Posted by Rosie riveter next generation on March 08, 2005
In Reply to: Off plumb posted by R. Berg on March 07, 2005
Before fancy gadgets, quality workmen used a "plumb bob" to help build square and level structures which ALSO were in line with reality. (Probably also where--"on the level" and "square deal" phrases started. No "Tower of Pisa" inclinations.)
A heavy lead "bob" tied to the end of a string would be unwound from it's stick, and allowed to "settle." The pointed tip would give exact spot which gravity said was straight down from the top of the string. Assuming no interference from magnetism, it showed you a straight line to the center of the earth.
This prevented building perfectly 90 degree angled square structures-------which could STILL be faulty because they were out of balance with the world. Basically --- it oriented you to the earth. Hence---being "out of plumb"---shows flawed interface with real world. Being outside plumb lines show lack of centering, alignment.
I was a small girl child when an old workman explained it. I think--but not positive--the line was chalked with blue, snapped against wall, and compared against others further down wall. Mayhaps this also started--"walk a chalk line" meaning VERY straight line! Glad people still wonder and that I remember.