_SETTING OUT THE FOUNDATIONS OF THE HOUSE, AND OPERATIONS ON THE
GROUND._
Next day a letter dated Naples was received from Madame Marie N——,
expressing the liveliest and most patriotic apprehensions with regard
to recent events. Paul’s sister wished to induce the family to join her
at Naples; her husband could not return to France just at present; the
business which called him to Constantinople allowed of no delay, and
would oblige him to embark very shortly. The letter terminated thus:
“We have received Paul’s designs; we suppose his cousin must have given
him a little help. I should be delighted, and my husband too, if there
was any chance of such a plan being realized; but who can think of
building in the state in which our poor country is now! Rather make up
your mind to come and join us.”
“Well,” said M. de Gandelau after reading the letter, “you see your
plans are approved: let us set to work at once. If the Prussians should
come as far as this and set our old house on fire, as their custom is,
they will not burn the walls of a building only just begun, and what we
have spent in its erection will not get into their pockets.”
Eugène, helped by Paul, who calculated the items—he had never
undertaken such a task before—drew up the estimate, which amounted
in all to 7,000_l._ The earthworks and masonry were expected to cost
3,400_l._
Master Branchu was summoned: “A very good gentleman your father
is,” said he to Paul, when it was settled that they should begin
the following day; “he sets people to work when the best hands are
being turned off everywhere, and old fellows like me, who cannot go
soldiering, would have a hard time of it all the winter. I shall go and
drink his health with Jean Godard the carpenter, who will be desperate
glad like myself.”
The rest of the day was employed in marking the principal dimensions on
the plan, so as to be able to set out the excavations.
Master Branchu was already on the ground next day, equipped with
lines, stakes, nails, and _broches_, a large carpenter’s square, and a
water-level, when Paul and his cousin arrived at an early hour in the
morning.
“You see,” said Eugène to Paul, “that the figures indicate on this plan
the distances between the centre-lines of the walls. Consulting these
dimensions, we shall set out these centre-lines on the ground with
the help of lines attached to what we call _broches_ (Fig. 19), which
consist of two stakes firmly fixed in the earth, and a crosspiece. The
direction of one of the centre-lines being determined according to the
orientation it suits us to choose, the places of the other axes will
follow according to the distance figured on the plan and the square
returns.”
Eugène had soon settled the line of centre, A, for the dining and
billiard-rooms, according to the desired orientation. Then on this
first centre-line was set out by means of a small theodolite another
at right angles, which was the centre-line of the entrance-hall. These
two lines once laid down, the others were determined by means of the
dimensions previously marked on the plan. The centres of the principal
walls were thus traced on the ground by lines attached to the _broches_.
[Illustration: FIG. 19.]
As cellars were to be made under the whole extent of the main
building, Eugène contented himself with ordering Branchu to excavate
the entire ground to a distance of about a yard beyond the lines of
the perimeter. Two labourers with their picks set to work therefore at
once to mark out the excavation. “If,” said he to the workmen, “you
find stone, as may certainly be expected, at no great depth, and if it
should prove to be of good quality, you will take care not to break it
up; get it out for walling stone; we will make use of it and pay you
for your extra trouble. If you find boulders, let them be blasted, and
lay aside the best pieces for use. To-morrow or the next day we shall
give you the plan and section of the cellars. Meantime lay in a good
store of bricks, lime, and sand; you know that in this district it is
desirable to arrange matters beforehand if we would have the materials
when wanted. It is September already, and our cellars must be built at
least before the first frosts.”
“This being settled then,” added Eugène, addressing Paul when they were
returning to the house, “I appoint you clerk of the works, and these
will be your duties: You will come to the ground every morning, and
take care in the first place that the orders given in your presence
are strictly executed. For instance, you will have to take account
of the quantity of stone extracted from the excavation, and to have
it properly stacked in a heap about one yard thick, two yards broad,
and of a length depending on the yield of the quarry. Having thus
verified the daily increase of the heap, we shall be secure against
any abstraction from it. You will keep a note-book in your pocket, in
which you will mark its daily augmentation, and you will take care
to have every leaf countersigned by Branchu. Your business just now
will be only overlooking; but it will become more complicated as the
works advance. If materials are brought you will take account of the
quantity,—in numbers if it is bricks, or by solid content if it is sand
or lime. For this purpose I shall have brought to the ground one of
those road-labourer’s boxes, which are a yard square and half a yard
deep. Each measure when filled contains therefore half a cubic yard.
