XXVI Congreso Internacional de Americanistas

tound, suggests that some eombination of val1lting and other roofing 111eans
\Vas used. The walls of the J-17 ehamber eould be traeed to a height of
0111y .65 m, and there the slight amount of debris Jead s us to suppose that
no vaulting at all \Vas used. We believe from these three eases that where
. vaulting \Vas used for these chambers, either in compl'ete 01' l110dified
form, it sprang at a very low leve!. Where it was not used the evidence
of debris indicates wallsof no great height.
The Central Chamber is furnished, in aU eight cases, with a centrally
placed front doorway. In three cases, Structures P-7, N-l and J-17,
this is knawn to be the only door;way, and it probably 'was in al1. The
door\Vay widths vary from .70 to 1.00 111. This is significant at Piedra~
Negras when compared with buildings of other types. These are usually
provided with thr'ee 01" more front door,wais, at least one of 'Which is in
cases over 1.20 m wide. Nearly all have one or more doorways much
wider than this, the maximum, in Structure 0-18, being 3.71 m.
In the three cases where the doorway height has been c1etermined, it
is very low --75 m in Structure N-l, 1.10 m in Structures P-7 and S-4·
From the positions of the lintels in three more, Structures 0-4, R-I3
and S-19, we may say that those doorways are also very low, but further
excavation is necessary for precise knowJedge. The jambs in J-17 and
S-2 had partial1y fallen. It seems safe to say that in all cases it was
necessary to stoop in order to entero
In the only case where the roof was standing eStructure P-7) there
was no ventilating opening other than the doorvvay, unless on one side
only, where vandals have broken through a large hole and so made it
impossible to sayo
The doorway of the P-7 chamber was secondarily reduced by raising'
the floor level within it 20 cms; that in N -l was almost surely similarIv
l educed by the same amount; and there is (as yet uncertain) evic1encc
that Structl1re 0-4 w as treated in the same way. It is therefore clea r
that, \Vhether there were sma11 ventilators or not, tbe central chambers
\\ere extremely clark and ill ventilatecl, not only in contrast to builclings
of the region gene rally, but in contrast to the rooms with which [hey
were directly associated and used.
In the four cases where excavation has extended to the interior oE
the central chamber, its floor has be en found split in two by a sunken
passage, leading back from the doorway to the fire-chamber to be discribed
below. This passage is in all cases equal to the width of the
doorway. Its original depth thus far has varied from .30 to 50 cms. IJ:1
three cases, Structures P-7, N-l and J-17, the f100r level of the chamber
is lbe same as that of a front gal1ery outside, ancl the passage extends
through this also, from the front of the doonvay to the stairway. Since
the passage has been identified outside the R -13 doorway, we are justified
in supposing its presence willbe revealen insicle also. It does not