The teams of masons at work on the

the teams of masons at work on the dome had certain basic measuring
devices at their disposal. most of these had not changed significantly for a
thousand years. for checking the perpendicularity of walls, for example,
they used plumb-lines: a string on which a weight, usually a ball of lead,
was suspended. the string would be braided like a fishing line in order to
.prevent the weight from rotating in the breeze. and to ensure the stones
were laid in perfectly horizontal courses or layers, a mason's level was
employed. this instrument was shaped like the letter a: a plumb-line hung
from its apex, while the horizontal cross-piece was inscribed with a
graduated scale. the plumb-line would come to rest in the centre of the
.

The teams of masons at work on the dome had certain basic measuring
devices at their disposal. Most of these had not changed significantly for a
thousand years. For checking the perpendicularity of walls, for example,
they used plumb-lines: a string on which a weight, usually a ball of lead,
was suspended. The string would be braided like a fishing line in order to
prevent the weight from rotating in the breeze. And to ensure the stones
were laid in perfectly horizontal courses or layers, a mason's level was
employed. This instrument was shaped like the letter A: a plumb-line hung
from its apex, while the horizontal cross-piece was inscribed with a
graduated scale. The plumb-line would come to rest in the centre of the
cross-piece when the stone or brick was on a level plane.

The teams of masons at work on the dome had certain basic
measuring devices at their disposal. Most of these
had not changed significantly for a thousand years. For checking perpendicularity of the walls, for example,
they used plumb-lines: a string on which a weight, usually a ball of lead,
was suspended. The string would be like a braided fishing line in order to
prevent the weight from rotating in the breeze. And
to ensure the stones were laid in courses or perfectly horizontal layers, a mason's level
was employed. This instrument was shaped like the letter A: A plumb-line
hung from its apex, while the horizontal cross-piece was inscribed with a graduated scale
. The plumb-line would come to rest in the center of the
cross-piece when the stone or brick was on a level plane.