“You will tell Branchu to get a wooden shed built to keep his tools
in, and to keep the lime under cover till it is slacked. If we had
a contractor, or some one with whom a bargain had been made, we
should not have to trouble ourselves about the quantity or content
of the materials brought to the ground; but as it is, we must employ
elementary means, for Branchu has not capital with which to provide
materials. We shall therefore give him the materials we buy, or
which the estate supplies, on account. You perceive the necessity of
preventing these materials from being abstracted or wasted. We pay
him only for the labour. This plan obliges us to be more attentive
and vigilant, but we are at least secured from being deceived as to
the quality of the materials by a contractor, who might think it his
interest, if he bought them, to supply us with some of a quality
inferior to that contemplated in the estimate.
“We shall make the same terms with the carpenter. Your father tells me
he has some oak timbers that have been cut more than two years, and put
in the wood-yard near the Noiret farm. Let us go and have a look at
them, and mark those that can be employed. Our figured plan gives us
the lengths of the flooring joists.”
Passing by the side of the rivulet that flows along the little valley,
Eugène was looking attentively at its steep banks, and was striking the
rock faces with the iron-shod end of his stick. “What do you observe
there?” said Paul.
“I think we shall find here good materials for our cellar vaulting....
Look at this yellowish stone, porous like a sponge. It is a present
to us from this little water-course. It brings down in its waters
carbonate of lime, which is incessantly being deposited on the grasses
and vegetable detritus on its banks and in its bed. This rivulet thus
forms a light and very porous tufa, which is soft and friable as long
as it is thoroughly moist, but which acquires a certain degree of
hardness in drying. Formerly this rivulet was larger than it is now,
and it appears to me to have deposited a considerable thickness of
this tufa as presented on its banks in their actual condition. Take
this bit, and look at it attentively. You see that it is filled with
cavities,—little cylindrical passages; they represent the twigs around
which carbonate of lime was deposited. The twigs themselves decayed and
disappeared long ago; the coating has remained and been hardened in the
air. Observe how light this kind of stone is, being composed of cells
scarcely thicker than egg-shells. Yet, try to crush it under your heel.
It resists, and the pressure scarcely blunts its asperities. Well, dry
it, and in a week it will be even harder. A smart blow with a hammer
will be required to break it.
“This material is perhaps the best for vaults, on account of its
lightness, its toughness, its cavities, and that roughness of surface
which makes the mortar adhere so closely to the joints that it cannot
be separated, and the whole, when sufficiently dry, seems to form only
a single piece.
“We shall send two excavators to get out a few cubic yards of it. It is
no difficult operation; and when this tufa is in a damp state in its
natural bed, it can be very readily cut up into brick-shaped pieces.”
They soon reached the Noiret farm; and there in fact, under a shed
along the wall of the barn, were piled up pieces of timber roughly
squared and blackened by damp. Eugène marked a certain number of
them with his knife, leaving those that were crooked, knotty, or
cross-grained.
“What is a cross-grained piece of timber?” asked Paul.
“Cross-grained timbers are those whose fibres form a spiral round
the heart. You can understand how the fibres of the wood not being
vertical, and forming spirals more or less complete, lose their
resisting property; these fibres, on account of the circuit they
make,—and which is not a regular one,—become disjoined, and leave
deep cracks between them. These timbers, therefore, are rejected as
defective, as are also those whose heart is unsound, or which have
what they call soft rings; that is, diseased parts between their
layers—a sort of interior ulcers which not only deprive the wood of
its homogeneity of resistance but develop decay around them. It often
happens that these soft rings are not observed, and that timbers which
appear very sound fall rapidly to dust. And as these diseases are
frequent or rare according to the soils in which the wood grew, it is
essential to know whence the timbers employed in buildings came. One
forest will produce oak admirable in appearance, but which rapidly
decays; another furnishes timber that is always sound. Generally,
timber grown on light and dry soils is good; the produce of damp,
clayey ground is bad.
