Chapter II: Part 2

"The material when placed in water fell to pieces. On analysis, it was found to consist of:

Per cent.
Stones (residue on 7 by 7 mesh sieve) 24.40
Sand, coarse (residue on 50 by 50 mesh sieve) 19.70
Fine sand (through 50 by 50 mesh sieve) 32.50
Clay 20.60
Straw 1.25
Water, etc. 1.55
------
100.00
------

"The material is a conglomerate of slaty gravel with a very sandy clay, to which mixture a small proportion of straw has been added.

"The clay acts as an agglutinant, and the straw as a reinforcement.

"Efficient protection from frost and rain would be necessary before such material could be considered weatherproof."

* * *

(N.B.--Lime is occasionally added to the clay-shale, but this is not usual.)

_Mixing._--The old method of mixing by hand is as follows: A "bed" of clay-shale is formed close to the wall where it is to be used, sufficient to do one perch. A perch is superficial measurement described as 16-1/2 ft. long, 1 ft. high, and the amount of material will vary according to the thickness of wall required. Four men usually work together. The big stones are picked out. The material is arranged in a circular heap about 5 or 6 ft. in diameter.

Starting at the edge the men turn over the material with cob picks, standing and treading on the material all the time. One man sprinkles on water, and another sprinkles on barley straw from a wisp held under his left arm. The heap is then turned over again in the other direction, treading continuing all the time. "Twice turning" is usually considered sufficient. Straw bands may be wrapped puttee-wise around the legs of the men to keep them clean, and these are removed at the end of the day.

More rarely the mixing is done in a rough trough, whilst a power-driven "pan-mill" has also been tried with success; though one would think that the use of such a machine might tend to diminish the binding strength of the straw submitted to its grinding.

[Headnote: Implements]

_Building._--In building a man stands on the low base-wall, and lays the material handed up to him on the cob picks, treading it into position. Thorough treading is important, and the heels should be well used. The material is allowed to project each side an inch or so beyond the stone base to allow for paring down afterwards. The courses are usually about 2 ft. high. The cob should be laid and trodden in diagonal layers, as shown in the diagram: this is to secure proper bonding. It takes from two to three weeks for a course to dry, according to the weather, and five or six men would be required to build the walls of an ordinary cottage. This would not keep them continuously employed, however, and they would require to have several buildings in hand at the same time, so as to be able to turn from one to the other while the courses were drying.

At the completion of a course the corners are plumbed up from the stone base below, a line is stretched through and the wall is then pared down "plumb" with the "paring iron" by the man standing on the wall. Sometimes, however, the paring down is left until the wall is finished and dry. Four men will do about four perches per day of a wall 2 ft. thick, preparing and laying material.

The material is rarely laid between timber shuttering as in Pise work, as the retaining boards tend seriously to retard the drying out.

_Drying._--If a course takes from two to three weeks to dry, it naturally takes a long time for a whole cottage to completely dry out. The walls can be built from about March to September. The internal fitting, plastering, etc., can be done in the winter, but the external rendering must not be done for at least a year, perhaps two years, to allow the walls to become perfectly dry.

As unprotected cob is sensitive to frost, especially if not thoroughly dried out, it should be given a good external rendering as soon as it is really dry, and should in the meantime be protected from frost by some temporary covering, straw-matting or what not. Also all cob-work must be protected from the rain both whilst building and when built.

No artificial methods of drying are at present usual, beyond good fires inside during the winter, though, as under such conditions a cob cottage is not usually considered fit to live in for several months after completion, some artificial means of drying might be worth considering.

_Foundations and Base._--The depth of the excavations required for the foundations naturally depends upon the character of the site and soil, as also does the spread of the footings, if any.

The base-course wall of brick, stone, or concrete should be carried up some 2 ft. or so above ground level. In old days this walling was not infrequently built "dry"--but good lias lime or cement should be used in all new work.

The damp-course too was an unknown refinement to the by-gone builders, and the introduction of this one improvement alone makes the new cob cottage a very different dwelling from the old.

The usual forms of damp-course serve well for cob walls, though slates laid butt and broken joint in cement are probably the best.

[Headnote: Walls and Roofs]

_Thickness of Walls._--The thickness of walls may be anything you please from 18 in. upwards. There are old examples a full 3 ft. across, but for an ordinary two-storied cottage a thickness of about 2 ft. is general. Eighteen inches is certainly the minimum thickness, and would not ordinarily be adopted for any but one-storied buildings.

The first-floor walls are made the same thickness as those below, for if they were reduced in width, as is usual in a stone building, the extra weight thus thrown on to one side of the ground floor walls would tend to make them bulge, unless quite dry and thoroughly set.

There are old cob walls in existence fully 30 ft. in height, and there is no apparent limit in this direction provided they are thick enough.

The upper layers compress the lower ones, and automatically render them more dense and stone-like and fit to bear the load imposed above.

_Hipped Roofs._--As a general rule, however, it is found expedient to hip back the roof rather than carry it up in a tall gable, partly because cob-building at a great height above the ground in short and diminishing layers is a somewhat tedious process, partly because a hipped roof with good eaves is very welcome for the protection that its projection affords the walling.

