302 Unrolling of the Herculanean Manuscripts 
computed ; and the more, the longer the beam. Jn some of his 
experiments, the angles which the beams made with the horizon 
must have been very considerable. 1 ie 
HERCULANEAN MANUSCRIPTS. 
Sir Humphry Davy has turned his attention to this subject, 
and seemingly with much promise of success. It occurred to him 
that a chemical examination of the nature cf the MSS. and of 
the changes they have undergone might offer some data as to the 
best methods to be attempted for separating their leaves, and 
rendering their characters legible. Some fragments having been 
submitted to experiment, he was soon convinced that they had 
not been carbonized by the operation of, fire, but were in a state 
analogous to peat or Bovey-coal, the leaves being cemented to- 
gether by asubstance formed during the fermentation and change 
of the vegetable matter of which they were composed. Having 
ascertained the nature of this substance, the next desideratum 
was to discover means to destroy the cementing substance with- 
out injury to the characters or destroying the texture of the MSS.; 
and in thishe happily succeeded. After the chemical operation, 
the leaves of most of the fragments perfectly separated from each 
other, and the Greek characters were very distinct. He found 
however in one fragment the leaves easily separated, but the 
characters defaced on the exterior and partially so in the interior 
folds: in another, though the characters were legible on the 
*leaves that separated, yet an earthy matter, a species of tufa, 
prevented their separation in some parts—circumstances that 
were clearly the results of agencies to which the MSS. had been 
exposed, during or after the volcanic eruption by which they had 
been covered. An examination of the excavations that still re- 
main open at Herculaneum, confirmed the opinionthat the MSS. 
had’not been acted on by fire. These excavations are in loose 
tufa, composed of ashes, sand, and fragments of lava, imperfectly 
cemented by ferruginous and calcareous matter; and from the 
manner in which this tufa is deposited in the galleries of the 
houses, there can be little doubt that it was the result of torrents 
laden with sand and volcanic matter, accompanied with showers 
of ashes and stone. From the state of the buildings, it appeared 
evident to Sir Humphry that they had never been exposed to 
any degree of heat capable of converting vegetable matter into 
charcoal: from the state of the MSS. it is inferred that they 
were probably on shelves of wood, which were broken down when 
the rocfs of the houses gave way to the superincumbent mass ; 
and hence many of them were crushed and folded in a moist 
state, and some pressed ina perpendicular direction. They must 
all have been acted on by water; and as the ink was gue of 
nely 
