Fergusson, James: A history of architecture in all countries, from the earliest times to the present day: in five volumes (Band 3) (London, 1899)

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INDIAN SARACENIC ARCFIIT ECTUKE. Book VI].

vault that will stand. As the dome is also, artistically, the most
beautiful form of roof yet invented, it may be well, before passing
from the most extraordinary and complex example yet attempted
anywhere, to pause and examine a little more closely the theory of
its construction.

Let us suppose the diagram to represent the plan of a perfectly
flat dome 100 ft. in diameter, and each rim consequently 10 ft. wide.
Further assuming fur convenience that the whole dome weighs

7850 tons, the outer rim will weigh 2826 tons, or almost exactly as
much as the three inner rims put together; the next will weigh 2204,
the next 1508, the next 942, and the inner only 314; so that a con-
siderable extra thickness might be heaped on it, or on the two inner
ones, without their preponderance at all affecting the stability of the
dome ; but this is the most unfavourable view to take of the case. To
understand the problem more clearly, let us suppose the semicircle
A A A (Woodcut No. 324) to represent the section of a hemispherical