Who decides how we measure?

To obtain uniformity in measures, weights, and coins, it is necessary to find some measure of invariable length, with which, as a standard, they may be compared. . . .

A standard of invariable length being thus obtained, we may proceed to identify, by that, the measures, weights and coins of the United States; but here a doubt presents itself as to the extent of the reformation meditated by the House of Representatives. The experiment made by Congress in the year one thousand seven hundred and eighty-six, by declaring that there should be one money of account and payment through the United States, and that its parts and multiples should be in a decimal ratio, has obtained such general approbation, both at home and abroad, that nothing seems wanting but the actual coinage, to banish the discordant pounds, shillings, pence, and farthings of the different States, and to establish in their stead the new denominations. Is it in contemplation with the House of Representatives to extend a like improvement to our measures and weights, and to arrange them also in a decimal ratio? The facility which this would introduce into the vulgar arithmetic would, unquestionably, be soon and sensibly felt by the whole mass of the people, who would thereby be enabled to compute for themselves whatever they should have occasion to buy, to sell, or to measure, which the present complicated and difficult ratios place beyond their computation for the most part. Or, is it the opinion of the Representatives that the difficulty of changing the established habits of a whole nation opposes an insuperable bar to this improvement? Under this uncertainty, the Secretary of State thinks it his duty to submit alternative plans, that the House may, at their will, adopt either the one or the other, exclusively, or the one for the present and the other for a future time, when the public mind may be supposed to have become familiarized to it. . . .

There are, moreover, varieties on these varieties, from the barrel to the ton, inclusive; for, if the barrel be of herrings, it must contain 28 gallons by the statute 13 Eliz. c. 11. If of wine, it must contain 31 1/2 gallons by the statute 2 Henry VI. c. 11, and 1 Rich. III. c. 15. If of beer or ale, it must contain 34 gallons by the statute 1 William and Mary, c. 24, and the higher measures in proportion. . . .

The wine gallon, whether of 224 or 231 cubic inches, may be altogether disregarded, as concerning, principally, the mercantile and the wealthy, the least numerous part of the society, and the most capable of reducing one measure to another by calculation. This gallon is little used among the mass of farmers, whose chief habits and interests are in the size of the corn bushel. . . .

But if it be thought that, either now, or at any future time, the citizens of the United States may be induced to undertake a thorough reformation of their whole system of measures, weights and coins, reducing every branch to the same decimal ratio already established in their coins, and thus bringing the calculation of the principal affairs of life within the arithmetic of every man who can multiply and divide plain numbers, greater changes will be necessary. . . .

Measures, weights and coins, thus referred to standards unchangeable in their nature, (as is the length of a rod vibrating seconds, and the weight of a definite mass of rain water,) will themselves be unchangeable. These standards, too, are such as to be accessible to all persons, in all times and places. The measures and weights derived from them fall in so nearly with some of those now in use, as to facilitate their introduction; and being arranged in decimal ratio, they are within the calculation of every one who possesses the first elements of arithmetic, and of easy comparison, both for foreigners and citizens, with the measures, weights, and coins of other countries.

I AM today signing H.R. 8674, the Metric Conversion Act of 1975. This legislation establishes a national policy of coordinating and planning for the increased use of the metric measurement system in the United States.

To say that this legislation is historic is an understatement. The question of a common measurement language is, in fact, nearly as old as our country. President George Washington raised the issue in his first message to Congress on January 8, 1790. He called at that time for a uniform system of currency and weights and measures. He repeated his request several times thereafter.

President James Madison also urged Congressional action on a measurement system. Fifty years later – in July 1866 – Congress did pass legislation making it legal to use the metric system in U.S. trade and commerce.

In 1875, the United States was one of the 17 countries which signed the Treaty of the Meter. In spite of that, the country retained its old measurement system. There have been expressions of legislative interest from time to time since 1875, but no further definitive statement of national policy has been forthcoming.

We should learn from this brief history that legislation cannot solve all our problems. Indeed, if the legislation is not founded on public acceptance, it will have less than no effect at all.

That is why I think this bill is so interesting – because the real impetus came from the private sector, from people in the business of buying and selling American products here and overseas. U.S. industry in this regard is miles ahead of official policy. American companies already are making great use of metric measurements. Many areas of our industry – such as pharmaceuticals, cameras, and space exploration – already are entirely or largely metric. In addition, many of the country's largest retailers are finding it is good business to deal metrically with their customers.

The truth is that our continued use of the English system of measurement was making us an island in a metric sea. In 1965, Great Britain renounced its old system of measurement in favor of metric. It was followed by the Commonwealth countries. Today, more than 90 percent of the world's people uses metric measurement in their everyday lives.

A few years ago, the Congress asked the Secretary of Commerce to determine what impact the increasing worldwide use of the metric system was having on the United States and whether it was desirable to increase the use of metric weights and measures here. The National Bureau of Standards, which conducted that study, urged wider use of the metric measurement language. NBS also proposed a coordinated national program to bring this about. The legislation before us today implements that NBS finding.

It is important to stress that the conversion contemplated in this legislation is to be a completely voluntary one. The Government's function, through a U.S. Metric Board that I shall appoint, will be to coordinate and synchronize increasing use of metric measurement in the various sectors of our economy.

I sign the bill with the conviction that it will enable our country to adopt increasing use of this convenient measurement language – both at home in our schools and factories and overseas with our trading partners.

The MCO [Mars Climate Orbiter] Mission objective was to orbit Mars as the first interplanetary weather satellite and provide a communications relay for the MPL [Mars Polar Lander] which is due to reach Mars in December 1999. The MCO was launched on December 11, 1998, and was lost sometime following the spacecraft's entry into Mars occultation during the Mars Orbit Insertion (MOI) maneuver. The spacecraft's carrier signal was last seen at approximately 09:04:52 UTC on Thursday, September 23, 1999.