_Masonry and Carpentry._--The bonding of cob to stone and brick is sometimes liable to leave an open joint that will require filling when the cob dries and shrinks. Many of the chimneys in old cob houses are of brick or stone, and brick and stone jambs are sometimes to be seen in cob walls, but they are probably by way of repairs to damaged corners. It is considered better to have cob all round, so ensuring the uniform settlement of the building.

The timber built into old cob does not seem to decay. The walls are usually so dry, especially when plastered, that the wood is well preserved. The straw in the interior of old cob walls is often as bright as when put in. The straw in cob performs a similar function to hair in plaster. Heather has sometimes been used instead of straw with good results.

The old practice was for beams, wall plates, joists, etc., to be just bedded on the cob, and for the cob to be filled in between the joists. In new work, particularly when the use of imperfectly seasoned timber is unavoidable, it would be wise to take the usual precautions as to the proper ventilation of all "built in" woodwork--especially the ends of joists and so forth. Roofs must of course be tied and exercise no thrust on walls. The roof plates are sometimes tied down by galvanised iron wire.

Door and window-frames are also fixed to wood blocks built into the jambs and to the wood lintels above. The frames are sometimes near the outer face of wall, sometimes near the inner-face. Where the door-frames are on the interior face of a 2 ft. thick wall, a convenient porch results.

Other joinery is fixed to wood pins driven into the cob where required.

Corners are usually of cob, though stone quoins are occasionally met with.

Lintels are usually of wood well tailed into the wall and resting on a wood pad placed crosswise.

[Headnote: Protection]

_Protection._--Old buildings that have been neglected are often found to be somewhat eroded towards the bottom of their walls through the action of rain and frost.

Protection is less here than higher up under the projecting eaves, and the Achilles' heel of the cob wall is undoubtedly its base.

This vulnerable part, exposed as it is to driven rain, back-splash, and the casual kicks, should be given special protection.

Where the base is of cob and not of masonry, the traditional method is to provide a good deep skirting of pitch or tar, or a mixture of both, applied hot to the face of the rendering that should completely cover the exterior of all cob work.

This rendering is usually composed of lime and hair mortar, though Portland cement has come into use to some extent recently.

Cement, however, is apt to be rather too "short" and brittle, and it does not always hold to the cob walling very securely.

A rendering consisting of an equal mixture of cement and lime with three parts of sand adheres well to cob, however, and is probably the best coating that can be given to it.

This coating can be colour-washed or lime-whited in the usual way. The granular surface of rough rendering or of "slap-dash" on the slightly wavy surface of cob walling perhaps gives to whitewash its very highest opportunity and charm.

Certain it is that the old cob cottages of Devon with the pearly gleam of their white walls, their heaving bulk of thatch and their trim black skirtings, are as gracious and as pleasant to the eye as any in all the length and breadth of England.

Within, lime-and-hair mortar plastered straight on to the cob makes an excellent lining.

_Chimneys._--Nowadays, chimneys are commonly built up in brick or stone, but numerous good examples survive of flues and stacks constructed in cob. The insides of these are pargeted with lime and cow-dung in the usual way, brickwork being only introduced immediately around the fireplaces.

_Rats._--Where the surface rendering of cob-walls has been omitted or has been allowed to fall away, an enterprising rat will sometimes do considerable damage by his tunnelling.

A little powdered glass mixed with the lower strata of a wall will discourage any such burrowing, but the best preservative for any cob building is a thoroughly good skin of rendering, especially if this be reinforced by fine-mesh wire-netting secured to the wall.

_Strength._--The strength of cob walls is surprisingly great so long as they are vertical, and are not subjected to undue lateral thrust or tension.

Beams as large as 12 in. by 12 in. may be seen supported by old cob walls, and there is nothing likely to be asked of the material in the way of strength to which it cannot easily respond.

_Design._--Cob, like every other material, should have a certain say in the design of any building in which its use is intended.

The chief desiderata are a plain straightforward plan and broadly treated elevations where voids and solids are carefully disposed with an eye to getting as large unbroken blocks of cob as possible.

The cracks that are sometimes found in old cob buildings are almost entirely attributable to unsuitable design in such respects, or to bad foundations.

Cob walls built up in the ordinary way are not very suitable for internal partitions on account of their considerable width and the consequent waste of space, though in old work cob was sometimes used as a filling for stud and lath partitions which were finally plastered over in the usual way.

The sun-dried clay-lumps so much used for walling in Suffolk would seem to be admirable for forming the partitions in a house of cob.

Cob work is usually repaired with rubble, stone, or brick.

New openings are easily cut through cob walls, and this fact has occasionally led to the collapse of an old building through the zeal for light and air of some new occupier exceeding his caution, and causing him to cut away the substance of his walls in cheerful disregard of the laws of gravity.

Sec. III. CONCLUSION

AUTHORITIES--ANCIENT AND MODERN

Not by any means was cob exclusively the poor man's material, and several old homes of this sort still survive that are of some consideration.

