Changes

Traditional systems of measurement all used standard lengths of parts of the human body, or standard distances that a human might walk. The metric system, by contrast, initially used the [[earth]] itself as the ultimate standard.

Traditional systems of measurement all used standard lengths of parts of the human body, or standard distances that a human might walk. The metric system, by contrast, initially used the [[earth]] itself as the ultimate standard.

In 1878 the [[United States]] signed the treaty called the ''Convention du Mètre.'' Since then, ''both'' the metric system and the [[US Customary system]] (miles, inches, pounds, etc.) have had legal status in the US. US Customary units are in fact defined by reference to metric units; that is, legally, an inch is ''defined'' to be exactly 25.4 millimeters.

In 1878 the [[United States]] signed the treaty called the ''Convention du Mètre.'' Since then, ''both'' the metric system and the [[United States customary units]] (miles, inches, pounds, etc.) have had legal status in the US. US Customary units are in fact defined by reference to metric units; that is, legally, an inch is ''defined'' to be exactly 25.4 millimeters.

In international scientific usage, the ''Convention du Mètre'' is superseded by the conventions of the [[International System of Units]]. However, many of the conventions of the metric system survive, including definitions of units that are not, strictly speaking, SI.

In international scientific usage, the ''Convention du Mètre'' is superseded by the conventions of the [[International System of Units]]. However, many of the conventions of the metric system survive, including definitions of units that are not, strictly speaking, SI.