## The State of the Unit: The Kilogram (Documentary Film)

A documentary film about the Kilogram and the scientific efforts to redefine it.
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174 backers pledged \$27,038 to help bring this project to life.

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## Research highlights in public understanding of metrication (which is more photogenic than it sounds)

Dear Friends,

As one of my aims for the State of the Unit is to help the general public understand what the redefinition of the kilogram will mean (and how it came about), I am naturally interested in examples of public instruction on measurement. There is quite a precedent in the history of the kilogram. Michael Trott, the film's science advisor, has bought some books—very, very old books, i.e., 1790s—that teach the newly invented and launched metric system to the general public of France.

On the film's blog, I have put together some thoughts about the public instruction one can glean from these books and from the demands for standardized weights and measures published the summer before the French Revolution: "Metrication in 1790s France: When people got what they asked for, but not what they wanted

Things are going well for me and this project, and I hope you enjoy the blog post. Scroll down for many pictures of the books! :D

Sincerely,

Amy

## A bit more live-action filming: Colonial measures and education in Early America

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Dear Friends,

After learning about standardization in 1790s France in everything from measures to education, I became interested in what was taught in the American Colonies and early United States. At that time, we used measures and currency from many countries, and bartering was common in business.

I was happy and lucky to find two experts in Colonial and Early American mathematics education: Nerida Ellerton and Ken Clements, both math professors at Illinois State University. In addition to their regular teaching and advising, Nerida and Ken have studied and compared 500+ cyphering books from 1650-1861.

Cyphering books are self-written reference books; students would solve problems on slates, and after reaching the correct answer, students would record the full problem in their own cyphering book.

I met with them first last October, and everybody's schedule finally aligned and I was able to film them last week. Here's some stills, below.

And if you're interested in this topic with more photos, see the film blog

Sincerely,
Amy

This cyphering book is one written by a girl student—about 20% of the cyphering books studied these professors were written by girls. The cover is blue fabric, reinforced with newspaper.

## Celebrating World Metrology Day 2016!

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There's little uncertainty that metrologists are enjoying their day! Here's a video I made to celebrate, Part 2 of "Build Your Own Watt Balance". After making Part 1, I received a question about how the experiment yields Planck constant, and another question about how IPK is connected to the forthcoming quantum standards. Hope this explains it!

https://vimeo.com/167492608

## Mirror, Mirror on the wall, who's the cutest kilogram of all?

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Dear Friends,

I am working on some stop-motion animation footage, to show what I call the "Migration of the Kilograms" — when in 1889 kilograms were assigned to the 17 countries who signed the Metre Convention of 1875. I made some replicas of that batch of kilograms. Here you see a miniature of Kilogram 8/41. They made 40 kilograms and engraved each with a number. When they got to the end, they had one leftover and no number '8'. So this one is engraved with '41'. (The replica shown below is made of clay and not engraved with anything other than my fingerprints.)

Richard Davis told me this story of K8/41 and I like the contrast of über-precise kilograms and a simple mistake in counting to 40. He gives details about the kilograms histories and the Metre Convention in his paper "The SI unit of mass," Metrologia 40 (2003) p. 299–305. His paper also includes two photographs of the témoins, which is French for witness, second, or best man. The témoins live in the same vault with the IPK, in an undisclosed location at the BIPM.

Unlike my clay miniatures, they are "real copies" of the IPK—which seems to me an oxymoron.