“You will have these cross-grained and crooked timbers put on one side;
they will do to make the centres for the cellars; they are fit for
nothing else, unless it be for firewood. As to these fir poles, they
will serve for scaffolding.”
It was late, so the cousins asked for breakfast at the farm. While
they were laying the table, Paul said, “I want to know how you use the
theodolite.”
[Illustration: FIG. 20.]
“In the case of an operation such as we have just been performing,
it is the simplest thing in the world. I asked Branchu to send my
instrument to the _château_, that I might not be troubled with it
all the morning; but there is no need to have it here to show how to
use it. You know that the theodolite consists of a graduated circle,
divided into 360 degrees. This circle, movable on its centre, is
furnished with an air-bubble level, and a telescope above, both of
which turn horizontally on a pivot in the centre of the circle. The
level and the centre of the telescope are perfectly parallel to the
plane of the circle. This is placed upon a stand with three legs, and
the circle is first fixed horizontally by means of three regulating
screws, and by turning the level. The air-bubble must be always at
the centre, to whatever degree of the circle the tube is directed.
This being done, and the feet being placed at the point marked on the
ground—verifying the position by means of a plumb-line passing through
the centre of the plate—the glass is directed towards a fixed point
where a ‘sight’ is placed. The glass of the telescope is crossed by two
hairs at right angles, which mark its centre. The intersection of the
two hairs must fall on the point on which the telescope is directed.
But previously the indicator or vernier below the telescope is set to
the zero of the circle. It is therefore the entire instrument that
has been turned. If, then, for example, we wish to construct a right
angle on the line joining the point where you are standing with the
first sight, you turn the glass till its indicator stands at 90 degrees
(the quarter of the circle). You send a man with another sight in the
direction of the glass, and have this sight carried to right or left
until its centre is exactly on the line of the vertical hair of the
glass. You have this sight fixed. It is then certain that the line
drawn from the point where you stand in the direction of the second
sight forms a right angle with the first base line, since two diameters
cutting a circle divided into 360 degrees at right angles give 90
degrees for each quarter of the circle. By the help of this instrument,
having previously indicated on the plan of a building whose foundations
you are laying out, the angles which certain lines, starting from any
point, form with each other, you can transfer these angles to the
ground. Suppose you have to lay the foundations of a semi-circular
portico. Having fixed the centre, and traced the semi-circle on the
ground, placing the theodolite on this centre, you will be able to
direct lines that will cut this circumference at regular intervals, and
which would mark, for instance, the centres of the columns or pillars.
Since from point A to point B you have 180 degrees (Fig. 20), you
will divide these 180 degrees into as many parts as you choose on the
circle of the theodolite, and the centre of the glass will give you,
at a great distance, the same divisions on the semi-circular portico.
In the same way as the theodolite serves the purpose of laying the
foundations of a building, it enables us to take the bearings of a
tract of country. For suppose the base, E F, to be a known length which
you have measured: placing your instrument at E, you direct the glass
on a point C,—a tree, a steeple, or a pole; you have then the number
of degrees on the circle comprised by the angle C E F. You transfer
this angle to your paper, then moving the instrument to the point F,
you direct it thence on this same point C; you obtain similarly the
angle C F E, which, transferred to the paper, gives you exactly the
position of the point C, and the unknown distance from E to C and from
F to C; then either of these lengths will serve you for a base in its
turn, and operating from the point C and the point F, and sighting a
fourth point D, you know the lengths C D and F D. Thus you can operate
over a whole country; this is what is called _triangulation_, the first
operation required for getting a map of the country. But we are getting
into another region of knowledge. Let us go to breakfast!”