[Headnote: Raleigh's House]

Amongst them is Hayes Barton, the birthplace of Sir Walter Raleigh. Writing of Raleigh and his home, Mr. Charles Bernard says:

* * *

_Sir Walter Raleigh's House._--"He had great affection for his boyhood's home--the old manor-house at Hayes Barton where he was born, and did his best to secure it from its then owner. 'I will,' he wrote, 'most willingly give you whatsoever in your conscience you shall deme it worth . . . for ye naturall disposition I have to that place, being borne in that house, I had rather see myself there than anywhere else.' But alas! it was not to be, and the snug and friendly Tudor homestead passed into other hands. The house at Hayes Barton was probably not newly built when Raleigh's parents lived there, and it says much for the character of cob that the house is as good to-day as ever it was; though for all that it has, to use Mr. Eden Phillpotts' words, 'been patched and tinkered through the centuries,' it 'still endures, complete and sturdy, in harmony of old design, with unspoiled dignity from a far past.' Lady Rosalind Northcote gives the following description of the house in her _Devon_. She writes: "In front of the garden, a swirling stream crosses a strip of green; and in the garden, at the right time, one may see the bees busy among golden-powdered clusters of candytuft, and dark red gillyflowers, and a few flame rose-coloured tulips, proud and erect. The house is very picturesque; it has cob walls and a thatched roof, and is built in the shape of the letter +E+; a wing projects at either end, and in the middle the porch juts out slightly. The two wings are gabled; there is a small gable over the porch and two dormer ones over the windows at each side of it, the windows having lattice lights and narrow mullions. Dark carved beams above them show up well against the cream-coloured walls. The heavy door is closely studded with nails, and over it fall the delicate sprays and lilac "butterfly" blossoms of wistaria.'"

_Reed Thatch._--In recent years slates or tiles have replaced thatch for the roofing of cob buildings and walls, owing to the cost of reed (the local name for the straw from which the grain has been hand-threshed by flail to prevent the straw being broken), and the difficulty of getting good thatchers. The opinion is held by many that the lasting quality of thatch has deteriorated since the practice of liming the cornland has unfortunately been given up.

_Primitive Methods._--Formerly the ground floors of cob cottages were all cobbled, but these have, generally speaking, been replaced by lime, ash, or cement floors. The cob builders of past generations apparently made no use of the square, plumb-line, or level. No laths were used for the walls, which were plastered within; outside, rough-cast or "slap-dash" was laid on.

[Headnote: Mr. Baring-Gould]

_Mr. Baring-Gould's Testimony._--Mr. S. Baring-Gould, in his _Book of the West_, writing on the subject says: "No house can be considered more warm and cosy than that built of cob, especially when thatched. It is warm in winter and cool in summer, and I have known labourers bitterly bewail their fate in being transferred from an old fifteenth or sixteenth century cob cottage into a newly-built stone edifice of the most approved style, as they said it was like going out of warm life into a cold grave."

DEVON COB

The following paragraph, taken from C. B. Allen's _Cottage-Building_, is of interest:

"The cob walls of Devonshire have been known to last above a century without requiring the slightest repair, and the Rev. W. Elicombe, who has himself built several houses of two stories with cob walls, says that he was born in a cob-wall parsonage built in the reign of Elizabeth, or somewhat earlier, and that it had to be taken down to be rebuilt only in the year 1831."

_Fruit Walls._--Again quoting Mr. Baring-Gould: "Cob walls for garden fruit are incomparable. They retain the warmth of the sun and give it out through the night, and when protected on top by slates, tiles, or thatch, will last for centuries." It will be seen that the disadvantages of cob buildings are solely due to faults of construction, and not to any inherent defect in properly made cob as a material, and that the construction of cottages, farm buildings, and garden walls is well within the compass of an averagely intelligent workman.

It is not intended to argue that the cob cottage could be advantageously built in every county, but only that where it has been used and liked for centuries, a wise building policy would encourage its continuance. The materials are at hand, and the population ready to welcome this form of dwelling-place.

[Headnote: Old Cob Lore]

_An Old Authority._--An old writer treating of cottage-building thus delivers himself:

* * *

"A Bill for inclosing the waste lands of the kingdom having been introduced into the House of Commons, under the auspices of the Board of Agriculture, and as so beneficial a Bill cannot fail, sooner or later, to pass into a law, and as in consequence thereof, many small houses must necessarily be built, suited to small estates issuing out of allotments of such wastes, we have been induced to submit to the consideration of the Board three plans of such small houses to be built of different species of materials.

"The first is with mud walls, composed of soft mire and straw, well trodden together, and which, by degrees, is laid on, stratum-super-stratum, to the height required; a species of building not uncommon for cottages, and even for better houses, barns, etc., in the western and some other parts of the kingdom. It is the cheapest habitation that we can construct and is also very dry and comfortable."

