_PAUL, CLERK OF THE WORKS._
“Go, my dear Paul, and see how far the excavations are advanced this
morning,” said Eugène, two days after the visit to the ground, “and
bring me your report. Take a rule and a note-book with you, and take
notes and measurements of what has been done. You will examine the
ground, and tell me if they find blocks of stone near the surface of
the soil, or if the loose earth is deep. In the meantime I am going to
draw the plan of the cellars. But take the tracing of the plan of the
ground-floor of the house, and on this plan, mark out what they have
begun to excavate, and what they find. The work cannot be far advanced;
but some excavations will have been already made, since I have told
Branchu to set as many labourers to work as he could find, so as to
comply with your father’s intentions.”
A little embarrassed by his new duties, Paul soon reached the ground.
Aided by Branchu, he took the measure of the diggings, indicated the
depths as well as he could, and marked the spots where they found rock
or loose earth. This took him two good hours.
“Well,” said Eugène, when they were settled in the study, after
breakfast, “there is the plan of the cellars (Fig. 21). Let us see
how it will suit your report of the ground, and whether we shall have
to make some modifications in this plan. Ah! I see the rock is nearly
on the surface towards the south, and the loose soil reaches pretty
uniformly a depth of three yards towards the north of our buildings.
We shall, therefore, make the cellars under the drawing-room, the
dining-room, and the billiard-room, in the limestone rock,—cutting the
latter; and we shall make a foundation for the front part, especially
for the stabling and coach-house, with good masonry.
[Illustration: FIG. 21.]
“Here (Fig. 21) is the plan of the cellars. You see these axial lines:
they indicate the centres of the walls of the ground-floor, and must
not be departed from. The figures denoting the thickness of the walls
are always marked from these centres. Thus you see these dimensions
are greater where the cellar-wall will have to carry the spring of the
vaulting of the cellars—as I explained to you, the other day.
“We have a rivulet that will supply the services of the house, by means
of a reservoir, which we will place as high as possible. We have not
yet taken the levels; but judging by a glance, I should say (reckoning
by the falls of the rivulet and the rapidity of its course) that at
100 yards from the house the reservoir will store the water so as to
enable it to reach the level of the first floor by pipes. That we shall
have to ascertain. Otherwise we shall have recourse to a pump worked by
horse-power or by a windmill. We will afterwards conduct this stream of
water into a drain along the walls at the north of the house, as you
see at A, so that this drain may collect the waste water from the house
by a conduit, B, and receive the closet discharges at C, D, and E. The
running water will thus take off this sewage into a tank, which we will
make down below in the kitchen-garden. This water when it has settled
is excellent—let me tell you—for watering the vegetables.
“I have indicated on the plan at G the sections of the cellar
barrel-vaults. The cellars will measure 5 feet from the floor to the
spring of the vaults, and the vaults will have a rise of 5 feet. These
cellars, therefore, will have a height of 10 feet under the crown,
which will be very satisfactory, especially as the ground is dry. We
shall then be able to make use of the cellars, not only for storing
wines but vegetables, for a larder, &c. The level of our ground-floor
being 5 feet above the general surface of the ground, we shall easily
ventilate these cellars by air-holes, as I have marked at H. The
descent to them will be by the steps on the right, situated near the
wash-houses and by the servants’ stairs in the turret. The right-hand
steps will serve for taking down stores, and the winding-stairs for
carrying up the wines and other things to the pantry.
“Have you seen whether Branchu has taken care to have the materials
extracted from the excavations regularly deposited?”
“Yes: but hitherto he has found only thin layers of what he calls
rag; but he has them stacked, and tells me they will be very good for
foundation walls.”
“He is right: this rag is liable to injury from frost in the open air,
but it is hard, and does very well in cellars; and it makes good strong
walling, because it is bedded,—that is, occurs in the natural state in
thin parallel layers, 4 to 6 inches thick.”
“That is just about what he told me; but he added that it _swallows up_
a great deal of mortar, and I did not quite understand what he meant by
that.”
“The fact is this;—the thinner the layers of stone are, the more beds
of mortar they require between them; but if you have observed the thin
stones in question you will have remarked that they are extremely rough
and riddled, with cavities on their beds. There must be plenty of
mortar between each course, to fill these rugosities and cavities well:
and for that very reason masonry of this kind is excellent, if you are
not sparing of mortar; and these rough surfaces adhere to the mortar
much better than smooth surfaces could do: they become incorporated
with it, and the whole soon forms one solid mass. But then you must not
spare lime and sand, and that is why Branchu says this kind of walling
swallows up a great deal of mortar.”
“Branchu also says that he has been finding stone good for making lime,
above blocks of building limestone, and asks whether he is to put that
aside.”
“Certainly if the lime-burner at the Mill cannot furnish us with lime,
we will make it ourselves; this will not be difficult since we have
plenty of firewood from the recent fellings.”
“Branchu also asked me where he was to put the excavated earth.”
“You will tell him to-morrow morning, to have it deposited _en
cavalier_ to the right and left of the excavations; we shall want it to
level the approaches to the house.”
“What is a _cavalier_?”
[Illustration: FIG. 22.]
