mini gallon, at least that's what my Jeep says

Imperial must stick in their throats a bit given all the fuss about the 'British Invasion'.

.

One of my favourites is the 'French' [or Charrière] scale ... which is a measure used for catheters and the like.

How could they [perhaps the ultimate proponents of decimalisation] introduce a scale based on diameter in thirds of a millimetre ?

MichaelG.

It sounds like the French were responsible for Michael G's example but England cannot claim to be blameless in the mixed unit game - remember when decimal coinage was introduced we had a 1/2p coin? At the time I thought of this as an instance of true British stuborness in the face of decimals.

I was once told that American adherance to imperial measurements was a method of protecting their home industry - anyone selling on the American market had to reset their equipment from metric (or British Imperial) standards to suit American expectations.It was easier to ignore the American market.

Perhaps we should not expect too much from a nation that can't even manage to write the date in the correct order

Chas

In what now seems like a previous life, I used to work as a technician for what was then the GPO Post Office Telephones division which later became BT. We had various sets of feeler gauges which were marked as 10 mil, 38 mil or whatever. Before anyone tells me those values didn't exist, I don't actually remember the values, but I do remember "mil". I always understood that they were indeed thous.

I also recall being told that it came from the military. I have no idea as to whether or not that is correct, but we did use to have tools, eg pointed nose (snipe nose?) pliers officially known as Pliers, Wiring, No.2 which were universally known by their original name of "81's". Again I do wonder if the Pliers, Wiring etc description came from the military.

I think it is worth noting that ever since I started work in 1959, resistors, inductors & capacitors always used pre-fixes such as "kil", "meg", "milli", "micro" etc. to indicate a suitable value multiplier, with "milli" in particular referring to 1/1000 (ie 10 to the -3). Which brings us straight back to the feeler gauges being so many "mil", ie so many thous.

Peter G. Shaw

Probably from when the French legally defined PI=3

And then there is the circular mil, which is a unit of area used as a measurement of wire diameter. IIRC one circular mil is the cross sectional area of a wire 1/1000 of an inch in diameter, and thus is equivalent to 5.07 * 10e-4 mm2. Beware of the confusion abounding when the author means circ mil but writes mil

Happy New Year!

...and units for the future? The minimum possible length is the Planck length, so speeds can be expressed as multiples of it. The maximum possible speed is the speed of light, so speeds can be expressed as fractions of light-speed. The unit of time is then the time taken for light to travel one Planck length. Useful in physics, but far too many zeroes to deal with, for everyday use.

Don't worry folks, after Brexit, there may be sympathy for rods, poles and perches again. As long as beer still comes in pints, it's OK...

.

... and the mil of elevation, which is a mililradian

MichaelG.

Up to the start of WWII, electrical capacity was expressed in 'jars',after the Leyden variety. That was not long after spark transmitters ceased to be installed in new ships.

So we had better add the military MIL. which in a full circle gives 6400 MILS, 1 MIL subtends 1 meter at 1000 meters so it is easy to use for artillery corrections annd for spotters to give corrections for fall of shot. To add that you can get Theodoilites scaled in MILS.

Clive

I tale I remember from many years ago relates to a friend of mine who was measuring something with another mutual caving friend.
Essentially they got different measurements, John was using an old vernier and Norman a micrometer.
On further investigation, the vernier was marked in both metric and imperial, but didn't have 25.4mm to the inch.

One of them checked up on the part number with Moore and Wright, where it transpired that the vernier was a pre-war export model (Belgium from memory) from before they had accepted the "industrial inch" as 25.4mm
Each continental metric market had its own specific vernier model, relating to how they defined their "inch" locally, the metre having already been accepted as a common unified measurement.

I guess be careful with old, (especially imported, or pre-1930s) measuring kit.

From the above link;

In 1930, the British Standards Institution adopted an inch of exactly 25.4 mm. The American Standards Association followed suit in 1933. By 1935, industry in 16 countries had adopted the "industrial inch" as it came to be known

Bill

Edited By peak4 on 31/12/2018 22:40:48

I worked for an engineering company and one of the inspectors was German. We asked him how many thou's were in an inch and his reply was there must be hundreds!