Furlongs per Fortnight

By The Metric Maven

At the first university I attended, it was assigned as a “joke exercise” to compute speeds in Furlongs/Fortnight. I’m not sure what the lesson was supposed to be in this case. It was clear Furlongs per Fornight was an absurd use of units, but was it because they were not metric?—-or because they are an “inappropriate” use of medieval units. My favorite reference book, Measure for Measure has a single conversion factor entry: Furlong/Fortnight -> miles/hour [Campbell Factor] 0.00 372, and thus far I have not discovered who Campbell might be, or have been. So assuming I’ve converted correctly 1 Furlong/Fortnight is 166.31 micrometers/second or about 10 mm per minute and 600 mm per hour. For those who want to add more absurdity, and for those who are just fine with US Customary, there is the FFF system, which uses the Furlong, Firkin and Fortnight as its base units.

Of course, this is just a contrived use of units that is clearly absurd right? Clearly, one would never encounter an everyday computation this absurd. Well, then you underestimate the absurdity of our “customary units.” I often look to see what search terms are used by visitors to The Metric Maven website, and the current list looked rather prosaic, until I hit the sixth entry. It reads: “How many tablespoons are in a quarter cup?” My mind lurched to a halt taking this in. In one question we find so many adverse aspects of the current non-system of measurement it requires elaboration.

First we address the tablespoon issue. Now I hope the person asking is sure it is a tablespoon and not a teaspoon. As I’ve addressed in the past, the confusion of teaspoons and tablespoons is a perennial problem in US kitchens. It also has the downside that it has the potential to kill people. Assuming the inquisitor wants tablespoons, we might just quickly convert it to metric in milliliters. A tablespoon is 14.8 mL which I will round to 15 mL for our purposes.

We next encounter a fraction to dilute the volume of the cup for reasons which are not particularly apparent. It’s quite possible, that the person involved needs 1/4 cup of water for say a taco mix recipe or something, but has only teaspoons and tablespoons in their post-high school flat, and no US measuring cups. Well, we want a quarter cup of liquid, but only have a tablespoon. So a cup converted to metric is 236.6 mL, and we will divide this by four to obtain 59.1 mL which we will round to 60 mL. I might hear some objecting to this, but if the recipe was born of precision, it would have been in metric in the first place.

So now we have a teaspoon is 15 mL and 1/4 cup is 60 mL, we use these integer values to see that wow!–it’s 4 tablespoons in a 1/4 cup! What an interesting coincidence, but also, yeah, a complete coincidence. There is no way that these medieval units would have allowed one to readily realize this fact using them exclusively.

Now let’s look at the same problem from a metric perspective. We need 60 mL of water, milk, olive oil, whatever. Well, we can find a 15 mL measuring spoon and use four of them, or we can find a measuring cup and fill to the 50 mL graduation, then estimate another 10 mL. In the case of water, you could use a scale to measure 60 grams of water which is 60 mL using any vessel after zeroing the scale. It seems like one has a lot of options with a rational measurement system. But why bother when you can just use a search engine to find out the answer? The same type of solution was offered in the early 20th century by Fredrick Halsey, author of The Metric Fallacy. The technical device he offered up that would make the metric system unnecessary was the slide rule.

Technical innovations will not eliminate poor and non-intuitive methods of measurement expression. For instance, another question in the list of search key phrases is “how to use 1/8 inch measurement on yardstick.” Well, I have written about the absurdities of yardsticks in my essay Stickin’ it to Yardsticks. US residents might find it absurd that a person doesn’t recall common denominators, and such. What is absurd is making US residents use fractions on measuring rules at all. If they had a millimeter-only meter-stick there would be no need for fractions, or decimals. The person involved would not need to look on the internet, only understand integer addition and subtraction, and there are plenty of calculators available for that.

Thank heavens we still don’t use Roman numerals when the rest of the world uses Hindu-Arabic ones with decimals, we might rationalize using them in the age of the internet.


Tim Hunkin, a designer and maker from the UK has released his first video about The Secret Life of Components. He discusses chains, and as you will see, uses nothing but millimetres, including a mm-only ruler. He threw out all his quarter-inch US chains as he found the use of “imperial” too confusing. Note that he uses the word mil for millimetre, as is common with British engineers. In the US, the mil is a feral unit. Of course, we also use a pre-metric measurement unit called the chain to build roads in the US. I’ve written about it here.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page.