the formation of vegetable mould-第20部分
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remains of many ancient buildings in England have been buried so
effectually； in large part through the action of worms； that they
have been discovered in recent times solely through various
accidents。 The enormous beds of rubbish； several yards in
thickness； which underlie many cities； such as Rome； Paris； and
London； the lower ones being of great antiquity； are not here
referred to； as they have not been in any way acted on by worms。
When we consider how much matter is daily brought into a great city
for building； fuel； clothing and food； and that in old times when
the roads were bad and the work of the scavenger was neglected； a
comparatively small amount was carried away； we may agree with Elie
de Beaumont； who； in discussing this subject； says； 〃pour une
voiture de materiaux qui en sort； on y en fait entrer cent。〃 ｛53｝
Nor should we overlook the effects of fires； the demolition of old
buildings； and the removal of rubbish to the nearest vacant space；
Abinger； Surrey。Late in the autumn of 1876； the ground in an old
farm…yard at this place was dug to a depth of 2 to 2。5 feet； and
the workmen found various ancient remains。 This led Mr。 T。 H。
Farrer of Abinger Hall to have an adjoining ploughed field
searched。 On a trench being dug； a layer of concrete； still partly
covered with tesserae （small red tiles）； and surrounded on two
sides by broken…down walls； was soon discovered。 It is believed；
｛54｝ that this room formed part of the atrium or reception…room of
a Roman villa。 The walls of two or three other small rooms were
afterwards discovered。 Many fragments of pottery； other objects；
and coins of several Roman emperors； dating from 133 to 361； and
perhaps to 375 A。D。； were likewise found。 Also a half…penny of
George I。； 1715。 The presence of this latter coin seems an
anomaly； but no doubt it was dropped on the ground during the last
century； and since then there has been ample time for its burial
under a considerable depth of the castings of worms。 From the
different dates of the Roman coins we may infer that the building
was long inhabited。 It was probably ruined and deserted 1400 or
1500 years ago。
I was present during the commencement of the excavations （August
20； 1877） and Mr。 Farrer had two deep trenches dug at opposite ends
of the atrium； so that I might examine the nature of the soil near
the remains。 The field sloped from east to west at an angle of
about 7 degrees； and one of the two trenches； shown in the
accompanying section （Fig。 8） was at the upper or eastern end。 The
diagram is on a scale of 1/20 of an inch to an inch； but the
trench； which was between 4 and 5 feet broad； and in parts above 5
feet deep； has necessarily been reduced out of all proportion。 The
fine mould over the floor of the atrium varied in thickness from 11
to 16 inches； and on the side of the trench in the section was a
little over 13 inches。 After the mould had been removed； the floor
appeared as a whole moderately level； but it sloped in parts at an
angle of 1 degree； and in one place near the outside at as much as
8 degrees 30 minutes。 The wall surrounding the pavement was built
of rough stones； and was 23 inches in thickness where the trench
was dug。 Its broken summit was here 13 inches； but in another part
15 inches； beneath the surface of the field； being covered by this
thickness of mould。 In one spot； however； it rose to within 6
inches of the surface。 On two sides of the room； where the
junction of the concrete floor with the bounding walls could be
carefully examined； there was no crack or separation。 This trench
afterwards proved to have been dug within an adjoining room （11 ft。
by 11 ft。 6 in。 in size）； the existence of which was not even
suspected whilst I was present。
On the side of the trench farthest from the buried wall （W）； the
mould varied from 9 to 14 inches in thickness； it rested on a mass
（B） 23 inches thick of blackish earth； including many large stones。
Beneath this was a thin bed of very black mould （C）； then a layer
of earth full of fragments of mortar （D）； and then another thin bed
（about 3 inches thick） （E） of very black mould； which rested on the
undisturbed subsoil （F） of firm； yellowish； argillaceous sand。 The
23…inch bed （B） was probably made ground； as this would have
brought up the floor of the room to a level with that of the
atrium。 The two thin beds of black mould at the bottom of the
trench evidently marked two former land…surfaces。 Outside the
walls of the northern room； many bones； ashes； oyster…shells；
broken pottery and an entire pot were subsequently found at a depth
of 16 inches beneath the surface。
The second trench was dug on the western or lower side of the
villa： the mould was here only 6。5 inches in thickness； and it
rested on a mass of fine earth full of stones； broken tiles and
fragments of mortar； 34 inches in thickness； beneath which was the
undisturbed sand。 Most of this earth had probably been washed down