“It is an artificial mound of regular breadth and height, so that its
solid content can easily be calculated. Thus, when earth is removed
from diggings with wheelbarrows,—and this is, as you see, the means
we are employing,—we mark out the area this mound is to occupy on
the ground, as at A B (Fig. 22), representing the length, and C D
the breadth. That done, the point B being farthest from where the
excavation is going on, the wheelbarrow men deposit their first loads
at B, leaving an inclined embankment not too steep for the barrows
to be wheeled up it without too much labour. Thus by degrees an
embankment, A E B, is formed. Then, from the middle F half way up the
incline A E, they leave a road, _a b_, 5 feet wide for the barrows
to go up and down, and then fill up the triangle, A G F, by inclined
layers. Lastly, they fill the triangle, G F E. The road, _g_ D _h i_,
remains to be filled up, and the shovellers do this by depositing the
soil on the road itself. The mound being thus perfectly regular, its
slopes are produced by the running down of the soil—that is, they form
angles of about 40° with the horizon, according to the nature of the
embankment. The mound being finished, and measuring, say, 10 yards long
at half its length from _l_ to _m_, and 4 yards wide at half its height
from _n_ to _b_,—multiplying 10 yards by 4 yards we get 40 superficial
yards at this mean level. Multiplying this number by 2 yards, the
height of the mound, we get 80 cubic yards. You know therefore that
this quantity of earth has been moved, and consequently, what you have
to pay, if your cuttings and embankings are at so much per cubic yard,
or what a cubic yard of soil removed costs you if you pay by the day.”
“This will give us the solid content of the excavation then?”
“Not exactly. Earth compressed,—settled down in the natural
soil,—occupies a smaller volume than that which, having been moved,
leaves many interspaces between the materials of the embankment. Soil
when removed is said to _increase_, more or less. Sea-sand does not
increase, while pebbly earth, mixed with vegetable detritus, increases
greatly. In your memoranda, therefore, you must take account of the
looseness caused by excavating, to get the solid content of the soil
removed; and take the solid content of the mounds when we make use of
them, to know the mass of earth we shall have to transport elsewhere.”
“You will now draw this plan of the cellars to a scale of a quarter of
an inch to a foot, so that you may figure the dimensions very legibly
where required; then I shall indicate to you on this plan the points
where bedded stone must be placed.”
“What are bedded stones?”
“Dressed stone laid as a foundation is thus designated, and which is
only dressed on its beds,—that is to say, which presents no visible
faces. Dressed stone has always two beds, which are its horizontal
surfaces, one or more faces, which are its exposed surfaces, and its
joints, which are its separating surfaces. Thus, let us suppose a
corner stone, bearing a pilaster, and having the form indicated here
(Fig. 23), the surface _a b c d e f_, _g h i j k l_ are the upper and
lower beds. The surfaces _a l b g_, _b g c h_, _c d h i_, _d e i j_
are the exposed faces, and the surfaces _c f j k_, _a f k l_ are the
joints, as the adjacent stones touch these surfaces. You will easily
see that when stones are placed below the surface, as a foundation,
it is not necessary to dress the faces which would be visible only
to the moles. This cutting therefore is saved; the stone is left in
the rough on its vertical faces, and only those on which it rests are
cut. For these bedded stones solid blocks are chosen, which sustain
pressure, but which may be very coarse in grain, and even sensible to
frost (_i.e._, liable to be cracked by frost), and which could not be
employed in the open air without danger; under ground these stones are
preserved from the action of frost. But care must be taken with regard
to these stones even more than for those above ground, to place them
according to their quarry-bed, and their natural stratified position;
otherwise they might be broken or crushed beneath the weight of the
masonry above.
[Illustration: FIG. 23.]
“When our plan is drawn, we shall indicate by a particular colour
the parts where we wish bedded stones to be placed. These will be
the angles and the junctions of the walls which sustain the heaviest
pressure relatively to the rest. Between these bedded stones the
masonry will be carried up simply in rubble-work.
“The ground being good, we shall content ourselves with foundations
only half a yard below the area of the cellars. But as soon as we have
reached this level, the dressed stones will necessarily have faces
visible in the cellars; these stones will therefore not merely be
bedded, but faced and jointed. We will not take the best and finest
grained, but those that resist pressure best, and which in this
district are the coarsest in appearance. We shall put dressed stones in
our cellars at the angles, the jambs of the doors and air-holes, and in
the newels of the stairs.
“But you have enough work for to-day and to-morrow morning.... Ah! I
was forgetting! If Branchu meets springs, or drippings, that trouble
him, inform me, because we must immediately make drains to collect the
water. That will determine us as to the level to be given to the bed of
our sewer.”
“What do you mean by the bed?”
“It is the part of a channel sluice or a sewer on which the water
flows; it is the bottom, which ought to be formed so solidly that the
force of the current cannot disturb it. The beds of sewers, therefore,
should be made of good flat stones, or, which is still better, of
hydraulic cement, when it can be procured, because the water finds its
way between the joints of the stones; while, if the cement is properly
used, it forms along the whole channel one homogeneous mass perfectly
water-tight. Besides we take care to give to the bed of a drain a
section slightly concave, joining its walls without angles; for water
takes advantage of angles to effect its work of destruction. Angles,
moreover, are not easily cleared out when subterranean channels have to
be cleansed. The best form to give to a sewer is the one given here in
section (Fig. 24).
[Illustration: FIG. 24.]