Discussion
I generally use metric measures at work (foundry, so plenty of millimetres, Celsius, kg etc), but then certain things are still imperial (for example, pressure (psi) and speaking to our toolmaker is always in thou, and I cannot readily translate into something I can use......)
I always wondered about thousandths of an inch as it struck me to be emulating the metric system.... must be something somewhere why it went decimalised for thou?
Mike
I always wondered about thousandths of an inch as it struck me to be emulating the metric system.... must be something somewhere why it went decimalised for thou?
Mike
mike_knott said:
I am an engineer, where most things are metric because equations are easier if they are in consistent units. I can't believe how much time must have been spent converting imperial units from tables; and every conversion increases the chances of mistakes.
Outside of work I use °C, metres, millimetres (and occasionally inches and yards, but never centimetres; don't get me started) and miles due to cars and road signs being in miles. I will readily use kilometres when driving abroad. I don't think it makes much difference unless you need to calculate anything at which point the benefits of metric become apparent. With common imperial units of length you have:
Thou, inch, foot, yard & mile (plus several others in specialist areas).
In metric you have the metre, and that's it. Everything else is metres with a prefix in multiples of a thousand.
Likewise, for mass:
Imperial: grain, ounce, pound, stone, hundredweight & ton.
Metric: kilogram (which is a bit odd in itself, but we'll let that go as it is still easier than imperial!).
Most metric units only need conversion factors of 1,000, while most imperial units need numbers which are not easy to remember.
And metric also doesn't use fractions: think about the steps involved in adding six foot eight and five sixteenths to four foot eleven and seven tenths and you'll see what I mean. Even adding seventy five point two centimetres to eleven hundred and thirty eight point six millimetres can be done fairly quickly, and expressed in any metric unit, in the head.
Mike...
I am a child of the post war years and yet will happily work in millimetres, Centigrade (not Celsius), grams and kilos, but what really messed me was trying to switch from p.s.i. and lb.ft. etc,. for stress calculations. I have a copy of Roark's Formulas (sic) for Stress and Strain and it is the Imperial edition. Working out deflections under load in pounds and inches is 'real' whereas the rather esoteric Newtons (or kN because a Newton is an impractically small value), per square metre makes no intuitive sense at all. Remember, because of Imperial/metric misunderstandings the Hubble telescope had to be fitted with corrective lenses!Outside of work I use °C, metres, millimetres (and occasionally inches and yards, but never centimetres; don't get me started) and miles due to cars and road signs being in miles. I will readily use kilometres when driving abroad. I don't think it makes much difference unless you need to calculate anything at which point the benefits of metric become apparent. With common imperial units of length you have:
Thou, inch, foot, yard & mile (plus several others in specialist areas).
In metric you have the metre, and that's it. Everything else is metres with a prefix in multiples of a thousand.
Likewise, for mass:
Imperial: grain, ounce, pound, stone, hundredweight & ton.
Metric: kilogram (which is a bit odd in itself, but we'll let that go as it is still easier than imperial!).
Most metric units only need conversion factors of 1,000, while most imperial units need numbers which are not easy to remember.
And metric also doesn't use fractions: think about the steps involved in adding six foot eight and five sixteenths to four foot eleven and seven tenths and you'll see what I mean. Even adding seventy five point two centimetres to eleven hundred and thirty eight point six millimetres can be done fairly quickly, and expressed in any metric unit, in the head.
Mike...
My particular hobby horse is the modern habit of measuring distance not in miles or kilometres, but in bloody hours. "It's two hours from here..." What? By camel, or aircraft? What's wrong with miles?
motco said:
I am a child of the post war years and yet will happily work in millimetres, Centigrade (not Celsius), grams and kilos, but what really messed me was trying to switch from p.s.i. and lb.ft. etc,. for stress calculations. I have a copy of Roark's Formulas (sic) for Stress and Strain and it is the Imperial edition. Working out deflections under load in pounds and inches is 'real' whereas the rather esoteric Newtons (or kN because a Newton is an impractically small value), per square metre makes no intuitive sense at all. Remember, because of Imperial/metric misunderstandings the Hubble telescope had to be fitted with corrective lenses!
My particular hobby horse is the modern habit of measuring distance not in miles or kilometres, but in bloody hours. "It's two hours from here..." What? By camel, or aircraft? What's wrong with miles?
Or parsecs.My particular hobby horse is the modern habit of measuring distance not in miles or kilometres, but in bloody hours. "It's two hours from here..." What? By camel, or aircraft? What's wrong with miles?
motco said:
My particular hobby horse is the modern habit of measuring distance not in miles or kilometres, but in bloody hours. "It's two hours from here..." What? By camel, or aircraft? What's wrong with miles?
I agree, but would venture one exception - namely leisure craft. When one wishes to reach a particular place, and possibly return that day, then hours are the best unit - because that's what days are measured in. The fact a certain lock is X miles from my marina is immaterial; what matters to me is that it will take me three hours to reach it!Simpo Two said:
motco said:
My particular hobby horse is the modern habit of measuring distance not in miles or kilometres, but in bloody hours. "It's two hours from here..." What? By camel, or aircraft? What's wrong with miles?
I agree, but would venture one exception - namely leisure craft. When one wishes to reach a particular place, and possibly return that day, then hours are the best unit - because that's what days are measured in. The fact a certain lock is X miles from my marina is immaterial; what matters to me is that it will take me three hours to reach it!
Simpo Two said:
1/128ths could work - or in Latin, 'I/I II VIIIths'.
This probably explains why the Romans used 100 instead, because 'C' was easier to write.
Of course, had they known about lower case letters, they could have discovered the speed of light at the same time.
They were busy developing wireless...This probably explains why the Romans used 100 instead, because 'C' was easier to write.
Of course, had they known about lower case letters, they could have discovered the speed of light at the same time.
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