* * *

And again:

* * *

"Walls of mud, or of compressed earth, are still more economical than those of timber, and if they were raised on brick or stone foundations, the height of a foot or 18 in. above the ground, or above the highest point at which dung or moist straw was ever likely to be placed against them, their durability would be equal to that of marble, if properly constructed and kept perfectly dry. The cob walls of Devonshire, which are formed of clay and straw trodden together by oxen, have been known to last above a century without requiring the slightest repair; and we think that there are many farmers, especially in America and Australia, who if they knew how easily walls of this description could be built, would often avail themselves of them for various agricultural purposes.

"The solidity of cob walls depends much upon their not being hurried in the process of making them, for if hurried, the walls will surely be crippled, that is, they will swag or swerve from the perpendicular. It is usual to pare down the sides of each successive rise before another is added to it. The instrument used for this purpose is like a baker's peel (a kind of wooden shovel for taking the bread out of the oven), but the cob-parer is made of iron. The lintels of the doors and windows and of the cupboards and other recesses are put in as the work advances (allowance being made for their settling), bedding them on cross pieces, and the walls being carried up solid. The respective openings are cut out after the work is well settled. In Devonshire the builders of cob-wall houses like to begin their work when the birds begin to build their nests, in order that there may be time to cover in the shell of the building before winter. The outer walls are plastered the following spring. Should the work be overtaken by winter before the roof is on, it is usual to put a temporary covering of thatch upon the walls, to protect them from the frost."

* * *

[Headnote: Mr. Fulford's Evidence]

_Mr. Fulford's Evidence._--Mr. Fulford, of Great Fulford, near Exeter, whose own village and estate can show as many good examples of old cob work as any place in Devon, writes as follows:

* * *

_Cost._--"It is not possible to give a close estimate of what would now be the comparative cost of a building in cob, stone, or brick, as this must depend upon the exact locality of the site. It may, however, be of assistance if I quote particulars of the relative cost of cob and stone building in Devon in the year 1808 when cob was in common use. The stonework referred to was rough rubble, and not with square or dressed blocks. It must be borne in mind that up to that date practically all material, stone, lime, etc., was carried on horses' backs. Wheeled carts which began to creep in about the beginning of 1800, were not in general use until twenty or thirty years later. As a boy I knew a farmer who remembered the first wheeled cart coming to Dunsford. In 1838 the Rector of Bridford (the 'Christowell' of Blackmore's novel) recorded the fact that in 1818 there was only one cart in the parish and it was scarcely used twice a year. In 1808 the price of building varied according to the district. In the northern part of the county the common price of stonework, including the value of three quarts of cider or beer daily, was from 22d. to 24d. the perch (16-1/2 ft.), 22 in. in width and 1 ft. in height. Including all expenses of quarrying and carriage of materials, stonework worked out at from 5s. to 6s. per perch running measure, and cob estimated in like manner at about 3s. 6d. Masons when not employed by the piece received 2s. per day, and allowance of beer or cider. In the Dunstone district (the clay shales from which make the best cob) masonwork was 18d. per rope of 20 ft. in length, 18 in. thick, and 1 ft. high, stone and all materials found and placed on the spot; cob work of the same measure was 14d. In the South Hams district masonwork cost 2s. 6d., and cob 2s. per perch of 18 ft. in length, 2 ft. thick, and 1 ft. high."

_Use of Shuttering._--"In those parts of the red land where Dunstone shillot or clay shale is not available, the red clay was mixed with small stones or gravel, and frequently the cob was laid and trodden down between side boards as used in building concrete walls. Three cartloads of clay built a perch and a half of wall 20 in. wide and 1 ft. deep. Eight bundles of barley straw, equal to one pack-horse load, were mixed and tempered with nine cartloads of clay."

_Roofing._--"Thatching in 1808 cost 8s. per square of 10 ft.; 100 sheaves of wheat-straw reed, weighing 25 lb. each, were sufficient for one square. Thatching, however, is not, as many suppose, indispensable as a roofing for cob buildings; slate found in many parts of Devon was frequently used, and of late years Welsh and Delabole slates, tiles, and unfortunately, from the picturesque point of view, corrugated iron, have to a large extent supplanted thatch."

_A Protective Wash._--"Vancouver, in his report on the Survey of Devon for the Board of Agriculture in 1808, gave the following recipe, which he described as a preserving and highly ornamental wash for rough-cast that was then getting into common use: 'Four parts of pounded lime, three of sand, two of pounded wood ashes, and one of scoria of iron, mixed well together and made sufficiently fluid to be applied with a brush. When dry it gives the appearance of new Portland stone, and affords an excellent protection against the penetrating force of the south-westerly storms."

_Rendering._--"For the rough-weather sides of cob buildings I have found cement and sand, finished with a rough surface, satisfactory, and far more durable than ordinary lime and gravel rough cast. For interior cob walls, laths are not necessary. The old plastering was frequently laid on too thick. Of late years I have used with excellent results granite silicon plaster for ceilings and walls. This requires no hair, and is easily applied."

_The Cob Tradition._--"Cob-making was, like many other local trades, carried on in some families from generation to generation and developed by them into an art, but apart from these specialists, practically every village mason and his labourers built as much with cob as they did with stone. There are men still left in various parts of the county who have made cob, and it would, in my opinion, be of advantage if demonstrations could be given by them to discharged sailors and soldiers who are anxious to take up work on the land."

