2

ponent parts of the hill, as they were originally placed in situ by the workmen (whoever they were) and as they were revealed by the tunnel which penetrated to the centre in 1849 under the auspices of the Archæological Institute.1 It will be seen that at the nucleus of the mound these several materials lie in regular layers, (or segments of concentric circles) as they must have been taken from the surrounding ground and there deposited: the curve of the strata plainly showing the commencement of the accumulation, by which this gigantic tumulus had been formed: 3 thus we have 1st, (at a) Light rubble with flints and chalk. 2nd, (at b) Dark clayey rubble with flints.

3rd, (at c) Decayed peat with moss and shells.

4th, (at d) Light chalky rubble, forming the general mass of the hill.

Nor is this all which the tunnel has revealed, for it exposed the undisturbed surface, just as it existed before the vast superincumbent mass was placed upon it, showing throughout its entire length, 1st, (at e) The ancient original turf.

2nd, (at ƒ) The original soil (viz: clay with flints). 3rd, (at g) The original chalk undisturbed.

"On Tuesday the 10th July the excavation of the gallery was commenced: from this time gangs of workmen succeeded each other at stated intervals, so that the work proceeded day and night without interruption. By Friday evening the 13th, the tunnel had extended to 94 feet from the entrance, about one-third of the whole intended length, by which it was calculated the centre of the hill would be attained. The work thus far was carried through the natural soil, a vein of hard undisturbed chalk, and proceeded in an upward direction, at an inclination of 1 in 28: the artificial soil was cut into at 33 yards from the entrance: the work was then carried on through 18 inches of the artificial earth and 5 feet of the original soil, presuming that by this means any sepulchral remains must be discovered if they existed. The excavation was carried in this way 54 yards, at which distance, according to the survey made, the original centre of construction, or true centre of the hill would be attained." [Examination of Silbury, in Salisbury Volume, p. 300.]

2 Archæological Journal, vi., 307.

3"The turf was quite black, as was also the undecayed moss and grass which formed the surface of each layer, and amongst it were the dead shells, &c., such as may still be found in the adjoining country." [Salisbury Volume of the Archæological Institute, p. 301.]

4 Illustrations 2 and 3 are copied from the Salisbury Volume of the Archæological Institute.