Thanks. One way of promoting SI is by showing the value of a standard system of units. I'm collecting information about "systems" of units so when people refer to the "English System" or "inch-pound system" I can ask them "which one?" --
Apothecaries System Avoirdupois System British Absolute System British Engineering System British Gravitational System (aeronautical, civil, and mechanical engineering versions) English Engineering System [U.K. and U.S. versions] Foot-Pound-Second System [U.K. and U.S. versions] Imperial System Inch-Pound-Second System [U.K. and U.S. versions] Troy System U.S. Customary System -- and how force and mass are distinguished and whether units of length are international, nautical, statute, or survey. Those who don't use SI are often confused (or clueless) about these things. Ralph Gillmann Federal Highway Administration -----Original Message----- From: [EMAIL PROTECTED] Sent: Tuesday, June 03, 2003 1:42 PM To: [EMAIL PROTECTED] Subject: [USMA:25910] Re: Systems of Units Ralph Gillmann asked in UDMA 25906: >What non-metric systems of units have been used in science or >engineering? I mean real systems, not hodge-podge collections of >units. Where are these systems documented? I've seen references to >the following: > >British Absolute System >British Gravitational System >English Engineering System >Foot-Pound System >Inch-Pound System > >But there is very little information about what these "systems" are. > >In trying to promote the specification of SI in standards, I've made >the point that if non-SI units are used, then a standard document >should be referenced which defines the system and its use. Since >such documents don't seem to exist, I then want to make the point >that an engineering system of units needs to be specified, not just >a vague term such as "inch-pound units." > >Ralph Gillmann >Federal Highway Administration The British Absolute System was used by physicists. Its unit of mass was the pound and its unit of force was the poundal = pound-force / 32.2. The British Gravitational System was really two system. Mechanical engineers used the pound-force and the pound-mass. In this system pounds-force = pounds-mass x acceleration / g. The aeronautical engineers used the pound-force and the slug-mass = 32.2 pounds-mass. Civil engineers used the foot as their unit of length, while mechanical engineers used the inch as their unit of length. The metric system followed a similar evolution. In 1832 K. F. Gauss proposed that the electric units should be based on the millinetre, milligram and second. In 1873 to the British Association for the Advancement of Science proposed elctrical units based on the centimetre, gram and second. The first Congr�s International d'Electricit� in 1881 adopted this system and named it the CGS System (cenitmetre-gram-second). In France the MTS (metre-tonne-second) system was legal from 1919 to 1961. Engineers also used the metre-kilogram(force)-second system. In 1901 the Italian engineer Giovanni Giorgi propoed a system based on the metre, kilogram and second and an elctrical unit to be chosen. This system was adopted in 1935 by the Commission Electrotechnique Internationale. The amp�re was selected in 1950 as the 4th unit. The Giorgi system was adopted by the Conf�rence G�n�rale des Poids et Mesure in 1948, and, with the addition of other units in 1960 was named the "Syst�me International d'Unit�s" designated as "SI" in all languages. -- Joseph B. Reid 17 Glebe Road West Toronto M5P 1C8 Telephone 416-486-6071
