It was discovered that the plinth of the mausoleum on
the northern side (or the riverside) is lower than on the south by 3.5cms.
Cracks were not noticed on the exterior wall, but they were definitely
present on the second storey vaults of the marble structure and, on a much
larger scale, in the underground vaults below the northern side.
The architect of the Taz Mahal aimed at giving maximum strength and
stability to the tomb and worked out the minutest details with utmost
precision : the weight of the entire structure is uniformly distributed,
extraordinarily massive piers and vaults were constructed to support this
heavy load, the very best quality of bonding material helped combat the
disrupted tensile stress etc.
However, in spite of all these precautions and care, dangerous cracks and
leakages developed in the substructure of Tag Mahal just after four years of
its completion. Aurangzeb in his letter to Shah Jahan in 1652 mentions these
cracks. Some defects were discovered about the same time in the dome. Though
thorough repairs were undertaken, the nature of the cracks was not
discovered. The cracks were again noticed to have developed to dangerous
proportions in 1810. As a result an Advisory Committee on the restoration
and conservation of the monument was set up and a survey with reference to
the damage was undertaken.
Taz Mahal structure which stands on the edge of water has a natural
tendency to move towards the more open side, the higher edge always acting
as a strong buttress, thrusting it in the opposite direction. It is the
whole mass, and not a part of it, that is gradually sinking. This is what
can justifiably be concluded from the available data.
The long series of cracks in the underground vaults may be due to the
crushing of lime on account of the excessive weight, or as seems more
probable, this may be due to the sinking of the whole structure towards the
riverside!! Such a sinking would shift the load out of balance slowly and
gradually and the unequal settlement would crack the weak points,
particularly the summit s of the vaults and arches, which is actually
happening in the underground chambers.
