Category Archives: Metric Reform

Don’t Take Ye Olde English Wooden Nickels

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Photo by the Author

By The Metric Maven

Bulldog Edition

I’ve always liked wood. My Grandfather was a carpenter, my father also knows how to work with wood. I, alas, do not. My father can generally recognize different woods, I haven’t a clue. The variety of woods that exist is astonishing. I recall reading about how the English carpenter and clockmaker John Harrison (1693-1776), used a wood called Lignum vitae, to construct wooden clocks. This wood actually has the property that is is self-lubricating, which allowed Harrison to make bearings and gears of it for his pendulum clocks. It is also one of the hardest woods in nature. In my youth I marveled at the Balsa wood rubber band driven airplanes available at the local dime store. I also have an interest in photographing wooden grave markers. An image of one of these “tombstones” I photographed is shown in the photo above.

I thought back on all this when paging through an old book called Science in Everyday Things by Engineer William C. Vergara and published in 1958. The book is a list of questions with answers, and one of them is: “Does all wood float?” What I assume he means is that given a solid cube of wood, will it float in water? When Vergara offers his answer, he informs his readers that the density of water is 62.5 pounds per cubic foot. Any wood with a density above this will sink and any below this will float. What struck me was the contrived and arbitrary nature of this value. It reminds me of the freezing point of water being defined as 32 degrees, an arbitrary magic number to be remembered on the Fahrenheit scale, because of poor measurement planning.

What struck me even more was that I was still going along with all the people who use kilograms per meter cubed. In my view, this is a vestigial Ye Olde English use of metric, which should be diminished. Density is the mass of an object divided by its volume. The everyday common volume unit allowed in metric is the liter, and a liter of water is essentially a kilogram. This means that a liter of water has a density which may be written as 1000 grams/liter. Both grams and liters are familiar units in the everyday world of an average person in a metric country. If a wood’s density is below 1000 grams/liter it will float, if it is above 1000 grams/liter it will sink. This is a nice Naughtin’s Laws friendly way to express water’s density, and it does not involve recalling a number like 62.5 pounds per cubic foot. This method essentially relates the specific gravities of the woods in an elegant fashion. It allows one to rationally list the densities of various woods in a way which one can immediately realize if they would float or not:

Wood             Density (g/L)

Balsa                           96
Yellow Pine                650
Maple                         704
Hickory                       816
Water Gum Tree      1000         (Density of water)
Black Ironwood        1040
Poison Ash              1104
Arapoca                   1200
Lignum Vitea           1229
Qeubracho              1393

Balsa is the lightest of the woods and a cube of it will clearly float in water. Yellow Pine, Maple and Hickory will also all float in water. Yellow pine was chosen for use in the caissons that were used to construct the Brooklyn Bridge.[1] Southern Yellow Pine was chosen for it’s ability to withstand large pressure and for the considerable amount of resin it contains. This makes it very resistant to rotting. Wood from the aptly named Water Gum Tree has neutral buoyancy, that is, it has essentially the same density as water and is compelled to neither float nor sink in it. A block of Water Gum Tree wood is like a helium balloon which floats at a stable position, neither rising nor falling to the floor. The word Quebracho means “Ax Breaker.” Given its high density, this name seems appropriate.

In his last sentence Vergara states: “Since wood weighing more than 62.5 pounds per cubic foot will sink, it can be seen that many  kinds of woods cannot possibly float.”

This is true for a single monolithic block of wood, but all these woods can be used to make vessels which will float, they only need to displace enough water to do so. The Civil Engineering students at Iowa State University each year create a concrete canoe. The density of concrete? It’s 2400 grams per liter. But concrete is not nearly as dense as steel which is about 8000 grams per liter. The hollow interior of a canoe or ship decreases the overall density of the ship enough to bring it well below the 1000 grams/liter threshold, which in turn allows it to float. Allowing for shaping, all wood will float.

I very much encourage the use of grams/liter for expressing density. I completely discourage the use of the cgs leftover, grams/cubic centimeter. In the case of steel its density is 8.05 g/cc. I also mostly tend to discourage the use of kilograms per cubic meter, as the units are out of the range of everyday measurement experience. It is, however,  very easy to convert from kg/m3 to g/L. For instance, the density of steel is 8000 kg/m3 which is 8000 g/L. The conversion factor is one. The numerical values are the same, just change the units. It’s just that easy, as the metric system is, and should be, when it’s employed in an articulate manner. People who insist on using Ye Olde English units like pounds per cubic foot—are just dense.

