Technology can tempt us to snub mental math and to trust machines to tell us everything. Well, call me old-school, but I like keeping my brain engaged in reality’s texture. For those of similar mind, I’m going to mention a few basic tidbits that have proven useful when straddling the worlds of metric measurements and English measurements. Saipan often juggles both worlds.
Actually, I don’t even know if “English” is the correct term for the system of measurement that I’m calling “English,” but I’ll use it anyway.
These tidbits are only useful if they’re easily remembered, so this is an exercise in minimization.
Temperature: My temperature tidbit is a favorite with pilots. It’s also important when serving tourists. I’ve mentioned it before. You can get a ball park conversion from Celsius to Fahrenheit by doubling the Celsius and then adding 30. Thus, 27C becomes an estimated 84F. The precise answer, for comparison, is 80.6F. The two figures are certainly close enough for advising a client on how to pack for a trip, and this technique is also useful as a sanity check on precise calculations.
Length: One useful tidbit is the fact that there are 2.54 centimeters to the inch. That’s such a commonly-used number I think it’s often memorized. For mental math it’s easy to round it to 2.5.
Another tidbit is that a 10K run (a common distance for such things; the “K” means kilometers) is equivalent to 6.2 miles. Of course, if you’re going to travel 6.2 miles you might as well get some lunch while you’re at it, so it makes sense to fire up the car and hit the drive-through.
Well, so far, so good, but what sticks in my craw is going between yards and meters, or feet and meters. This can be a headache for a fast conversion. The best I’ve come up with is that a meter is about 10% longer than a yard, but when I’m in these situations I usually need an exact answer so I wind up scrambling for a pencil or calculator.
Weight: There are 2.2 pounds in a kilogram. I think that a kilogram is technically a unit of mass, while a pound is a unit of weight, but I’m not a scientist so I don’t have to care.
Volume: There are 3.8 liters in a U.S. gallon. While this is certainly no secret, I don’t think many people keep it in mind.
Gallons are tricky things, since there’s also an “Imperial” gallon used by the British. I’ve never paid any attention to this. However, if I get the E-type Jaguar I’ve always wanted, I’ll revisit the issue.
Summary: In summary, then, some basic tidbits that have stood the test of time, at least in my noggin, are: Double it and add 30; 2.54; 6.2; 10%; 2.2; and 3.8. Presented in this thumbnail manner, the information can be used to test ourselves on the relevant contexts and related information.
I suspect that the English system will continue to decline in relative importance to the metric system. After all, the long-term trajectories of the underlying economies certainly favor the latter.
But for the sake of posterity, I’ll mention there’s some human-scale wisdom behind an inch being the width of a thumb; a foot being, well, about as long as a foot; and a mile being 1,000 paces. On that last note, the term “mile” is derived from the Latin “milia” for thousand.
If you read the British press you’ll encounter the term “stone,” which equates to 14 pounds of weight. Now you know. For some reason, I have never been able to memorize this simple fact. I guess the rocks in my head don’t have room for one more stone.
But there is room in the garage for an E-type Jaguar, so I’ll just keep dreaming of using one for my next 10K run.
Speaking of measurements, I’m going to refine some rough items from last week’s column about the Orion constellation. I referred to the star Rigel as white. Then I mentioned that Rigel is a blue supergiant. So, what’s up? Well, the “blue supergiant” designation is a technical specification that came from a NASA Web page. By contrast, in my very non-technical stargazing, Rigel seems more whitish than blue, hence the white in my observational notes. I also mentioned that our solar system sits on the Orion Spur, also known as the Orion Arm, of our galaxy. I should have also mentioned that our galaxy is called the “Milky Way.”