Renseignements généraux

Nº de série

S/O

Nº de partie

1

Nombre total de parties

1

Ou

S/O

Brevets

S/O

Description générale

Brass length standard

Dimensions

Remarque : Cette information reflète la taille générale pour l’entreposage et ne représente pas nécessairement les véritables dimensions de l’objet.

Longueur

100,0 cm

Largeur

2,9 cm

Hauteur

S/O

Épaisseur

S/O

Poids

S/O

Diamètre

S/O

Volume

S/O

Lexique

Groupe

Métrologie

Catégorie

Longueur

Sous-catégorie

S/O

Fabricant

Ou

Lenoir

Pays

France

État/province

Inconnu

Ville

Inconnu

Contexte

Pays

Inconnu

État/province

Inconnu

Période

Unknown

Canada

This Lenoir metre is one earliest surviving metric length standards. Canada began official metrification in the 1970s (see key dates below), but it has a long history of using the metric standards that date back to the 19th century. The metric system contains a rich history deriving from revolutionary France. The French realized in the 18th c that a length standard based on an unchanging physical quantity was highly desirable. The metric system proclaimed in 1795 (or Systéme International as it is officially called) grew out of a 1734 attempt to measure the distance between the Earth's equator and its North Pole. The metre was to be defined as one millionth that distance--as it turned out their measurement was very slightly in error. From 1961 the metre has been defined in terms of the frequency of a specific spectral line of the element krypton. Along with the metre, the metric system adopted volume and mass standards based on the metre--the mass being defined as the amount of water held in a standard volume at a standard temperature. Canada's earliest measurement standards were enacted by Frontenac, governor of Quebec, for surveyors in 1674. Two years later, regulations and definitions followed for weights and measures, including the minot, boisseau, pot, pinte, aune, chaîne, romaine, crochet, balance, etc. Following the Treaty of Paris in 1764, Canada's weights and measures were officially tied to those of the British Exchequer. Standards for towns were stamped "G. III, R", while approved tradesmen's measures were stamped "Clerks of the Market". As early as 1795, official standards had been established for Newfoundland, Lower Canada and Upper Canada. These early standards were generally of brass or copper. Such standards were marked, for example, "G.R" (for George III) and "Lower Canada". A checkerboard symbol stamped on early measuring volumes indicated that these were verified at the Exchequer in London before being brought to Canada. At the turn of the 20th century Otto Klotz, a surveyor, come astronomer, in the government service called on the federal government to establish labs to evaluate equipment that was used in the topographic and geodetic surveys of Canada. A lab was established early in the 20th century and worked with the Dominion Observatory that was soon established nearby. However, it is probably to R.H. Field, a scientist at NRC, to whom we probably owe the most in his efforts to establish metrology on a firm and broad base at NRC. He had many international contacts and clearly had a great interest in searching and applying new methods related to setting and maintaining the broadening base of fundamental standards. These now number 7 – length, mass, time, temperature, electric current, luminous intensity and quantity. From these, every other scientifically measured quantity is derived. Now, at the top of the system used to set and regulate measurement and the tools to do this in Canada, is NRCs Institute for National Measurement Standards. INMS is one of just 7 national agencies worldwide whose standards are intercompared to set the internationally accepted values of the 7 fundamental quantities. Historically, length was measured in customary units. The foot was a common unit in many cultures, although the actual length it represented varied. In England, King Edward I made an effort to provide a standard of length by decreeing that the 'Iron Ulna' (taking its name from the bone of the forearm) was to be the main unit of measurement. (This later became the yard.) A measuring stick made of iron was made as a master standard yardstick for the kingdom. By decree, the foot was to be one-third of a yard, and the inch to be one thirty-sixth of a yard. There may have been difficulties in applying this standard; in 1324, Edward II declared "3 barleycorns, round and dry make an inch"; this was probably a more accessible standard for most people. http://www.ukmetrication.com/history2.htm These systems had disadvantages; barleycorns are scarcely uniform, and metal bars expand and contract with rising and falling temperature, as well as being prey to oxidation, unless they are very carefully kept. The French defined the metre in 1791 as one ten millionth of the length of a line, passing through Paris, between the north pole and the equator. The instrument maker Etienne Lenoir constructed a bar of platinum based on this definition to serve as the realization of the metre. In 1887 the physicist Michelson proposed that interferometers be used for the measurement of length. In 1892-93 Michelson and Benoit used interferometers to determine the length of the metre in terms of the wavelength of the red line in cadmium. Thus began a long history of defining length by frequency. The metre is now defined as the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second. This definition, of course depends on the definition of the second. Some day, it may be defined in terms of the wavelength of light emitted by a trapped ion, under very specific conditions. (From the Acquisition Proposal, see Ref. 1)

Fonction

A brass metre stick used as a regional comparison standard for measuring distance. (From the Acquisition Proposal, see Ref. 1)

Technique

Early standard metre signed "Lenoir" and "METRE" and stamped "MODELE" and with a standing figure and with a quarter circle (see photos). This brass meter bar measures 39-3/8" x 1-1/8" x 3/16" (100 x 3 x 0.5 cm) and is divided and number stamped, on one side, every decimeter and every centimetre. The first decimeter is further divided every millimetre. Condition is generally good, the brass now brown and a bit stained, and with numerous scratches in the long direction (particularly on the reverse). But it seems to have survived without serious polishing. It was Etienne Lenoir who was commissioned to construct the first standard meters, specifically defined as one ten-millionth of one-fourth of the terrestrial meridian, based on astronomical observations which determined the length of the polar circumference of the earth. By 1793 Lenoir had constructed a large precise comparator, which would serve well for the production of the provisional brass meter. The next year the Commission Temporaire des Poids et Mesures contracted for Lenoir to provide standard meters (3 cm wide by 5 mm thick, divided in decimeters and centimetres, and the last decimeter in millimetres) to all the French departments and districts, for a total of 660 brass rules (see A. Turner, 1989). But the times were difficult, and materials were in short supply. And it was finally in 1799 that Lenoir's definitive standard meter, made in platinum, was presented to the legislature. The present "Metre-modele" was made by Lenoir c. 1800, designed to serve in an official bureau of verification; it bears the poinçons, the stamps, of Liberte representing the French Republic, and of the quarter circle, representing the definition of the meter in terms of a quarter of the earth's meridian (see Pommier, 2000). An important rule in the history of France and in the development of international standard measures. (From the Acquisition Proposal, see Ref. 1)

Notes sur la région

Inconnu

Détails

Marques

On the proper back, near the centre, is a small stamped quarter circle/ On the proper front, divided from the top edge every cm: "1 2 3 4 5 6 7 8 9 0" repeated across the length/ under each "0" is the marking for every 10 cm: "1 2 3 4 5 6 7 8 9"/ the first 10 cm are divided for every mm, and after that only for every cm/ engraved into the metal at the centre: "METRE"/ to the proper left of centre, in smaller letters: "MODELE"/ at the proper left end is engraved: "Lenoir"

Manque

Appears complete

Fini

Dark brass-coloured metal with darkened areas and brown spots on the surface. The markings are recessed into the metal and darkened to be able to read them.

Décoration

S/O