|MadSci Network: Science History|
My educated guess is that you have a surveyors tape. Surveyors have used feet and tenths/hundreths of feet as standard units of measure for quite some time. Furthermore, the "CAN 1943" provides additional evidence because surveyors are notorious (and rightly so) for documenting the origins of their measurements - especially with a place and date. This is because in the surveying field, so many different standards have been (and still are) in use. (I trace this to the fact that the Earth is round and we humans are always trying to turn it into a flat measure. If you look at Datums (definitions of the coordinate systems used by surveyors) there are probably 300 or so that have been in common use in some part of the world and each is identified by a name (often a place name) and a date (e.g., North American Datum 1923).) Because there were different feet (US feet, Imperial feet, and international feet) in use at the time, the mfr of the tape probably serviced the surveying community and wanted to be sure that the user knew which kind of foot was on the tape. This would probably only be noticed by a surveyor, but has implications for us commoners, as well.
From the following web site:
"The international (S.I.) foot, based upon a redefinition of the meter in 1959, is equivalent to 0.3048 meter. The U.S. Survey Foot, upon which many years of land tenure information and legislation are based, retained the 1893 definition of 1200/3937 meter*. "
From http://www.delorie.com/gnu/docs/units/units.man.html "The US Survey foot, yard, and mile ... differ slightly from the international length units. They were in use until 1959, but for geographic surveys, they are still used. The acre is officially defined in terms of the US Survey foot. ... The difference between these units is about 4 parts per million. The British also used a slightly different length measure before 1959. "
One other application, of which I am aware, is measuring water levels. This, of course, is somewhat related to surveying and was probably introduced by the same civil engineers that set the standards for surveying.
Since Canada no longer uses imperial measures, (they are strictly on the Metric system), you have an interesting antique, there, that may be of historic value to a surveying museum.
Thanks for your question.
Todd Jamison, Chief Scientist, Observera, Inc.