(Note – SBH – Some of the sentence construction and grammar makes reading the following a little difficult at times but hopefully, it is understandable). 02/05/1849 – North British Agriculturist – Improvements suggested in brick making. (Mr Thomas Dean writes). You will oblige me by inserting in your valuable journal the following few remarks on…
1845 – John Young from Newton on Ayr, in collaboration with Robert Boyle produced a machine called the ‘Ayrshire Double Acting Patent Tile Machine’. This was adapted from an earlier machine patented by the Marquis of Tweeddale. The device was capable of producing 20,000 drain tiles per day. – Unknown source.
08/10/1845 – Dumfries and Galloway Standard – Highland and Agricultural Society show at Dumfries … Also exhibited was The Ayrshire Double Acting Tile Machine of very ingenious construction. It was exhibited in operation …
09/10/1845 – Perthshire Advertiser – Double acting tile machine – An important improvement in the manufacture of tiles has been affected by the patent machine above named, invented by Mr Young, engineer, Newton Ayr, and Mr Boyle, potter, Ayr; and is admitted, by competent judges, and, amongst the rest, very recently by Dr Sheirs, Professor of Agricultural Chemistry, Aberdeen, to the most perfect hitherto known. The machine does away with all the difficulties which have been found to attend pipe tile machines and Mr White’s invention. The tiles come from the Ayrshire Double Acting Machine without any curvature, and without any straining; and the cutting the tiles into equal length is admirably performed, without any cessation of the machinery, or any interruption whatever, as it is quite separate from, and acts independently of, the first moving power. It can make all sizes of tiles, from two inches to six inches in the bore, and can be changed from one kind to another in very short time with facility. With two men and five boys, properly qualified, 20,000 tiles can be produced in one day, which, at one foot long, would drain about ten acres of land at 20 feet apart.
11/10/1845 – Glasgow Citizen – Highland and Agricultural Society show at Dumfries – Amongst the implements and machinery which seemed to engage particular attention, we may particularise the following, which we range promiscuously:—Messrs. John Young A Robert Boyle’s (Ayr) double-acting patent tile machine, by which two men and four boys can produce 20,000 tiles, 40.000 soles in one day. All perfectly formed.
14/10/1845 – Fife Herald – Highland and Agricultural Society show at Dumfries – For approved patented articles not coming within the range of any of the foregoing articles – To Robert Boyle, Ayr for his patent tile machine, the medium gold medal or 5 sovereigns.
1853 – RHASS – On the properties of clay most suitable for making draining tiles and pipes by Mr Robert Boyle, tile manufacturer, Ayr.
[Premium—The Gold Medal.]
At the present time, when draining materials are of so much importance, and their application so essentially necessary as a preparatory step to all good farming, the manufacture of them should be gone about in a regular and systematic manner, which, when practised, its effects may produce a permanent character.
The selection and the preparation of clays for the manufacture of draining materials have hitherto been altogether overlooked, or spoken of so disparagingly by many, as to lead to the supposition that they are not of the slightest consequence. But unless the component parts of clays are thoroughly known, and the preparation it requires, before being made into a tile or pipe, be carefully attended to, the articles made from it will not withstand the induration necessary in the kiln, so as to insure their permanency. It cannot, therefore, be too much impressed upon the minds of those who are immediately concerned in this most important matter, that this preparatory step should never be neglected amidst the almost overwhelming mass of incongruities connected with the subsequent parts of the process. Thus premised, I will endeavour to point out in a plain and distinct manner what is requisite in the selection of a clay-ﬁeld, and the modes of preparation necessary to produce a useful and durable article from clay.
In the ﬁrst place, then. before the erection of tileworks, it is of the utmost importance that landowners should have their estates inspected by a competent judge, so that the best ﬁeld of clay may be selected as the site of the proposed manufactory. Much inconvenience, and sometimes great loss, have arisen from sites having been chosen hurriedly, and without duly ascertaining the quantity and quality of the raw clay.
I have known vast sums expended in the erection of tile establishments on the casual report of persons employed in the common operations of husbandry, who have concluded from the appearance of the soil, after being turned up, that abundance of the necessary material lay embedded below; whilst it ultimately turned out that the substratum, a few inches farther down, was entirely useless for the purpose. On the other hand, good ﬁelds of clay have been entirely overlooked from the appearance which the actual soil presented. I, therefore, repeat that an experienced individual should be employed to investigate thoroughly the whole extent of land intended to be occupied by the future operations.