_Training of ex-Soldiers._--"In cob-building, as in many other arts and crafts, a little showing is of far greater help to the novice than any amount of text-book instruction. The knowledge and experience that these men would gain from being shown, and better still, assisting an expert in making cob, would be of material advantage in the development of the county scheme promoted by the Central Land Association for the establishment of ex-Service men on the land. They could try their 'prentice hands on walls, tool-sheds, cart linhays, etc., for their own use, and some no doubt would develop into expert builders capable of constructing walls for dwelling-houses from approved plans."

_1819 Conditions Returned._--"The depletion of our home-grown timber supply and the prohibitive cost of practically all building material has in effect brought about the conditions that led our forefathers to utilise suitable material that lay nearest to hand, and unless some endeavour is made to follow their methods and profit by their example, it will be impossible to provide sufficient buildings for the necessary equipment of the allotments and small holdings, let alone housing accommodation for the workers on the land."

* * *

[Headnote: A Champion of Cob]

There is probably no one who knows more about cob than does Mr. Fulford--certainly no one who has done more to promote the revival of cob-building both by precept and example.

Cob is the traditional material of his native place, he has, as it were, been brought up on cob--he is familiar with both the ancient history and the modern practice of cob-building, and in short, he "knows."

When a revivalist has knowledge as well as enthusiasm, the grounds of his faith are usually worth serious attention.

II

_PISE DE TERRE_

Sec. I. GENERAL

_What it is._--"Pise de terre" is merely the French for rammed earth, and rammed earth is an exceedingly good material for the building of walls.

The odd thing is that its very obvious merits should have secured it such small attention.

It is no new-fangled war-time invention brought forth by our present necessity, but a very ancient system well proved by centuries of trial.

_History._--Pliny gives an excellent account of Pise-building in his _Natural History_, and Monsieur Gorffon, who published a treatise on this method of construction in 1772, states that it was first introduced into France by the Romans.

The following extracts from an old book based on a French original will serve well as an introduction to the study of Pise-building:

* * *

_Capabilities._--"An account of a method of building strong and durable houses, with no other materials than earth; which has been practised for ages in the province of Lyons, though little known in the rest of France, or in any other part of Europe. It appeared to be attended with so many advantages, that many gentlemen in this country who employ their leisure in the study of rural economy were induced to make a trial of its efficiency; and the result of their experiments has been of such a nature as to make them desire, by all possible means, to extend the knowledge and practice of so beneficial an art.

"The possibility of raising the walls of houses two or even three stories high, with earth only, which will sustain floors loaded with the heaviest weights, and of building the largest manufactories in this manner, may astonish every one who has not been an eye-witness of such things."

_Of Pise and its Origin._--"Pise is a very simple manual operation; it is merely by compressing earth in moulds or cases, that we may arrive at building houses of any size or height."

_Locale._--"This art, though at present confined to the single province of the Lyonese in France, was known and practised at a very early period of antiquity. The Abbe Rozier, in his _Journal de Physique_, says that he has discovered some traces of it (Pise) in Catalonia; so that Spain, like France, has a single province in which this ancient manner of building has been preserved. The art, however, well deserves to be introduced into more general use. The cheapness of the materials which it requires, and the great saving of time and labour which it admits of, must recommend it in all places and on all occasions, but the French author says that it will be found particularly useful in hilly countries, where carriage is difficult, and sometimes impracticable; and for farm buildings, which, as they must be made of considerable extent, are usually very expensive, without yielding any return."

[Headnote: Method of Building]

Sec. II. METHOD OF BUILDING

There is an exhaustive article on Pise in Vol. XXVII of _The Cyclopaedia or Universal Dictionary of Arts, Sciences, and Literature_, published in 1819. The writer, Abraham Rees, D.D., F.R.S., F.L.S., draws chiefly on French authorities and his directions are most detailed and precise.

_Definition._--He introduces his subject thus:

"Pise-building, in Rural Economy, the name of a method of building with loamy or other earthy matters, which has long been practised with great success, and in a very cheap manner, in some departments of France, and which is now had recourse to with similar advantage in some parts of this country. It has been described, delineated, and recommended by Mr. H. Holland in the first volume of _Communications to the Board of Agriculture_, and is to be managed somewhat in the manner directed below."

* * *

At great length and with immense detail, the plant, the preliminaries, and the process are each severally described.

The pith of the matter is sufficiently given by the following extracts:

_Shuttering._--"For the construction of the mould, take several planks, each 10 ft. long, of light wood, in order that the mould may be easy to handle; deal is the best as being least liable to warp. To prevent which the boards should be straight, sound, well seasoned, and with as few knots as possible. Let them be ploughed and tongued, and planed on both sides. Of these planks, fastened together with four strong ledges on each side, the mould must be made, 2 ft. 9 in. in height; and two handles should be fixed to each side.

"All the boards and ledges here mentioned must be, after they are planed, something more than 1 in. thick."

