09:09 Oct 9, 2011 

Thank you all for your contributions.

08:59 Oct 9, 2011 

I think you are right Mr. Hassan. A level here is, see this link: http://www.merriam-webster.com/dictionary/level

"plumb line" = خيط الفادن/بلوميت

Thank you - Mohamed

19:33 Oct 6, 2011 

Hello Mohamed,
no it is just my suggestion that you ask about 'a level' to complete the picture, line in plumb line means a thread or a wire not a drawn line.

14:25 Oct 6, 2011 

@ the Asker:
you need that apparatus to determine the perfect vertical projection so you can draw the vertical lines .. you need also to ask about the meaning of "a level" in a separate question because it is another apparatus.