It has been much practised, I understand, in many localities, when searching for clay, to use only the boring—rod, and to have the operation conducted by parties who have no practical knowledge of the business whatever; but this in no case should be resorted to, as the spiral motion given to the auger will to a certain extent so amalgamate the different strata which are pierced, that even an experienced eye cannot distinguish which clay is suitable, and which not. In all cases where such a narrow inspection is so essentially requisite, digging trenches with spades should be the only method resorted to. A staff of stout labourers, provided with spade and mattock, should accompany a person thoroughly versant with all the constituent parts of a good tile clay. Holes should be opened at regular intervals, and so wide at the top as to allow the men to go down with facility from 12 to 20 feet, by which the inspector thoroughly ascertains the quantity of available material, and tests the quality of every trench separately as they proceed downward.
When a good seam of clay is obtained in one part of a ﬁeld, operations must not be therefore suspended, and it taken for granted that the whole will be of the same character throughout, as I have sometimes seen one hole dug in a ﬁeld, and a good depth of excellent clay obtained, which did not extend to more than eighteen feet square, and beyond that space, the substratum was devoid of even the semblance of clay. I may mention a circumstance which I believe is not generally known by tilemakers, that all alluvial clays have been deposited into basin-shaped hollows, deep in their centre, and gradually becoming shallow to the extremities. I am at present working two ﬁelds of clay, which at the bottom of the basin is 20 feet deep, but which gradually become shallower as they extend outwards, to only a few inches of depth.
I am also working other fields of clay, where a great many trapdykes intervene, which are in general many feet broad at the bottom of the seam of clay, but gradually taper to a point as they approach the surface of the ground. I merely mention this, that those in pursuit of clay may not rest satisﬁed with a superﬁcial mode of exploring such a hidden treasure as clay, which, when brought to light, amply repays all the trouble bestowed on its search.
Strong, retentive clays, which are embedded not far below the surface, at the depth of, say, from three to six feet, are generally the best adapted for pipe and tile making, being soft and unctuous to the touch, readily absorbing and easily parting with moisture. A very ﬁne clay is sometimes found lying a good way below the surface, in horizontal strata, with alternate layers of ﬁne sand, so ﬁne indeed, that it has a muddy appearance. This clay is generally soft in its bed, and if immediately subjected to the inﬂuence of the pug-mill, will get softer as the process goes on; and if moulded in this state, will long retain the natural moisture, shrink very much in drying, and consequently make a very inferior article. But if this kind of clay be taken from the pit, where it naturally lay embedded and exposed for a length of time to the action of the air, ﬁssures will appear through it, and all the natural moisture escape from it; and although again saturated with water, it will not imbibe more than is necessary to bring it into a proper consistency; and when moulded into a tile or pipe, will shrink little in drying, and have great solidity after being burnt.
The best clays are those which are solid in their bed, which take a good deal of water to mollify them, have a tendency to stiffen in the preparation, and require no foreign ingredient to be incorporated with them. Tiles and pipes manufactured from this description of clay have great density, shrink little, and maintain their superiority throughout. Clays requiring any foreign ingredient can never be so intimately united with it as in the natural state; consequently, the article manufactured from them will not possess that durability so essentially requisite.
Good clays are found of all colours. The alluvial or carse clays are generally very free of stones, and they are frequently of a bluish tint, though sometimes rather weak in their nature. Clays of a higher formation are more or less interspersed with stones, are generally of a reddish-brown, but strong and durable. All clays to be manufactured into articles to withstand the action of the air should contain the oxide of iron, the ingredient which gives to clay a reddish colour when burnt, and the slight vitriﬁcation of which makes the material close in the texture, so that the manufactured article will not readily absorb moisture, and of course will retain its purity in all climates. Clays much devoid of the oxide of iron appear white after undergoing the process of burning, and are therefore only calculated to withstand an intense heat. These clays cannot be made fusible with any degree of heat that can be applied, consequently, articles made from them can only be made available for building the inside of air or blast furnaces; and bricks, tiles, or pipes, when manufactured from this description of clay, will not withstand the action of the air. By their porosity, they readily imbibe moisture, and expand With frost, and consequently crumble down to pieces.
When clay of a suitable quality is found on an estate, that can be made into tiles or pipes, its quantity should be carefully ascertained to warrant the proprietor in ﬁtting up the necessary erections for their manufacture. By making the following simple calculation, such a mistake will be easily avoided:— An acre of clay, at one foot deep, will make one million of common-sized draining tiles, three inches wide and twelve inches long; and taking the average distance at which drains are cut apart at twenty-four feet, there will be consumed 2281 tiles per Scotch acre, or 1815 per imperial acre; hence an acre of clay, one foot deep, will drain 438 Scotch acres, or 550 acres imperial. Thus we see that a ﬁeld of clay of considerable extent, and the quality good, is of great pecuniary value to a landowner.
Many estates throughout the kingdom are, however, destitute of such clays; and, in cases of this kind, tiles or pipes have either to be carted a considerable distance, or draining materials used not so well suited to the purpose.