_Rammer._--"The instrument with which the earth is rammed into the mould is a tool of the greatest consequence, on which the firmness and durability, in short the perfection, of the work depends. It is called a pisoir, or rammer; and though it may appear very easy to make it, more difficulty will be found in the execution than is at first apprehended. A better idea of its construction may be formed by examining the Plate, in which it is delineated, than any words can convey. It should be made of hard wood, either ash, oak, beech, walnut, etc., or what is preferable, the roots of either of them."

_Method of Working._--"Pise contains all the best principles of masonry, together with some rules peculiar to itself, which are now to be explained.

"To begin with the foundation; this may be made of any kind of masonry that is durable, and should be raised to the height of 2 ft. above the ground; which is necessary to secure the walls from the moisture of the earth, and the splashing of the rain, which will drop from the eaves of the roof.[4] When these foundation walls are made level, and 18 in. thick, mark upon them the distance at which the joists are to be set, for receiving the moulds; those distances should be 3 ft. each from centre to centre. Each side of the mould being 10 ft. long, will divide into three lengths of 3 ft. each, and leave 6 in. at each end, which serve to lengthen the mould at the angles of the house and are useful for many other purposes. After having set the joists in their places, the masonry must be raised between them 6 in. higher, that is, to a level with the joists; there will, therefore, altogether be a base of 2-1/2 ft., which in most cases will be found more than sufficient to prevent the rain, frost, snow, or damp from injuring the walls. Raise the mould immediately on this new masonry, placing it over one of the angles of the wall.

[Footnote 4: The introduction of a damp-course and the provision
of gutters at the eaves greatly reduce the function of the
masonry base in modern work.]

[Headnote: The Ramming]

"A workman should be placed in each of the three divisions of the mould, the best workman being placed at the angle. He is to direct the work of the other two, and by occasionally applying a plumb-rule, to take care that the mould does not swerve from its upright position. The labourers who dig and prepare the earth must give it in small quantities to the workmen in the mould, who, after having spread it with their feet, begin to compress it with the rammer. They must only receive at a time so much as will cover the bottom of the mould to the thickness of 3 or 4 in. The first strokes of the rammer should be given close to the sides of the mould, but they must be afterwards applied to every other part of the surface; the men should then cross their strokes, so that the earth may be compressed in every direction. Those who stand next to one another in the mould should regulate their strokes so as to beat at the same time under the cord, because that part cannot be got at without difficulty, and must be struck obliquely; with this precaution, the whole will be equally compressed. The man at the angle of the wall should beat carefully against the head of the mould.

"Care must be taken that no fresh earth is received into the mould till the first layer is well beaten, which may be ascertained by striking it with a rammer; the stroke should leave hardly any print on the place. They must proceed in this manner to ram in layer after layer, till the whole mould is full. When this is done, the machine may be taken to pieces, and the earth which is contained will remain firm and upright, about 9 ft. in length and 2-1/2 ft. in height. The mould may then be replaced for another length, including 1 in. of that which has first been completed.

"The first course being thus completed, we proceed to the second; and here it must be observed that in each successive course we must proceed in a direction contrary to that of the preceding. It may easily be conceived, that with this precaution the joints of the several lengths will be inclined in opposite directions, which will contribute very much to the firmness of the work. There is no reason to fear overcharging the first course with the second, though but just laid; for three courses may be laid without danger in one day.

"This description of the first two courses is equally applicable to all the others, and will enable any person to build a house, with no other materials than earth, of whatever height and extent he pleases.

"With respect to the gables, they may be made without any difficulty, by merely making their inclination in the mould and working the earth accordingly."

Sec. III. THE THEORY AND SCIENCE OF PISE

_The Value of Ramming._--"Beating, or compression, is used in many different sorts of work; the ancients employed it in making their rough walls; the Italians employ it for the terraces which adorn their houses; the Moors for all their walls; the Spaniards, the French, and others for some of the floors of their apartments. The intent of the ancient architects, when they recommended the beating of cement and other compositions used in building, was to prevent them from shrinking and cracking; and it is employed for the same purpose in walls which are made of earth. The beater, by repeated strokes, forces out from the earth the superfluous water which is contained and closely unites all the particles together, by which means the natural attraction of these particles is made powerful to operate, as it is by other natural causes in the formation of stones. Hence arises the increasing strength and astonishing durability which houses of this kind are found to possess."

_An Experiment._--"Upon beating a small portion of earth, and weighing it immediately afterwards, it was found to weigh 39-1/2 lb. Fifteen days after, it had lost 4-1/4 lb. In the space of another fifteen days it lost but 1 lb.; and in fifteen days after that its weight diminished only 1/2 lb. In the space of about forty-five days the moisture was completely evaporated, and its weight was diminished about one-eighth; consequently only one-eighth of the whole mass was occupied by moisture, and this small proportion cannot at all affect the solidity and consistency of the earth so treated. This experiment is also sufficient to show the difference between this kind of building and that vulgar kind called in England 'mud-walling.'"

