This will require a bit of background, but I'll try to keep it brief. In 1790, Jefferson was asked by Congress to develop new, nationally standardized systems of coinage and measurement for the young republic, which was burdened by an incredible hodge-podge of standards across assorted states and regions. He first tackled coinage, and presented a decimalized system which was swiftly adopted, and which the US uses to this day. His next effort, measurements, was not quite as successful.

Jefferson had been in France at the time that debates over a new, rational, system of measurements had been underway, and he had significant apprehensions about using a measured meridian as the basis of such a system. He favored the use of a timed pendulum rod instead, as this was more egalitarian. The proposal then in vogue in France could only be truly verified in French territory, and to do so would be a significant scientific effort that required the backing of a state. Complaining of this in a letter to the American chargé d'affaires in France, Jefferson wrote -

*The element of measure adopted by the [French] National Assembly excludes, ipso facto, every nation on earth from a communion of measure with them; instead of concurring in a measure which, like the pendulum, may be found in every point of the 45th degree, and through both hemispheres, and consequently in all countries of the earth lying under that parallel, either northern or southern, they adopt one which can be found in but a single point of the northern parallel, and consequently only in one country, and that country is theirs.*

The proposal Jefferson had for measurements was split into a more conservative version, and a radical one. We're going to look just at the radical one to simplify matters.

Plan for Establishing Uniformity in the Coinage said:Let the standard of measure, then, be a uniform cylindrical rod of iron, of such length as, in latitude, in the level of the ocean, and in a cellar, or other place, the temperature of which does not vary through the year, shall perform its vibrations in small and equal arcs, in one second of mean time.

...Let the second rod, then, as before described, be the standard of measure; and let it be divided into five equal parts, each of which shall be called a foot; for, perhaps, it may be better generally to retain the name of the nearest present measure, where there is one tolerably near. It will be about one quarter of an inch shorter than the present foot.

...Let the unit of capacity be the cubic foot, to be called a bushel.

...Let the weight of a cubic inch of rain water, or the thousandth part of a cubic foot, be called an ounce.

This was the basis of the proposed system, and it resulted in the following units, shown below with the equivalents in traditional American and metric units. These numbers come courtesy of Dan of Dozensonline:

***

**Length:**

Point (ten per line) - 11.73 thousandth of an inch - 298.1 microns

Line (ten per inch) - .11 inch - 2.98 millimeters

Inch (ten per foot) - 1.17 inch - 2.98 centimeters

Foot - .97 feet - 2.98 decimeters

Decad (ten feet) - 3.25 yards - 2.98 meters

Rood (ten decads) - 10.72 yards - 29.81 meters

Furlong (ten roods) - 326 yards - 298.1 meters

Mile (ten furlongs) - 1.85 miles - 2.98 kilometers

**Area:**

Rood (100 feet by 100 feet) - .21 acres - 888.5 square meters

**Volume:**

Metre (.001 cubic foot) - .89 fluid ounce - 26.48 milliliters

Demi-pint (.02 cubic feet) - 1.11 pints - 529.7 milliliters

Pottle (.1 cubic feet) - 2.79 quarts - 2.648 liters

Bushel (1 cubic foot) - 6.99 gallons - 26.48 liters

Quarter (10 cubic feet) - 9.35 cubic feet - 264.8 liters

Ton (50 cubic feet) - 46.75 cubic feet - 1.324 cubic meters

Last (100 cubic feet) - 3.46 cubic yards - 2.648 cubic meters

**Weight:**

Mite (.0001 ounce) - .04 grains - 2.648 milligrams

Minum (.001 ounce) - .4 grains - 26.48 milligrams

Grain (.002 ounce) - .81 grains - 52.97 milligrams

Carat (.01 ounce) - 4.08 grains - 264.8 milligrams

Scruple (.05 ounce) - 20.43 grains - 1.324 grams

Ounce (1 square inch rainwater) - .93 ounce - 26.48 grams

Pound (10 ounces) - 9.34 ounces - 264.8 grams

Stone (100 ounces) - 5.83 pounds - 2.648 kilograms

Kental (1000 ounces) - 58.37 pounds - 26.48 kilograms

Hogshead (10,000 ounces) - 583.78 pounds - 264.8 kilograms

***

Jefferson duly submitted his proposed systems of measurements to Congress in 1790. There, they seemed to have suffered more from apathy than hostility, combined with poor timing - military disasters in the Northwest Territory, and a desire to see if anything came of the then ongoing British and French efforts at measurement reform. The relevant Senate committee eventually released a recommendation in early 1792 to adopt the decimalised system of measurement, but it would be fated to die a slow death in the halls of Congress.

However, what if it

*had*been officially adopted at that point?

It seems extremely unlikely that the French would have been budged from their own domestic developments, and would adopt the Metric system, much as they did historically, resulting in two new competing "rational" systems of measurement. Would this result in a patchwork arrangement across the globe over time, with countries selecting the system whose mother nation they had closer economic ties to - so, most of South America going decimal, much of Africa metric? Would the lack of a direct connection to the French make the American system more palatable than metric to certain counties, such as those in the Anglosphere? And would this multi-polar world of measurements encourage the adoption of new systems? One could see the new revolutionary governments in some nations such as the USSR deciding to create their own improved "rational and scientific" systems, splintering the globe even further.

Furthermore, how do you feel such this system would evolve over time? What units would quickly fall by the wayside, and what new ones added? Weight, for instance, seems to end at a relatively low figure. Area was already noted by Jefferson as being in need of further work:

*The head of superficial measures in the last part of the report, is thought to be not sufficiently developed. It is proposed that the rood of land, being 100 feet square, (and nearly a quarter of the present acre,) shall be the unit of land measure. This will naturally be divided into tenths and hundredths, the latter of which will be a square decad. Its multiples will also, of course, be tens, which may be called double acres, and hundreds, which will be equal to a square furlong each. The surveyor's chain should be composed of 100 links of one foot each.*

Well AH, what are your thoughts?