They were presumably intended to safeguard the King's Chamber from the possibility of the roof collapsing under the weight of stone above; hence they are referred to as "Relieving Chambers".
The granite blocks that divide the chambers have flat bottom sides but roughly shaped top sides, giving all five chambers an irregular floor, but a flat ceiling, with the exception of the uppermost chamber which has a pointed limestone roof.[184]
Nathaniel Davison is credited with the discovery of the lowest of these chambers in 1763, although a French merchant named Maynard informed him of its existence.[185] It can be reached through an ancient passage that originates from the top of the south wall of the Grand Gallery.[184] The upper four chambers were discovered in 1837 by Howard Vyse after discovering a crack in the ceiling of the first chamber. This allowed the insertion of a long reed, which, with the employment of gunpowder and boring rods, opened a tunnel upwards through the masonry.[186] As no access shafts existed for the upper four chambers – unlike Davison's Chamber – they were completely inaccessible until this point.