[1] The Great Bridge, David McCullough, Simon and Schuster, New York pg. 174-175.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

Joule in the Crown

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By The Metric Maven

The creators of the television series Futurama had a question about money in the future. Would there be any? After deciding there probably would be, they speculated about what form the currency might take. An early suggestion for a currency basis was the joule, but in the end they opted for the dollar. The joule seemed like a much better idea to me, what is more important to the “modern” world than energy? Energy has made life luxuriant when compared with the life our forefathers (and foremothers) experienced. The joule is the unit of energy in the metric system and would be universally recognized—well except in one country.

Recently a fellow from the local energy company knocked on my door and announced he needed to work on the gas meter. Apparently in the mid-1990’s a wireless reader was installed so it could be read remotely. The battery was at the end of its life and so it was to be replaced. I watched as the technician unscrewed the existing meter module, which has its units in cubic feet. He then replaced it with an identical module, which in the year 2014 still reads out in cubic feet of gas.

My utility company sends me a bill for energy usage each month. The word energy is even in their corporate name. Below is a scan of a recent bill’s comparison information section:

The gas and electric energy usage is offered in Kwh per month and in therms respectively. The Kwh stands for kilowatt-hours. A watt is a joule per second, so multiplying a value in watts by hours is pigfish talk. The recognized unit of time in SI is the second. For this bill, the first energy value given is 928 Kwh for the electrical energy used, but energy is internationally described in joules. When all the conversions are done, the electrical energy used for the month in SI is 3341 megajoules.

The natural gas usage is assumed to be in Therms. So what is a therm?  Well, in the US, it’s 100 000 BTU, and BTU are British Thermal Units, but not the British Thermal units used by the British, those are a bit different. These are American British Thermal Units—you know—the patriotic kind. Gas meters don’t directly measure the energy delivered, but instead the volume of gas delivered. According to Wikipedia:

Since (Natural Gas) meters measure volume and not energy content, a therm factor is used by (Natural) gas companies to convert the volume of gas used to its heat equivalent, and thus calculate the actual energy use. The therm factor is usually in the units therms/CCF. It will vary with the mix of hydrocarbons in the natural gas. Natural gas with a higher than average concentration of ethane, propane or butane will have a higher therm factor. Impurities, such as carbon dioxide or nitrogen, lower the therm factor.

The volume of the gas is calculated as if it was measured at standard temperature and pressure (STP). The heat content of natural gas is solely dependent on the composition of the gas, and is independent of temperature and pressure.

Therms “Explained” for Consumers.  It is noted that 10 therms is a decatherm (Dth) and not a dth as one might expect. This is very “metricy” sounding but clearly not metric. Therms are BTUs  (click to enlarge)

So we have to have a temperature correction, and apply a therm factor which is in therms/CCF. So what is a CCF?  Well, it’s centium cubic feet or 100 cubic feet. So  the first C is the roman numeral C and stands for 100. The second identical C stands for the word cubic and F is for foot. It is sometimes alternatively written as Ccf. MCF is also used for 1000 cubic feet. The M standing for the Roman numeral for 1000 The correction factor is used to calculate the value as if it were at STP (i.e. standard temperature and pressure). Obviously, accurate values for temperature are important in determining accurate values of natural gas usage. I assume that the average daily temperature has some relationship to this required correction factor. It does not have an obvious entry on my bill. Here is what my energy company states:

Therm Multiplier

Gas usage is defined in Therms, a measure of the heat, or energy content of natural gas in a billing period. One Therm equals 100,000 British Thermal Units (Btu). The energy content of gas changes depending on its source, the altitude and temperature at which it is delivered. After your meter measures your usage by volume (in hundreds of cubic feet and appearing on your bill as “Measured Usage”), this volume is multiplied by the Therm Multiplier to determine the units of energy consumed.

Kwh “Explained” for Consumers (click to enlarge)

The multiplier is not broken down any further and does not spell out the individual contributions. Apparently the temperature, altitude, energy content and such are all wrapped into the Therm Multiplier. The comparison section on my bill is strange, as it has natural gas printed on a line above electric as if the top line is gas, and the bottom is electric. What appears to be the case is that the Kwh value (yes I used a capital K) is the amount of electrical energy usage and the therm value is the natural gas energy usage. It is assumed the customer knows and understands this energy demarcation from the Account Summary they’ve presented.

