Tuesday, 27 November 2018

Mixed imperial/metric units

Pub Curmudgeon on yesterday's post:

As fuel is actually sold in litres, it might make sense to use miles per litre, but mpg is the established figure, and creating a hybrid unit combining Imperial and metric units would annoy a lot of people on both sides of the debate.

I'm not sure it would. There are already examples of mixed units, my favourite being tyre sizes:

HOW TO READ YOUR TYRE SIZE
Example: 215/60R15

215 is the width of the tyre in millimetres.
60 is the aspect ratio or tyre profile.
R means it is radial construction.
15 is the diameter of the wheel rim in inches.


Yup, they mix metric, imperial and a ratio - 60 = 60% of 215mm = 129mm = the distance between the edge of the rim and the tread, or possibly shoulder, of the tyre.

15 comments:

Lola said...

I love that as well. And then there's timber and other materials sold in metric equivalent of imperial - 32 mm. Or 52 mm for exaple

Edward Spalton said...

I was in the animal feed and agricultural supply business which went metric many years ago. Whilst I was familiar with metric units, I never really got the instinctive feel for combined measurements grams per litre rather than pounds per gallon etc - a.though I knew full well what a gram and a litre were.

So, passing a seed and feed store recently, I went to see how they were doing things now. Labels on packages of herbage seed
mixtures gave the sowing rate in kilograms per ACRE which I found reassuring.

Mark Wadsworth said...

L, yes that sort of thing.

Ed, kg per acre, lovely!

Lola said...

And there are those very important units, like a 'tad' or a 'smidge'...

Dinero said...

And there is the wood planks with dimensions in inches and priced by the metre.
And Metric socket sets with a 3/8 inch driver.

DCBain said...

You can't be too careful. In my son's workshop we always ask whether it's a metric or imperial smidge.

And as I told AKH the other day - that captcha is a pain in the neck!

Edward Spalton said...

Not strictly a metric/imperial issue,
In the early Sixties I was s pupil at a firm of corn merchants in Banbury and we bought cakes from la local bakery for our stand at the Oxfordshire show which had to be collected very early in the morning.

The Baker was half amused/half appalled at an insignificant incident which, in his opinion , showed the defects of modern education.
Their delivery men often had a lad as an assistant.

One van man had asked the lad to count how many loaves they had left. The boy came back and said there were “lots”.
“I want to know how many” said the driver. Go and check.
The boy came back after a while and said
“ I .weren’t far wrong. We got best part of a tidy few”

Mind you, my first day in the corn merchant’s office had started with the Manager, a man from a very austere religious sect, passing me a weighbridge ticket 5 tons 2 hundredweight 3 quarters and 1 stone . “There you are” he said “ twenty five pounds twelve shillings and six pence per ton. What does it come to?” When I asked for a piece of paper to work it out. “Lord love you, lad. What have they been teaching you all these years” . I have never forgotten it with everybody watching the fun in that Dickensian office with high sloping desk and office stools. It was a very happy two years where I got to do most jobs in the business.

Lola said...

ES. That's like the stories about sending the new lad off to the stores to get a rubber hammer and a dozen glass nails..

There's another one - a dozen. To amuse myself I occasionally ask for a metric dozen (i.e. ten) of something - it drives my wife and children mad. Double win then.

Lola said...

Whatabout BSP/BSW thread sizes? so you have a tap size 1/16 inch and the tapping drill size is 6.4 mm.

Mark Wadsworth said...

Thanks all. Keep them coming.

Ed, can you tell us how to work it out? It would take me twenty minutes.

Bayard said...

Lola, it's worse than that. Most of the building industry uses the metric inch of 25mm. This is fine for small measurements, but an 8 by 4 sheet of plasterboard is actually 1200 by 2400mm, 20mm short in one dimension and 40mm short in the other. Just to make things worse, plywood sheets are still the full 48 imperial inches by 96.

Mark Wadsworth said...

Re metric inches, the Europeans still refer to 500g as a "pound", especially when referring to food.

Mark Wadsworth said...

Ed, was the answer "about £130" good enough or down to the last ha'penny?

Edward Spalton said...

Good enough for me!

Edward Spalton said...

I had another go and came up with £131 -16- 8 ( approx)
But I did use my calculator and decimals of a pound and rounded the final figure out slightly for bits of it.

We used to have books called Ready Reckoners from which you copied figures from different columns and added them up.

My father was rather more modern. He had a Swedish calculator called an Odhner . You entered the price wi decimals of a pound and the weights as decimals of a ton and turned the handle.. He was sometimes a penny or two different from the Ready Reckoner.