from the upper part of the field； and the fragments of stones；
tiles； &c。； must have come from the immediately adjoining ruins。
It appears at first sight a surprising fact that this field of
light sandy soil should have been cultivated and ploughed during
many years； and that not a vestige of these buildings should have
been discovered。 No one even suspected that the remains of a Roman
villa lay hidden close beneath the surface。 But the fact is less
surprising when it is known that the field； as the bailiff
believed； had never been ploughed to a greater depth than 4 inches。
It is certain that when the land was first ploughed； the pavement
and the surrounding broken walls must have been covered by at least
4 inches of soil； for otherwise the rotten concrete floor would
have been scored by the ploughshare； the tesserae torn up； and the
tops of the old walls knocked down。
When the concrete and tesserae were first cleared over a space of
14 by 9 ft。； the floor which was coated with trodden…down earth
exhibited no signs of having been penetrated by worms； and although
the overlying fine mould closely resembled that which in many
places has certainly been accumulated by worms； yet it seemed
hardly possible that this mould could have been brought up by worms
from beneath the apparently sound floor。 It seemed also extremely
improbable that the thick walls； surrounding the room and still
united to the concrete； had been undermined by worms； and had thus
been caused to sink； being afterwards covered up by their castings。
I therefore at first concluded that all the fine mould above the
ruins had been washed down from the upper parts of the field； but
we shall soon see that this conclusion was certainly erroneous；
though much fine earth is known to be washed down from the upper
part of the field in its present ploughed state during heavy rains。
Although the concrete floor did not at first appear to have been
anywhere penetrated by worms； yet by the next morning little cakes
of the trodden…down earth had been lifted up by worms over the
mouths of seven burrows； which passed through the softer parts of
the naked concrete； or between the interstices of the tesserae。 On
the third morning twenty…five burrows were counted； and by suddenly
lifting up the little cakes of earth； four worms were seen in the
act of quickly retreating。 Two castings were thrown up during the
third night on the floor； and these were of large size。 The season
was not favourable for the full activity of worms； and the weather
had lately been hot and dry； so that most of the worms now lived at
a considerable depth。 In digging the two trenches many open
burrows and some worms were encountered at between 30 and 40 inches
beneath the surface； but at a greater depth they became rare。 One
worm； however； was cut through at 48。5； and another at 51。5 inches
beneath the surface。 A fresh humus…lined burrow was also met with
at a depth of 57 and another at 65。5 inches。 At greater depths
than this； neither burrows nor worms were seen。
As I wished to learn how many worms lived beneath the floor of the
atriuma space of about 14 by 9 feetMr。 Farrer was so kind as to
make observations for me； during the next seven weeks； by which
time the worms in the surrounding country were in full activity；
and were working near the surface。 It is very improbable that
worms should have migrated from the adjoining field into the small
space of the atrium； after the superficial mould in which they
prefer to live； had been removed。 We may therefore conclude that
the burrows and the castings which were seen here during the
ensuing seven weeks were the work of the former inhabitants of the
space。 I will now give a few extracts from Mr。 Farrer's notes。
Aug。 26th； 1877； that is； five days after the floor had been
cleared。 On the previous night there had been some heavy rain；
which washed the surface clean； and now the mouths of forty burrows
were counted。 Parts of the concrete were seen to be solid； and had
never been penetrated by worms； and here the rain…water lodged。
Sept。 5th。Tracks of worms； made during the previous night； could
be seen on the surface of the floor； and five or six vermiform
castings had been thrown up。 These were defaced。
Sept。 12th。During the last six days； the worms have not been
active； though many castings have been ejected in the neighbouring
fields； but on this day the earth was a little raised over the
mouths of the burrows； or castings were ejected； at ten fresh
points。 These were defaced。 It should be understood that when a
fresh burrow is spoken of； this generally means only that an old
burrow has been re…opened。 Mr。 Farrer was repeatedly struck with
the pertinacity with which the worms re…opened their old burrows；
even when no earth was ejected from them。 I have often observed
the same fact； and generally the mouths of the burrows are
protected by an accumulation of pebbles； sticks or leaves。 Mr。
Farrer likewise observed that the worms living beneath the floor of
the atrium often colle
