Someone here sometime back tried to say that dividing by 2 or doubling a value is easier than X10 or /10 (pro imperial argument). To me, metrics is so much easier. It's literally as easy as moving the decimal point 1 place left or right. No math is involved at all. Just moving a dot. How that is supposed to be harder than doubling/halving eludes me.
The disconnect here is in physical processes. If you have a physical beam that you need to divide in half, that is much easier than dividing that beam into 10 pieces.
Where this is really important is when you are making standard rulers. Your standard measure is approximately the size of a yard or meter; making a ruler that measures inches or centimeters requires dividing that length by 100 or 36.
The metric system isn't really possible until we developed machines that can precisely and accurately divide lengths by arbitrary divisors, which happens only in the late 18th century.
I've seen this example of egg dozens everywhere but i don't get it, egg dozens aren't related to inches. It's just a random number of eggs that happens to be common in packing. Let's say there's any practical reason to have a measurement system bases on 12 egg packs, it falls flat with a 100 nails one...
Eggs is a bad example. Try building a wall and dividing it into 3 sections. The symmetry looks good, but metric makes it a real pain to do that, while base 12 systems make it easier.
Plywood is sold in 8 foot long sheets, or 240cm in metric countries. 200cm would be a more natural metric size, but it is too short to be useful (because plywood is used for things that need to be human height), and so being compatible with the US standard is the compromise construction uses.
Metric is nice in math when you can choose to your values to make things easy. As you get to engineering things get messy just because the nice sizes are not normally even values. Of course all systems suffer from this, 5000 feet in a mile would be a nicer measure but it doesn't fit in with the other things that you want in a system so you compromise. Metric compromised differently and is equally annoying to use for everything.
We should still go metric in the US, consistency is useful.
I'm even further from getting it now. 240cm being a multiple of 12, it can be divided by 2,3,4,6 without precision loss.
Also this logic around inches only works if you happen to need to divide 1 inch. It doesn't work anymore if you need to divide 1.1 inch.
It actually work exactly the same in the metric system if you need to divide 1.2cm
Engineering is math. You start from your constraints, and finish with an acceptable level of imprecision based on your requirements, your tools and your materials. Whatever you do it's never precision work, exactitude only exists on paper.
Plywood in the US is sold in feet. Europeans cut plywood into metric based sheets. Ever try to buy Baltic Birch for wood working? It's actually a different shape than a US sheet of plywood.
Sorry but i fail to see how it's handy.
To stay with thr egg pack unit, it's much easier to say i want 7 eggs rather than a 0.58 of pack (not even sure it's right in egg/inches).
Even this i find it much more convenient in 10s.
A pack of 10 eggs?
You can easily express any content (0.1, 0.2, 0.3...)
Move to the lower unit (move the coma). A quarter of an egg in egg packs? 0.025
Want to move in the egg unit? 0.25
Please prove me wrong but i fail to see how it's easier in 12th, when using a decimal number system.
You're coming at the problem from a metric point of view.
Your instinct is to immediately convert into decimal point numbers, but the strength of the base 12 system is in fractions.
Its very easy to visualize and measure one half, one third, one quarter of something. Humans in their daily life don't come across a situation where they need 0.2 of something. It is much more natural to think of halves and thirds.
Milk (as an example of imperial liquid measure) is another good example. Nobody looks at a gallon of milk and says "boy I wish I could only buy 0.7 of that". The brain is just wired to think of halving and doubling, so we have quarts which are 1/4 gallons, and pints which are 1/2 quarts.
For another example, You never hear about people "0.7x" a recipe. People halve or double a recipe, and imperial measures make that easy to do.
I like the phrase: Imperial units are for humans, SI units are for scientists. This is why I prefer the Fahrenheit temperature scale. The Celsius scale is much more "concrete" in that it has a physical basis for degree 0 and 100, but that doesn't matter for humans. I never have to relate temperature in terms of boiling and freezing water.
In Fahrenheit, 0 is "really cold" and 100 is "really hot". It's arbitrary, but more human friendly.
We really think differently then :D
I definitely don't think about fractions but adapt the unit to my needs. I use fractions to get to
what i need, but the same way i would add, multiply and substract.
I don't relate at all to the Farenheit scale. You can give whatever number, it just doesn't talk to me at all. The Celsius one does though. This is not a matter of a unit being better than another, but what we're used to.
There is another human advantage to Fahrenheit: the degrees are more precise. One degree Fahrenheit is a noticeable but small difference. One degree Celsius is 1.8 degrees Fahrenheit, a much bigger difference. You're practically forced to use half degrees, which works but is ugly.
If the SI people could have broken with the idea that everything must be a strict power of 10, they could have used 200 degrees instead of 100 and had much more human-friendly units.
It's not terribly self-consistent to talk about base 12 (which is not what the old systems in fact used) being strong and then talking about the intuitiveness of 100 Fahrenheit in almost the same breath. (-:
Why not? The use case is different: I have never in my life needed to do quick mental math regarding temperatures. Base 12 is great for quick mental math.
Both the fact that imperial uses base 12 for some units and the fact that Fahrenheit is centered around the human experience of temperature support my larger point that imperial units are more ergonomic.
> Please prove me wrong but i fail to see how it's easier in 12th, when using a decimal number system.
It's not. You have to have a base 12 "decimal" system (dozenal or duodecimal). A half is 0.6, third is 0.4, quarter is 0.3, a sixth is 0.2, an eighth is 0.15, and a twelveth is 0.1.
Eight eggs is 0.8 of a dozen, 0.08 of a gross, or 8 "pg", per-gross, akin to per-centum.
The advantage is that all of those divisions are clearly marked on the ruler, so it’s easy to align your line/cut with it.
In contrast, cutting a 10cm thing in thirds or quarters requires estimating the point 0.33 or 0.25 of the way between marks, which is perceptually harder.
And cutting 3.93701 inches in thirds is somehow easier? Even with 4in, you end up with 1.33 inches. Not very different from 3.33cm is it?
You're just taking arbitrary numbers that are easier to operate with using the imperial system. The metric system is superior because most numbers are easier to operate and measures in fractions of ten.
But that's exactly the point--historically, you wouldn't cut 3.93701 inches. You don't have the precision to do it nor do you have any real reason not to stick with "round" numbers or close enough. Rough carpentry (e.g., framing a house) is often only accurate to a 1/2" or so; very fine furniture might go down to a 1/32rd.
Note that machinists, who do want that sort of precision and can achieve it, mostly work in metric or metric-lite ('mils'=1/1000s of an inch).
I never had issues with cm/mm honestly. And half a milimeter is always a precision hard to reach with home hand tools, so the need to have 0.33 milimeters on a ruler is not there. Tools that reach that precision are in micrometers.
... and only has two prime factors, the same as 10 does, undermining your original point about prime factors.
In 2015, Cadbury stopped selling its creme eggs in packs of six in the U.K. and now sells them in packs of five. Ironically, a subsidiary of a U.S. conglomerate (Cadbury having been taken over in 2010) metricated creme egg packaging.
I'm a metric system person too, leaving with an us imperial system person. I think that the mental model is different. Metric is made to switch units easily, you need precision, just move the comma to get it. The imperial system is used by sticking to the unit and use fractions of it.
