Discharging Arches.

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who know their business treat stone sills, leaving a space under the middle to be filled up at the last with mortar after the ends have got well squeezed down by the weight upon the window jambs.

Discharging Arches, as they are called, are frightfully ugly, but useful in diminishing the pressure on a long stone lintel. Over Gothic moulded arches, where our modern architects are very fond of putting them, as if the real window arch had been stuck in like a wooden frame, are totally useless, and a ridiculous and ugly display of vigorousness.' The old builders hardly ever used them. I should say 'never,' using the word in a practical common sense way; but somebody would perhaps find one or two which may have been put in for some special reason, and then make an outcry about my ignorance or boldness of assertion. Many people have not the sense to see that things which were done very rarely by the great builders of the genuine styles, were left rare because they were perceived to be not worth copying, while the good things were continually copied. Again many persons do not know that a tolerably sharp pointed arch opening hardly requires any arching at all to make it stand: much less a discharging arch besides.

Cellars and Concrete Floors.-I am told by those who are more learned in wine than I am, that cellars are best without external windows, so as to keep the temperature as uniform as possible. A friend of mine. at Buxton considers his cellar much improved in that respect by the flowing of a small stream of the famous Buxton water through it, which has the constant temperature of 84°. They should however have some internal ventilation both at the top and bottom of the door, or the air will be unwholesome.* There is a

* See the Ingoldsby Legend of The Wedding Day on this point.

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Concrete under floors.

common notion that rooms are never warm and dry unless they have cellar arches underneath; and in one sense it is true; because nobody (so far as I have seen) ever thinks of doing anything to keep the damp from rising, as it always will from the bare ground; and the more the air is warmed above it the more the damp will rise. It is wonderful that no one ever thinks of specifying that 6 inches of concrete should be laid under every ground floor. Not only that, but where the floors are not much above the natural level of the ground the best and strongest way of carrying them is to lay the joists on single bricks bedded on the concrete, or on plates or sleepers simply laid on it, instead of building 'sleeper walls' at much wider intervals; which however must be done if the floors are much above the ground, as filled in ground can hardly be depended on not to sink. I have had the floors of every building I have had to do with, from Doncaster Church downwards, made with concrete under them, and the floors laid on it where the level suited. Cellar floors cannot be made of anything better than concrete with some kind of cement, or asphalte, laid on it. Cement concrete made with sand only instead of gravel is probably the best to finish with. The best vaulting for rather wide spaces is three courses of flat tiles laid in cement, which practically form a beam and not merely a barrel vault' with a bursting pressure.

A Damp Course, made of any waterproof substance, lead, asphalte, pitch, slates laid in cement, is well-known to be necessary in order to prevent the damp from rising up the wall by capillary attraction. But it is too often omitted through carelessness or something worse. The best place for it is just below the floor timbers, to secure them from damp, as that is pretty

sure to be above the ground outside. If any room is at all below the ground the outside of the wall ought to be cemented or covered with pitch, or it will be always damp. But the most valuable protection to a house throughout from damp and cold and heat is

Hollow Walls which are now at last generally admitted to be expedient, though architects are still wonderfully slow to propose them. They seem to have been used in Italy long ago by an architect named Alberti, who was also a writer on architecture. In old times, when walls were always very thick, they were not so necessary, though even a thick wall is drier, warmer and cooler for being divided by a stratum of air. In those days two walls were generally lined with wood-panelling, and afterwards with 'stoothing' 'or battening,' which is laths for the plaister nailed on battens or strips of wood built into the wall. I happen to possess (though not to inhabit) a remarkably well built house of the last century where reeds have been used instead of laths. This process is sometimes used still, but it is not equal in some respects to hollow walls, and it does not prevent the damp coming through to the battens and rotting them in time. But architects will build you a great house with large windows' and 'paint it with vermilion,' and give you only 14 inch walls and the plaister bare upon them, and spend ten times what either stoothing or thick hollow walls would cost on good for nothing decoration, leaving you with a house not fit to live in, because the whole is damp right through in every rain, and heated and chilled through with every extreme of temperature. Any wall not stuccoed outside absorbs a vast quantity of moisture from rain, especially if it is not pointed with something more waterproof than common mortar. Pure cement will not do, as it swells

6

and cracks off, but a mixture of cement and lime and sand or brickdust will do, as we shall see under 'mortar and cement' afterwards. Stone walls are generally even more porous than brick, and are notoriously damp inside unless some other surface is interposed.

All

Hollow walls also afford peculiar facilities for ventilating rooms and floors under them without making openings outside, which are sure to be stopped up in the first very cold weather. This is particularly important in rooms where gas is burnt, and in small bedrooms and any without fire places, and it is probably a good thing in all rooms. Kitchens should have special ventilation either into or by the side of the chimney; but some air bricks,' i.e. perforated bricks so called, opening into the space between walls must be useful there also ; and there should be as many at the bottom of the house under the floors with an opening to them from the cellars, as at the top under the roof, so that there may be a general circulation of air, and none stagnant. this should be done by air bricks with small holes through them to keep rats and mice from running all over the house. The roof itself should also have some ventilation. Most roofs have plenty, through imperfect jointing of slates and tiles, but that of course is a defect. I remember once consulting the architect and surveyor to a Society about making some ventilators in the windows of a vaulted chapel with a leaded-or more accurately, a coppered roof, which is much closer than tiles or slates can be. He said he had made some ventilators himself a few years before into the roof. I answered, Yes, I know that, but what becomes of the air when it gets there?' That he had never thought of, and his idea of ventilating had been to let off the air of the chapel into this much hotter place between

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Proper thickness for them.

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the vaulting and the copper blazed on by the sun. shall have a little more to say about modes of ventilating afterwards, but this is a question of literally fundamental construction, as these air bricks should be just above the concrete inside, or just where the hollow in the walls begins. They are often put outside, right through the wall, and they are doubtless a good thing at first to dry the building; but, as I said, they are sure to be filled up in the first frost because they make the floors too cold.

The two vertical strata of a hollow wall are best connected by bits of iron tarred over (not with gas tar, for I understand that rusts iron very quickly instead of preserving it), and it is thought better even to give it a twist to prevent the wet creeping across. For the same reason the connection should not be by bricks. But solid bricks should go across at window jambs and outer doors, or they will never be decently air tight round the frames. The two walls are generally made 3" apart, but sometimes only 2": of course 3 is better. The only objection that I know is that a hollow wall is not so strong as a solid one of the same thickness, but it is easy to make them strong enough. Also you must remember that the inner wall carries all the weight of beams and floors and most of the roof, although the wall always becomes solid under the roof, or should do so. Consequently the inner wall must be the thickest, except in the single case of two 9" walls, which it is perhaps better to divide equally, though I am not quite sure of that where wooden plates' or bearers to carry the floor beams are built into the walls as usual, which reduce the brickwork of a 9′′ wall one half, and so cut it away as far as the centre of gravity.

However in a 14" wall it must be so, and nothing