One area I have always found interesting is the standardization of measurements; that locked in a vault somewhere there was some piece of metal–probably some rare alloy in a vacuum or at some specific temperature–that was exactly twelve inches long or weighed precisely one pound, and these were the standard foot and pound by which all others were measured (and for once that phrase would not be a cliche). I also find the fact that the definitions for these measurements have changed over the years as science and technology evolve to higher levels of precision (What?! A yard isn’t a yard anymore?). I stumbled upon an article titled This Kilogram Has a Weight Problem and followed it up with this Wikipedia entry and came away with some interesting facts, in a dorky ‘umm… sounds great, gotta go’ kind of way:

Originally, the kilogram was defined as equal to the mass of one cubic decimeter, or liter, or water. In 1799, this was refined from water at 0° to 4°—the temperature where water reaches its most stable and maximum density.

In 1879, the International Prototype Kilogram was constructed, a cylinder of 90% platinum and 10% iridium. It was ratified as the kilogram in 1889…and remains so to this day. The IPK and six of its siblings reside under bell jars inside a vault that requires three keys and is maintained in an underground facility outside Paris, France by the International Bureau of Weights and Measures. The kilogram is the only unit that is still defined by an actual, physical artifact.

Copies of the IPK have been produced and distributed around the world to other nations as their version of the “standard”. The United States owns two of these, named K4 and K20, and they come from a batch of 40 delivered in 1884. The IPK replicas are compared to the original every 50 or so years…and many of the copies have actually gained mass, albeit a near-infinitesimal amount, over the years. Or the original IPK has lost mass, but since it is the standard, it doesn’t lose mass—it is always correct.

Work has been ongoing for many years to redefine the kilogram in terms of fundamental concepts of nature, and not in relation to a physical piece of metal locked in a safe. This new definitions include using the number of carbon-12 atoms, a sphere of silicon, or a new-fangled machine called a watt balance.

The Meter

According to Wikipedia, in 1791 the meter was defined as one ten-milionth of the length of a meridian from the Equator to the North Pole (that happened to pass through Paris). In 1889, the meter was defined much like the IPK—the distance between two marks on a bar made of platinum and iridium, measured at the melting point of ice.

This was refined in 1927 to:

the distance, at 0°C, between the axes of the two central lines marked on the prototype bar of platinum-iridium, this bar being subject to one standard atmosphere of pressure and supported on two cylinders of at least one centimetre diameter, symmetrically placed in the same horizontal plane at a distance of 571 millimetres from each other

Not 570 millimeters. 571. In 1960 the meter definition was changed and became:

equal to 1,650,763.73 wavelengths of the orange-red emission line in the electromagnetic spectrum of the krypton-86 atom in a vacuum.

The current definition of the meter was determined in 1983:

The metre is the length of the path travelled by light in vacuum during a time interval of 1⁄299 792 458 of a second.

The Second

Our current definition of the meter now begs the question; how long is one second? Again, Wikipedia says that the second first became measurable in 1670 with the development of a seconds pendulum for pendulum clocks [geeky sidenote: early proposed definitions of the meter related to the length of this pendulum].

In 1960, the definition of the second became:

the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.

Don’t ask me what ephemeris time is. With the advent of atomic clocks, the definition changed again in 1967:

the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom.

This had to be “tweaked” in 1977 due to atomic clocks being affected by altitude and in 1997 it was further clarified to include the following:

This definition refers to a cesium atom at rest at a temperature of 0 K.

And that is how a second is defined today. The interesting thing to me in all of this is that as definitions for these measurements have evolved to become more precise, they have also become more esoteric. I like it that an actual, master kilogram exists somewhere.

What About the Foot and the Pound?

I almost forgot. Is there an extremely precise piece of metal that is exactly the mass of one pound or a foot or a yard long locked away somewhere or are they defined in terms of atoms or light? Ironically enough, since July 1959, US units are defined in terms of the metric system:

1 yard = 0.9144 meter

1 pound = 0.45359237 kilogram

As I continue to dust off some of the rust around here, I changed the fonts served up by the stylesheet. Previously, the main typeface used was Lucida Grande and Trebuchet for Mac OS X and Windows users, respectively. For a bit of contrast and because I like old-style figures, I used Georgia for entry headlines as well as the dateline.

A while ago, I got the new Microsoft fonts such as Calibri, Constantia, and Corbel as part of Office 2008. And today I was surfing around and was impressed with a site using a font called Segoe, a new system/branding font introduced with Windows Vista. So now I first serve up Segoe, followed by Corbel for content and I added Constantia for headlines and dates.

body {
	font-family: Segoe, Corbel, "Lucida Grande",
	"Trebuchet MS", Verdana, sans-serif;
	}

h2, #content p.date {
	font-family: Constantia, Georgia, serif;
	}

I did not modify any of the CSS rules for text size (which is declared using ems from a overall base font-size of 62.5% to make the math easier. See this article for more info). I find that Segoe and Corbel are much easier to read and cleaner looking at my default entry text size of 14px. At least on my Mac, Lucida Grande was a bit large and heavy at that size. The sidebar text is a bit small now, but surprisingly readable at 12px.

With the all the body text updated, Georgia was starting to look somewhat out of place. I hadn’t paid much attention to the new Microsoft serif fonts, but when I saw that Constantia had old-style figures, I gave it a shot and I’m impressed with the results.

Those two minor changes are a breath of fresh air, just when I was thinking the site design was getting a bit stale. Speaking of which. another aspect of this blog that is starting to get stale is Movable Type, even after I upgraded to MT 4. I’ve been messing around with Wordpress and have been impressed. More on that in a later post.

Other Tidbits

The next design-related tweak I want to make is come up with a new header image. ITC Conduit is the typeface used and it could use a update as well. I’ve never been quite happy with the letter-spacing either. I’m no Photoshop guru, so we’ll see…

MT 4 also added the ability to add tags to entries. I went back and tagged some entries without knowing that I still had some leftover default template code in my individual archive template that displayed them. I tweaked that bit and will go back and tag the other entries soon. I think I will still assign posts to categories, but I probably need to update my categories list.

As mentioned below, when I dusted this thing off, I noticed I had accumulated almost 12,000 spam comments. I installed an MT plug-in called Blog Janitor with mixed results. Blog Janitor is supposed to turn off comments on entries older than the user specifies (I set 180 days). Why this capability is not inherent in MT is beyond me. Other users have reported that this plug-in doesn’t appear to work with MT 4. Upon installation I had the same results, until I looked closer and saw that comments were disabled on older posts. However, spam comments are still showing up in those entries. Unfortunately, I don’t have any indications to the reader that explicitly state that comments are off. Also, it doesn’t appear that the plug-in allows me to turn comments back on.

If you see anything else screwed up, please leave a comment and let me know. At least I think comments are on for this…