The MCO MIB [Mishap Investigation Board] has determined that the root cause for the loss of the MCO spacecraft was the failure to use metric units in the coding of a ground software file, "Small Forces," used in trajectory models. Specifically, thruster performance data in English units instead of metric units was used in the software application code titled SM_FORCES (small forces). A file called Angular Momentum Desaturation (AMD) contained the output data from the SM_FORCES software. The data in the AMD file was required to be in metric units per existing software interface documentation, and the trajectory modelers assumed the data was provided in metric units per the requirements.

During the 9-month journey from Earth to Mars, propulsion maneuvers were periodically performed to remove angular momentum buildup in the on-board reaction wheels (flywheels). These Angular Momentum Desaturation (AMD) events occurred 10-14 times more often than was expected by the operations navigation team. . . . The increased AMD events coupled with the fact that the angular momentum (impulse) data was in English, rather than metric, units, resulted in small errors being introduced in the trajectory estimate over the course of the 9-month journey. At the time of Mars insertion, the spacecraft trajectory was approximately 170 kilometers lower than planned. As a result, MCO either was destroyed in the atmosphere or re-entered heliocentric space after leaving Mars' atmosphere.

The Board recognizes that mistakes occur on spacecraft projects. However, sufficient processes are usually in place on projects to catch these mistakes before they become critical to mission success. Unfortunately for MCO, the root cause was not caught by the processes in-place in the MCO project. . . .

Contributing Causes: 1. Undetected mismodeling of spacecraft velocity changes 2. Navigation Team unfamiliar with spacecraft 3. Trajectory correction maneuver number 5 not performed 4. System engineering process did not adequately address transition from development to operations 5. Inadequate communications between project elements 6. Inadequate operations Navigation Team staffing 7. Inadequate training 8. Verification and validation process did not adequately address ground software . . .

In the case of the ground software, the impulse bit reported to the AMD file was in English units of pounds (force)-seconds (lbf-s) rather than the metric units specified. Subsequent processing of the impulse bit values from the AMD file by the navigation software underestimated the effect of the thruster firings on the spacecraft trajectory by a factor of 4.45 (1 pound force=4.45 Newtons).

During the first four months of the MCO cruise flight, the ground software AMD files were not used in the orbit determination process because of multiple file format errors and incorrect quaternion (spacecraft attitude data) specifications. Instead, the operations navigation team used email from the contractor to notify them when an AMD desaturation event was occurring, and they attempted to model trajectory perturbations on their own, based on this timing information. Four months were used to fix the file problems and it was not until April 1999 that the operations team could begin using the correctly formatted files. Almost immediately (within a week) it became apparent that the files contained anomalous data that was indicating underestimation of the trajectory perturbations due to desaturation events. These file format and content errors early in the cruise mission contributed to the operations navigation team not being able to quickly detect and investigate what would become the root cause.

Metric transition, metric conversion, or metrication are terms used to describe moving from use of local, traditional, or customary units of measure to the SI. Historically, two major approaches have been used: top down or market place decision . . . . A top down decision is usually mandatory. Costs expended by an organization are upfront. Benefits are timely. After the change, only one measurement system is in place. The likelihood of interacting with or encountering legacy measurement systems outside their organizational control may remain for some time. A market place decision is usually voluntary. This approach minimizes upfront costs, which are absorbed into normal operations and represent a "cost of doing business." A significant downside is that it can be a longer-term process that comes with a major risk. Working with multiple measurement systems at the same time can lead to errors and inefficiencies. . . .

Manufacturers develop products and services to meet diverse customer needs and are in the best position to determine when/if metric adoption is good decision for their business; a factor that has shaped U.S. policy to permit either SI or U.S. customary measurements. This places the decision and pace of metric use in the hands of companies as well as the consumers who purchase their products. Industry sectors are moving toward increased SI use at different tempos. Manufacturers that rely on international supply chains are at the high end of the Metric Continuum. However, customary measurement practices continue to be necessary for many small businesses that engage only in intrastate commerce at a local scale.

When U.S. companies begin the metrication process internally, they start by analyzing the costs and benefits, including any long term impacts of not converting to SI measurements. Organizations know their business model and make the best decision for their organization. The inability to produce products, communicate, or provide services using the SI to national and international consumers that prefer or require metric measurements can place an organization at a competitive disadvantage. . . .

While it's true that SI use is mandatory in some countries and voluntary in others, all countries have recognized and adopted the SI, including the United States. There are still countries that are amending their national laws to adopt a mandatory metric policy and others pursuing voluntary metrication. From a technical perspective, it's impossible to avoid using the metric system as all measurement units (including U.S. customary units) are defined in terms of the SI. . . .

One the most significant arguments for the United States moving away from the current dual measurement system to the exclusive use of the SI is a reduction of measurement unit conversion errors. At best, the price of unit conversion calculation errors are expensive. At worst, the consequences can be a matter of life and death. Unfortunately, there are many documented examples of unit mix-ups, including the 1999 crash of the $125 million NASA Mars Climate Orbiter spacecraft. . . .

Using metric practices is a "best practice." Many U.S. industries have quietly gone metric in response to internal or market demands. For example, companies like Caterpillar, General Motors, Xerox, IBM, and Kodak have been metric for years because they export products and use international supply systems. . . .

Significant metrication has occurred when emerging technologies or new product lines enter the U.S. marketplace, developed from the bottom up using metric measurement practices. New technology is a driver of metric adoption. Many manufacturers implement metric transition when new projects are brought online because this is when SI measurements are integrated most efficiently (i.e., as a normal cost of doing business rather than an added expense). Most modern equipment has dual measurement functions and capabilities, providing the user with data in either measurement system.