_Rate of Work._--"In one single day three courses of about 3 ft. each may be laid one over the other; so that a wall of earth of about 8 or 9 ft., or one story high, may be safely raised in one day. Experience has proved that as soon as the builders have raised their walls to a proper height for flooring, the heaviest beams and rafters may without danger be placed on the walls thus newly made; and that the thickest timber of a roof may be laid on the gables of pise the very instant they are completed."

[Headnote: Suitable Soils]

ON EARTH PROPER FOR BUILDING

_Suitable Soils._--"1st. All earths in general are fit for that use, when they have not the lightness of poor lands nor the stiffness of clay.

"2ndly. All earths fit for vegetation.

"3rdly. Brick-earths; but these, if they are used alone, are apt to crack, owing to the quantity of moisture which they contain. This, however, does not hinder persons who understand the business from using them to a good purpose.

"4thly. Strong earths, with a mixture of small gravel, which for that reason cannot serve for making either bricks, tiles, or pottery. These gravelly earths are very useful, and the best pise is made of them."

_Soil Tests._--"The following appearances indicate that the earth in which they are found is fit for building: when a pickaxe, spade, or plough brings up large lumps of earth at a time; when arable lands lies in clods or lumps; when field-mice have made themselves subterraneous passages in the earth; all these are favourable signs. When the roads of a village, having been worn away by the water continually running through them, are lower than the other lands, and the sides of those roads support themselves almost upright, it is a sure mark that pise may be executed in that village. One may also discover the fitness of the soil by trying to break with one's fingers the little clods of earth in the roads, and finding a difficulty in doing it; or by observing the ruts of the road, in which the cart-wheels make a sort of pise by their pressure; whenever there are deep ruts on a road, one may be sure of finding abundance of proper earth.

"Proper earth is found at the bottom of the slopes of low lands that are cultivated, because every year the rain brings down the fat or good earth. It is frequently found on the banks of the river, but above all, it is found at the foot of hills, and on all cultivated lands which have much slope. In digging trenches and cellars for building, it generally happens that what comes out of them is fit for the purpose."

ON THE MIXTURE OF EARTHS

_Soil Blending._--"As it may sometimes happen that earth of a proper quality is not to be found on the spot where it is intended to build, it becomes of importance to attend to the method of mixing earths; for though the earth which is near at hand may not of itself be proper, it is very probable that it may be rendered so by the mixture of a small quantity of another earth fetched from a distance. The principle on which a mixture must be made is very simple; strong earths must be tempered with light; those in which clay predominates, with others that are composed more of chalk and sand; and those of a rich, glutinous substance, with others of a poor and barren nature. The degree in which these qualities of the earths prevail must determine the proportions of the mixture; which it is impossible here to point out for every particular case, but which may be learnt by a little practice. Some easy methods will be described, by which any one may make a trial of the qualities of his earth.

"It will not be amiss to mix with the earth some small pebbles, gravel, rubbish of mortar, or in short any small mineral substances; but none of the animal or vegetable kind must be admitted.[5] Such hard substances bind the earth firmly between them, and being pressed and pressing in all directions, contribute very much to the solidity of the whole; so that well-worked earth, in which there is a mixture of gravel, becomes so hard at the end of two years that a chisel must be used to break it, as if it was freestone."

[Footnote 5: "The pise does not admit any vegetable or animal
substances. In mud walls they put straw, chopped hay, hair,
flocks, wool, etc., to make the mud adhere to the wood, or laths;
whereas the workmen who build in pise are careful to pick out the
least straw or the smallest bit of root which remains in the
earth: in short, the pise is a mineral substance imitating stone,
consequently anything that can slake or rot must be excluded."]

[Headnote: Experiments]

EXPERIMENTS TO ASCERTAIN THE QUALITIES OF ANY EARTH

_Trial by Experiment._--"Take a small wooden tub or pail, without a bottom, dig a hole in the ground of a court or garden, and at the bottom of that hole fix a piece of stone, flat and level; place your tub upon the stone, fill around it the earth that has been dug out to make the hole, and ram it well, that the tub may be enclosed, to prevent its bursting. Then ram into the tub the earth you mean to try; putting in, at each time, about the thickness of three or four fingers' breadths: when this is well rammed, add as much more, and ram it in the same manner, and so the third and fourth, etc., till the earth is raised above the brim. This superfluous earth must be scraped off extremely smooth, and rendered as even as the under-part will be, which lies on the stone. Loosen with a spade the earth around the tub, and you will then be able to take it out, and with it the compressed earth that it contains; then turn the tub upside down, and if it is wider at the top than at the bottom, as such vessels usually are, the pise will easily come out, but if it should happen to stick, let it dry in the air about twenty-four hours, and you will then find that the earth is loose enough to fall out of itself. You must be careful to cover this lump of pise with a little board; for though a shower of rain, falling in an oblique direction, will not injure it, yet it may be a little damaged if the rain falls perpendicularly, and especially if it remains upon it. Leave the lump exposed to the air, only covered with a board or flat stone, and if it continues without cracking or crumbling, and increases daily in density and compactness as its natural moisture decreases, you may be sure that the earth is fit for building. But you must remember that it is necessary that the earth employed should be taken from a little below the surface of the ground, in order that it may be neither too dry nor too wet; it must be observed also that if the earth is not well pressed around the outside of the tub before it is filled, though the hoops were of iron, they would burst, so great is the pressure of the beaten earth against the mould, of whatever size it may be."

