The Design of a Marking Rule

By The Metric Maven


I’ve discussed the design of rulers a few times before. I’ve always been amazed at the number of options which have been used to define their divisions, and label their values. The website BoingBoing introduced me to another option for ruler design-–stenciled holes. The Incra website has a  millimeter metric-only ruler with stenciled holes that allow a person to mark distances with great precision. I could not help but purchase a 300 mm version to see how well it works. To the left is the label which boasts that this rule is a new 300 mm long metric, albeit 300 MM on the label.

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The first thing one notices is that the numerical labels for the holes and slots bounce up and down. I suspect this was done with the intention that separating the numbers spatially, would make it easier to distinguish them. In my view, it tends to be a bit of a distraction, but this type of separation has been used on other rulers and seems workable. This is a minor concern as Incra offers millimeter-only rules of this type in the US, which is of great utility when other options are limited.

The rules are flexible enough to conform to many objects and allow for accurate marking.They are also essentially stencils, and without pressure, do not return to a flat planar state under their own weight when placed on a flat surface. They are not really designed for use as an everyday ruler, but are for woodworking projects and other designs which might need a conforming rule with precision measure.

Below is a close-up of the left end of the rule:

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Incra has a lot of marking options on these rules. They have openings that will just accommodate a 0.5 mm Pentel mechanical pencil lead. One must extend the pencil lead far enough out to protrude through the hole or slot as the outer lead guide is too large to fit. The zero marking spot on the left hand side of the rule for both the line and single dot markings is cut in half to maintain the best accuracy possible. In the case of the dots at the center they start with half and are stepped in case you want even more accuracy and option.

A video shows how certain versions of their rulers allow you to mark dots and lines with ease, but they tout their inch-length versions and only casually mention that metric versions are available. If a person misguidedly insists they must have both a US inch and millimeter scale, the best version in my view is the 10″ decimal/mm marking ruler. The top scale is millimeters which is a clue that metric is the preferred scale for measure. Below is the inch scale which is marked in tenths of an inch with 1/20″ openings between. Recall that a millimeter is about 1/25″ and is the most precise measurement increment on the scale.

Related essays:

The Design of Everyday Rulers

Stickin’ it to Yardsticks

The American “Metric Ruler”

America’s Fractional Mind


The Metric Maven has published a book titled The Dimensions of The Cosmos. It examines the basic quantities of the world from yocto to Yotta with a mixture of scientific anecdotes and may be purchased here.


US Scientists Not Using The Metric System

By The Metric Maven

Bulldog Edition

A Vox article, American energy use, in one diagram, shows that US Scientists using the metric system are Mormons Making Coffee,  without adding any coffee. A diagram is presented for 2016 energy use in the United States:

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The units used are in quadrillion BTUs. BTUs are not even a well defined unit. It is stated that a BTU is about 1055 joules. So, a quadrillion BTUs is about 1055 Petajoules. The chart has this run-down for energy consumed in the US:

Because the energy values are BTUs nested inside of a name called a Quad, this is even worse than using Olde English prefixes. The actual energy unit is hidden in a nickname. Clearly it could be worse, the different energy sources could be a mixture of KWh, “metric tons” of coal, and so on. The Quad is simply an Argot, used by insiders to make what they do less transparent. See my essay, John and the Argot-nauts. The author of the article tries to put a Quad in perspective by offering this list of Quad equivalents.

A “quad” is one quadrillion (a thousand trillion) BTUs. Here, according to Wikipedia, are a few things equivalent to a quad:

8,007,000,000 gallons (US) of gasoline
293,071,000,000 kilowatt-hours (kWh)
36,000,000 metric tons of coal
970,434,000,000 cubic feet of natural gas
25,200,000 metric tons of oil

So a quad is a lot of energy. The US consumed 97.3 quads in 2016, an amount that has stayed roughly steady (within a quad or so) since 2000.

This list of units seems to ask a reader to add apples, oranges, grapes, strawberries, blueberries and then compare the sum to bananas. In the metric system we choose but one fruit for comparison. In this case the choice of Petajoules will produce integer comparison values for the smallest and the largest values.

If we use Naughtin’s Laws to rewrite this list in metric we obtain:

Total Energy  102 652 Petajoules (without rounding)

The data is presented in all integers and the numbers are easily comparable.  Solar and Geothermal do not contribute much of the total, but Natural Gas, Coal, and Petroleum do. Even in the US, a joule is almost certainly a more recognizable energy unit than a Quad, as is the metric prefix modifier Peta- (Petabytes of data storage). The units are suppressed in the original diagram, so we could indicate all values are in Petajoules (PJ) and simplify the table further:

The article notes that most people immediately notice the amount of wasted energy, which is about two thirds according to the article, or about  68 435 Petajoules.
The same diagram from 1970 is presented, also in Quads:

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It shows that in 1970 we generated about 71 213 Petajoules of energy and wasted 32 178 Petajoules. Wow, we now  officially waste about as much energy as we generated in 1970!

In 1950 the total generated energy was 32 810 Petajoules, of which about half was

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The larger point is that scientists at LLNL continue to express energy values the same way they did in 1950. There is also a strange implicit assumption that if the values are presented in pre-metric units, that somehow they will be understood better by the public. This is probably just a rationalization for using internal argot to express these values. One can only speculate why there has never been a change. One thing that is certain, is there has been a significant change in the complexity of our energy generation in the US since the 1950s. The 1950 diagram has four energy inputs, today we have nine. To best understand this information, one should examine how it has been presented in the past and consider a simpler, more intuitive way of expressing this data. The metric system would be a good start, and perhaps reading Edward Tufte might be the next step for government scientists to investigate better ways to express this data, assuming they actually want to, not just for public understanding, but for scientists, engineers and others.

Thanks to Peter Goodyear for bringing this article to my attention.

Related Articles:

Joule in The Crown

John and The Argot-Nauts

The Metric Maven has published a book titled The Dimensions of The Cosmos. It examines the basic quantities of the world from yocto to Yotta with a mixture of scientific anecdotes and may be purchased here.