In all districts where no ﬁne clays can be found, but where plenty of very coarse stony or sandy clay can be got, it should be narrowly examined, to ascertain whether the expense of removing the stones, etc., would be warranted in a pecuniary point of view. There can be no doubt that many clays may be made available for pipes and tiles that are considered wholly unﬁt for the purpose. But before entering upon the process, an estimate should be made whether the pipes can be produced economically in the circumstances.
A shortsighted landlord in Ayrshire, whose estate was much in want of draining, refusing to comply with the urgent requests of his steward to establish a tilework, gave, as the only reason for his refusal, that unsightly holes would be made in the ﬁeld out of which the clay would be taken; when the steward replied, that if tiles were made, and the whole estate drained thoroughly, in half a century the increased produce will have ﬁlled all the unsightly holes with gold. I am not sure that the steward’s opinion is so utopian as it appears at ﬁrst sight.
One thing essentially requisite in the selection Of a site for a tilework is to secure a proper level for carrying off the superabundant water, which, in low marshy situations, is so detrimental to clay being properly wrought. When it can be accomplished, a secure drain should be placed as near the bottom of the seam of clay as circumstances will allow, and so formed that the water may be retained or let off when necessary. Before commencing operations, the soil and all extraneous matter should be removed from the top of the clay, no organic matter being allowed to remain, or the tenacity of the clay will be lessened, and the articles produced from it will not emit that metallic sound which is the sure indication of an indestructible article.
The season most generally adopted for raising the clay is the winter months, when most other ﬁeld operations are suspended. Turning the clay repeatedly over in winter, and exposing it to frosts and thaws will be found very beneﬁcial.
Much has been said of late in regard to taking clay from its natural bed, and immediately subjecting it to the moulding process without any preparation. This theory has emanated from some recent inventors of tile and pipe machines and is recommended by them as an inducement to purchase their machines. To practical persons, however, this theory is known to be untenable. The most casual Observer has no doubt frequently perceived inequalities on the surface of draining-tiles, and at the same time observed that, when broken, such tiles are internally interspersed with seams of white matter. Both the unevenness and variation Of colour arise from the clay not having been incorporated before the moulding process took place.
Clay embedded in low marshy situations, more especially that found below moss, has when taken from its bed, such a ﬁne uniform plastic appearance, as to induce people of limited experience to conclude that it can be put into the pug—mill without any preparation, but nothing can be more erroneous than such a mode of procedure. It should be borne in mind that clays, as they lie embedded, are not uniform in their composition. Even the very ﬁnest of them have different portions of matter flowing irregularly through them and are more or less intersected with hard lumps, which, when acted upon separately, require different degrees of heat, so that if the clay be taken as it lies, and immediately subjected to a uniform temperature in the burning process, the result will be that the manufactured article will be shrivelled and uneven. But if the different ingredients of which clays are composed are intimately and minutely mixed before being subjected to the moulding process, we may conﬁdently expect to have a superior article, regular in all its parts, and of equal consistency. Hence the necessity of paying the utmost attention to the proper incorporation of all the component parts of raw clay.
To accomplish this desirable object, it has generally been the custom with tile manufacturers to raise, during the winter months, the clay intended to be made into tiles the following summer; and the operation is as follows:— A space is marked off, and all the soil and subsoil cleared away from the top of the clay. A cut of the clay (say about a yard in breadth, and the length of the space cleared) is ﬁrst thrown off, descending to the bottom of the seam, if not deeper than from six to nine feet, and this is left as an empty space for the next trench to be thrown upon, and so on to the end of the space marked off. This part of the process should be done carefully and systematically, as many of the errors committed may be traced to the slovenly manner in which this has been performed.
The clay should be cut with the spade into very thin slices, so as to expose the largest surface to air and frost. After lying some time as thrown off, the mass should be turned repeatedly from top to bottom, mixing the whole as intimately as possible.
During this operation, as much water should be given as the workmen think it will require to bring it to a proper consistency. The heap should then be levelled and smoothed on the top and covered over with turf or straw to preserve it from rain and drought. Still, with all this precaution on the part of the manufacturer, small lumps will be found through the clay, which no saturation in water, however, prolonged will dissolve and these lumps left undissolved, form one of the many inconveniences which beset the tilemaker.
There are two or three ways in which this difﬁculty may be obviated. The ﬁrst, and certainly the most complete plan, is the method I have practised these many years at one of my potteries, in preparing the clay for making articles of domestic use, spigot and faucet water-pipes, etc. The clay, after being taken from the pit, is thoroughly dried, then dissolved in water, and stirred up till it is brought to about the thickness of rich cream, after which it is strained through a ﬁne brass sieve, of from ﬁfty to seventy wires in the inch, thus getting quit of all extraneous matter. The water is then evaporated either by exposure or artiﬁcial means, till a regular consistency is obtained for working the clay, which is then close in the texture, smooth on the surface, and after being burnt will ring like bell-metal. This process involves a considerable expense and is considered by many too expensive to be adopted in the manufacturing of tiles or pipes for common furrow-drainage.