_The Earth-ball Test--An Experiment which may be made at any time._--"Every person in walking on his ground may make little balls of earth and press them as tight as he can between his hands. If he brings them home and puts marks on them, he will by that means know the quality of every piece of land, and also be a judge of the mixture it will be necessary to make."

[Headnote: Preparation of the Earth]

ON THE PREPARATION OF THE EARTH FOR BUILDING

_Soil Preparation._--"All the operations of this art are very simple and easy; there is nothing to be done but to dig up the earth with a pickaxe, break the clods with a shovel, so as to divide it well, and then lay it in a heap, which is very necessary, because as the labourers throw it on that heap, the lumps of earth and large stones roll to the bottom, where another man may break them or draw them away with a rake. I must observe that there should be an interval of about an inch and a quarter between the teeth of the rake, that the stones and pebbles of the size of a walnut, or something more, may escape, and that it may draw off only the largest. If the earth that has been dug has not the proper quality, which is seldom the case, and it is necessary to fetch some better from a distance, then the mixture must be made in this manner: one man must throw one shovelful of the best sort, while the others throw five or six of the inferior sort on the heap, and so more or less according to the proportions which have been previously ascertained."

_Rain._--"No more earth should be prepared than the men can work in one day, or a little more, that they may not be in want; but if rain is expected, you must have at hand either planks, mats, or old cloths to lay over the heap of earth, so that the rain may not wet it; and then as soon as the rain is over, the men may resume their work, which, without this precaution, must be delayed; for it must be remembered that the earth cannot be used when it is either too dry or too wet, and therefore if the rain should wet it after it has been prepared, the men will be obliged to wait till it has recovered its proper consistency--a delay which would be equally disadvantageous to them and their employer. When the earth has been soaked by rain, instead of suffering compression, it becomes mud in the mould; even though it be but a little too moist, it cannot be worked; it swells under the blows of the rammer, and a stroke in one place makes it rise in another. When this is the case, it is better to stop the work, for the men find so much difficulty that it is not worth while to proceed. But there is not the same necessity of discontinuing the work when the earth is too dry, for it is easy to give it the necessary degree of moisture; in such a case it should be sprinkled with a watering-pot, and afterwards well mixed up together; it will then be fit for use."

_Organic Matter._--"It has already been observed that no vegetable substances should be left in the earth; therefore in digging, as well as in laying the earth in a heap, great care must be taken to pick out every bit of root, great and small, all sprigs and herbs, all bits of hay and straw, chips or shavings of woods, and in general everything that can rot or suffer a change in the earth."

ON THE BOND TIMBER TO BE USED IN BUILDINGS OF PISE

_Corners._--"To make good walls, it is not sufficient that the earth be well beaten, we must also learn to unite them well together. Here the binders cost very little; they consist only of thin pieces of wood, a few cramps and nails, and these are sufficient to give the greatest stability to buildings of pise."

Having gone on to explain that the angles of the building are formed by the successive courses alternately crossing one another on the corner like the alternating "long and short" quoins in a stone building, our authority proceeds to describe how rough boards are laid between the courses of pise so as to cross at the corner and so, entirely encased in tightly compressed earth, they form effective ties.

"This board must be rough, as the sawyers have left it, 5 or 6 ft. long, something less than 1 in. thick, and in breadth about 8, 9 or 10 in., so that there may remain on each side 4 or 5 in. of earth, if the wall is 18 in. thick; by this means the board will be entirely concealed in the body of the wall. When thus placed neither the air nor damp can reach it, and of course there is no danger of its rotting. This has been often proved by experience, as in taking down old houses of pise such boards have always been found perfectly sound, and many that had not even lost the colour of new wood. It is easy to conceive how much this board, from the pressure of the work raised above it, will help to bind together the two lengths of wall and to strengthen the angle."

_Bonders._--"It is useful (particularly when the earth is not of a very good quality) to put ends of planks into the pise after it has been rammed about half the height of the mould. These ends of planks should only be 10 or 11 in. long, to leave as before a few inches of earth on each side of the wall, if it is 18 in. thick; they should be laid crosswise (as the plank before mentioned is laid lengthwise) over the whole course, at the distance of about 2 ft. from one another, and will serve to equalise the pressure of the upper parts of the works on the lower course of the pise.

"The boards above mentioned need only be placed at the angles of the exterior wall, and in those parts where the courses of the partition walls join to those of the exterior wall, the same directions that have here been given for the second course must be observed at each succeeding course, up to the roof. By these means the reader will perceive that an innumerable quantity of holders or bondings will be formed, which sometimes draw to the right, sometimes to the left of the angles, and which powerfully unite the front walls with those of the partitions; the several parts deriving mutual support from one another, and the whole being rendered compact and solid."

[Headnote: The Strength of Pise]