# Why are grams so small? **URL:** \ **Category:** Factual Questions\ **Created:** [November 6, 2008, 12:06pm UTC](https://boards.straightdope.com/t/why-are-grams-so-small/471436 "2008-11-06T12:06:15Z")\ **Posts on this page:** 6\ **Page:** 7
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [November 9, 2008, 3:05am UTC](https://boards.straightdope.com/t/why-are-grams-so-small/471436/121 "2008-11-09T03:05:02Z")
> [@](#): > > In any case it would be a fascinating read to know how the first IPKs where made in the 18th and 19th centuries. It doesn’t really answer your question, but I came across [this description](http://museum.nist.gov/object.asp?ObjID=38) earlier. I thought it was interesting that they made a bunch at once, and then just picked one of them to be the international standard, with the rest becoming national standards: > [@](#): > > After the Treaty of the Meter had been signed in 1875, the International Bureau of Weights and Measures (BIPM) in Sevres, France, procured 43 prototype kilograms of platinum-iridium in the form of right circular cylinders of equal diameter and height (approximately 39 mm) with slightly rounded edges. One of the group, having essentially the same mass as the kilogramme des Archives, was selected as the International Prototype Kilogram, and is now maintained at BIPM. National Prototype Kilograms No. 20 and No. 4 were received by the United States from BIPM in 1890. After The Mendenhall Order in 1893, Kilogram No. 20 became the primary national standard for all mass measurements. Its mass relative to the International Prototype Kilogram was reported as 0.999 999 961 kg. The reported displacement volume at a temperature of 0°C was 46.402 cm[sup]3[/sup]. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 9, 2008, 7:27am UTC](https://boards.straightdope.com/t/why-are-grams-so-small/471436/122 "2008-11-09T07:27:03Z")
> [@](#): > > Yep, you’re correct, of course. But the assumption is that no other force is acting on it besides mass\*gravity. You mean, aside from the buoyant force you’ve been talking so much about? ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [November 9, 2008, 4:03pm UTC](https://boards.straightdope.com/t/why-are-grams-so-small/471436/123 "2008-11-09T16:03:18Z")
> [@Chronos](#): > > You mean, aside from the buoyant force you’ve been talking so much about? Well, right… 😉 ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [November 9, 2008, 4:04pm UTC](https://boards.straightdope.com/t/why-are-grams-so-small/471436/124 "2008-11-09T16:04:24Z")
(NM) ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [November 10, 2008, 2:13pm UTC](https://boards.straightdope.com/t/why-are-grams-so-small/471436/125 "2008-11-10T14:13:12Z")
> [@Spectre\_of\_Pithecanthropus](#): > > Any balance type scale measures mass. Go to the moon, take along a laboratory balance and set of gram weights, and you’ll find everything has the same mass there as it does on Earth. I’m not sure but I think a standard springless medical scale would be the same. No it doesn’t. That’s the point of the last page of posts. A balance type scale doesn’t adjust for buoancy. (Neither do scales that measure force.) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 10, 2008, 5:55pm UTC](https://boards.straightdope.com/t/why-are-grams-so-small/471436/126 "2008-11-10T17:55:45Z")
But for most objects, buoyancy is negligible, and in any event nobody said that we were in different atmospheres on the Earth and the Moon. You could do your measurements in a vacuum chamber on Earth, or in a sealed habitat on the Moon, and the balance scales wouldn’t care whether you were on the Earth or Moon. Any spring-type scale, though, would give very different readings on the Earth and Moon. [Previous page](https://boards.straightdope.com/t/why-are-grams-so-small/471436.md?page=6)