The most straightforward way for both electric and gas usage to be described, would be in terms of energy usage with a single, simple, internationally recognized unit, but they choose not to do this. Instead, the company uses kilowatt-hours and therms. In the case of kilowatt-hours, it is a pigfish unit, which is metaphorically based on metric, but not the actual metric unit for energy, and for therms it is a semi-imperial system unit for energy. Neither of them use the internationally  accepted unit for energy—the joule.

The comparison section of my energy bill could have been written  in a  much, much clearer way, that anyone could understand, using the metric system and gigajoules:

Comparison Information

Metric Comparison (click to enlarge)

When the bill is written this way, one can immediately see the difference in direct energy cost per gigajoule between Electric and Gas. Electricity is 4.85 times more expensive per joule when compared with natural gas. One can assume that the electric usage is essentially for operating appliances and gas is used for heating, just by looking at the energy usage from this year to last. This year was sixteen degrees colder than last year, and the amount of gas usage in gigajoules was different by a factor of 2.6. The previous energy use was lower for the warmer average temperature as one would expect. One also notices what is missing in this table, the comparison cost per gigajoule from the previous year for electric and gas. This would be a very useful way to gauge the change in cost from year to year. The way the energy bill is originally written one could easily confuse the columns. When presented this way, it is clear.

The way the energy usage is presented in the actual/original bill does not allow a consumer to directly compare energy prices—which are offered by an “energy” company. This is because two non-metric proxy units are used, kilowatt-hours and therms, which have a conversion factor between them of approximately 29 (i.e. 1 therm = 29.307 kilowatt-hours).

One cannot be certain about the origins of the format of the bill I received, but I could not help but think about the word confusopoly, which was introduced in Scott Adams’ book The Dilbert Future. According to Wikipedia:

The word is a portmanteau of confusion and monopoly (or rather oligopoly), defining it as “a group of companies with similar products who intentionally confuse customers instead of competing on price”. Examples of industries in which confusopolies exist (according to Adams) include telephone service, insurance, mortgage loans, banking, and financial services.

I would like to add energy companies to the list.

Australian Gas Meter — Photo by Peter Goodyear

Electricity and Gas are pretty basic, both are sold by energy content, so despite the view they are public utilities, one can only wonder if they are not following the confusopoly model when they present bills in Kilowatt-hours and Therms. My rework of my utility bill certainly looks simpler to understand than the one that uses “our traditional measurements.” When the metric system is implemented, people can readily see it’s a system.  When energy is discussed in any context using the metric system, it is always joules, so the energy content on food packages are in kilojoules, as is a person’s energy bill in gigajoules. The metric system allows for a more integrated and systematic understanding of the world by everyone. There will always be those who will try to use metric in a non-transparent manner, but it takes much more effort than when using the potpororri of “traditional” measures currently established in the US. The joule in the crown for energy description is the joule. No matter what energy is under discussion:

Australian Subway napkin with food energy in kilojoules (kJ).  An average person burns (i.e. radiates as heat) about 169 000  kJ per month (169 MJ) (courtesy of Peter Goodyear — click on image to enlarge)
US Subway Napkin with Calories (kilocalories) and grams of fat — The word energy does not appear on the  US napkin (click to enlarge)

Postscript:

On a side note, New Scientist on 2014-01-04 related that since the UK phased out incandescent light bulbs there has been a considerable drop in energy usage. They state:

The average amount of electricity needed annually to light a UK home fell from 720 kilowatt-hours in 1997 to 508 kWh in 2012, a drop of 29 percent.

So  the average energy use by a UK home in 1997 was 2592 megajoules/year  and in 2012 was 1829 megajoules/year

Unfortunately New Scientist can play fast and loose with energy quantities and power values. On 2014-03-08 in an article about using batteries for energy storage from wind power they state on page 20:

Last year California passed legislation requiring the state’s energy companies to create more than 1.3 gigawatts of energy storage between them by 2020.

One could blame this technical faux pas on scientifically illiterate California legislators, but one would expect New Scientist to note this mistake, and possibly comment on it. Energy storage is in joules, the amount of energy flow out of the batteries is watts (joule/second). It is like equating the amount of water behind a dam with the flow rate of water leaving it.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.