Fig. 26.
This drawing presented, in section at A, and in plan at B, the figure 26. Eugène had to explain this sketch to his clerk-of-works, who did not understand it at the first glance. “As the light comes from the sky, at the mean angle of 45°, the cellars must be lighted accordingly,” said Eugène. “The plinth consists of a course, D, half sunk in the ground, two clear courses, E F, and a course bearing the set-off. We give the cellar wall bearing the spring of the vaults, 3 feet. The wall above the floor-level being 2 feet, this wall gives one foot on each side of the fixed centre-line, but as the plinth has 4 inches of projection outside, there will be 16 inches from the centre to the exterior face of this plinth. Within, the wall descends plumb as far as the skew-back which carries the vaults. A width of 8 inches is needed to receive the latter. Thus, from the centre-line below the spring of the vaults there will be 20 inches in the interior, and 16 inches on the exterior: total, 3 feet. The lower course rising above the surface 6 inches, and the height of the plinth being 5 feet, there remains above these 6 inches, 4 feet 6 inches, which divided by three gives for each course 18 inches. I take the opening of the air-hole in the second course; out of the third, I take a chamfer of 4 inches, to admit the light, as the exterior, M, and the section indicate. I cut the first course to a slope of 45°, as shown at I, leaving a flat, a, of 12 inches, as you see in the plan. Then, behind this sill, I place a lintel, with a chamfer in the same way, as drawn at O, and take care to leave at b, two rebates of 2 inches, for casements or gratings, at discretion. At the back of these rebates, I splay the air-hole, which has only 2 feet 8 inches of exterior opening, to 3 feet 4 inches. I draw in section an inclined line, m n, 8 inches above the lintel O, which 8 inches will be the rise of the arched opening that will penetrate into the barrel-vault, and whose curve in horizontal projection will give the outline X. Thus this arch, X, will receive the thrust of the courses of the barrel-vault, and will throw it on the two cheeks, P. Branchu will only have to mark the curve X on the covering of the centres to form his arched opening.”
Fig. 27.
It was not quite certain that Paul perfectly caught this explanation, though repeated several times; and he did not understand it completely till he saw Branchu construct the air-holes and the centres were removed (Fig. [27]).
Fig. 28.
“I spare you the difficulties,” said Eugène, seeing that Paul was puzzled to comprehend the construction of the cellars, “for the structure of the vaults and their penetrations is a matter that requires long study. We have made only simple barrel-vaults, and you will observe that the cellar doors are all in the end walls, or tympanums, and not in the side walls bearing the springing of the vaults. With the difficulties, I also avoid useless expense. The courses which form the plinth will be of hard stone, but you will observe that, except at the angles and for the air-holes, they are only a facing,—they are not parpings, that is, do not form the whole thickness of the wall. We have excellent rubble-stone, which, with the good mortar we employ, offers greater resistance to pressure than is required to carry two stories and a roof. Letting these rough stones tooth out on the inside we tie them better into the haunches of the barrel-vaults (Fig. [28]), and thus economise dressed stone. You will also see in elevation, above the plinth, how we can spare dressed stone if we wish, while preserving a perfectly sound construction. We find moreover, on the surrounding uplands, layers of thin limestone, which split in regular beds from 6 to 8 inches in thickness, and which make capital range-work. We call that range, or coursed work, in which the stone is laid with visible faces, beds, and joints somewhat roughly dressed. This range-work facing, which presents in its way an attractive appearance, and whose rusticity contrasts with the smooth finish of the dressed stone, is backed with ordinary rubble walling. Thus, in districts where stone occurs naturally of this shape in the quarries, we get an economical building material. But it is puerile to amuse one’s self with making thin coursed-work where soft freestone abounds, and where it must be cut into little bits to obtain this appearance. You will see that it is contrary to common sense to cut great blocks of stone into little bits, and that when the quarries supply those only, it is reasonable to employ them according to their natural dimensions, and to adapt the construction to the nature and height of the stones. Here we have large blocks, when we require them, but they are not common. In short, we ought to proceed, as far as possible, according to the nature of the materials which the soil furnishes us in abundance.”
The drain was made, the vaults were turned; the steps down to the cellars were laid; the plinth had risen more than a yard above the ground. It was time to think about studying the details of the elevations. That overlooking the garden was only roughly sketched out. Paul was hoping that it would present a more regular appearance than that of the entrance side. He made a remark to that effect, for Paul had seen in the environs of Paris, many country-houses that seemed to him charming, with their four pepper-boxes at the angles, their porch in the very centre of the façade, and their zinc cresting on the roof. He had too high an opinion of his cousin’s ability to allow himself to criticise the façade of his sister’s house, as designed for the entrance side; but in his heart he would have preferred something more conformable to the laws of symmetry. Those windows of all forms and dimensions shocked his taste a little. When the façade on the garden side (Fig. [29]) was sketched—a frontage which, this time, presented a symmetrical aspect—Paul declared himself satisfied with it; and in the evening, the family being assembled, he asked why the entrance front did not present the symmetrical arrangements which delighted him on the garden side.