Forum:Now I know why they call it...
a plumbob! well, there is this device called a plumb line. invented by issac newton, this device can determine a point's vertical direction. the thing that is actually hung down from it is called a plumbob. that is also the reason why it is a diamond. here's a picture of it:
http://www.oldschooltools.co.uk/web_images/vintage_brass_plumbob_566g_011.jpg
do you think im right?