Another and effectual method can be more easily practised in a common tile establishment, which is, instead of raising the clay in the winter months and immersing it immediately amongst water, it should be dug in the course of the summer and put up in thin layers in an exposed and airy situation, the spadefuls being laid up so as to have a free circulation of air amongst them. In this way all the natural moisture escapes, ﬁssures made, and the whole becomes quite dry. Then, when the rainy season approaches, the mass expands, eﬁervesces, and crumbles to pieces; and the lumps, which no saturation in water, however, prolonged, can dissolve, become, between the alternations of drought and wet, transformed into minute particles. Then, by turning the whole mass over repeatedly prior to using it, it will be thoroughly incorporated, and secure the durability and good appearance of the article produced.
When the clay is subjected to this process, comparatively little loss in the drying or burning is incurred, the tiles being produced without shrivelling or twisting. The superior efﬁciency of this method of preparing the clay to that commonly adopted by the tile-manufacturer cannot be disputed and it is rather remarkable that nowhere in the course of my peregrinations have I seen it systematically adopted. The principal recommendation of the usual method is, that it employs the men at a season of the year when other operations of a tilework cannot be carried on. The superior advantages of this improved method, it is hoped, will induce our Spirited manufacturers to adopt it. By raising the clay in summer, and subjecting it to the process I have described, besides being the most effectual for dissolving the lumps which are naturally interspersed through the seam, it secures another great advantage to the manufacture of small pipe-tiles, by separating the stones and other extraneous matter from the clay, previous to its being pressed through the dies of a tile machine. In England, where the small thin tube of one-inch bore was ﬁrst introduced for draining purposes, it was found expedient that their manufacture should be conducted in such a manner as to insure a proper channel for the water to ﬂow in an even unbroken current; and an article that is necessarily so small as a tube for common drainage purposes should have a smooth uniform conduit, so that nothing may retard the run, or serve as a lodgment for any sediment that may ﬁnd its way into the tube.
In the making of pipe-tiles with machinery, as in every other new invention, many difﬁculties had to be encountered in the manufacture. Early attention was necessarily directed to cleanse the clay from all impurities, especially in those localities where clay naturally ﬁne could not be had but nothing effectual, and at the same time economical, was for many years adopted. In Norfolk, Suffolk, Kent, and Essex, an attempt was made to wash the clay from all impurities, a process somewhat similar to what I have mentioned as being used about potteries but at that time the expense seemed so formidable that it never came to be generally adopted.
About small establishments, the apparatus for effectually washing the clay, and the necessary labour attending it erected a complete barrier against its adoption. As every attempt to obviate the pressing evil should be made public, I will, in a plain manner, endeavour to describe the most economical method of washing clay, and of bringing it into the ﬁttest state for the manufacture of small tubes.
Before commencing to wash the clay, a suitable spot must be selected upon which to erect the necessary apparatus. A small piece of table-land, with the ground, gradually rising behind and sloping downwards in front, if such can be found, will be the most eligible. A circle of about 9 feet in diameter is ﬁrst marked off, and bedded with hard-ﬁred bricks laid on edge; a wall is then raised around the circle to the height of 3 or 4 feet, and a second one is also raised the same height, 4 feet within the outer one. The spaces between the walls forming the vessel in which the clay is put to undergo the process of washing. An upright spindle is then ﬁxed in the centre of the circle, from which three strong arms are extended to the length of the outer wall. To one of these arms is attached an iron roller, which moves between the walls, and to the other two arms are attached implements of iron similar to a harrow. A horizontal pole is then attached to the extreme point of the upright spindle, and extending a good way beyond the outer wall, and by which, a horse moves the harrows and the roller around the circle. A stream of water must, if possible, be conducted by a pipe into where the washing is performed, which can be let off or on as required. The clay, which of course must have been previously turned over and properly molliﬁed, is then wheeled by the workmen into the washing-circle, and a sufﬁcient quantity of water let in upon it. The horse then moves round the rollers and harrows, the former pressing downwards, and crushing the lumps, the latter raising up and separating the mass and thus both act alternately till the whole contents assume a pulpy appearance. A close grating or sieve, one-foot square is ﬁxed at the one side of the washing-circle, and is protected by an iron sluice whilst the operation of washing is going on. When the washing is completed, the sluice is opened, and the water-holding the clay in solution runs through the sieve, whilst the stones and other extraneous ingredients are retained within the circle, which is then cleaned out by the workmen, and more clay put into it and the same operation is repeated, till a suﬂicient quantity of clay has been washed.
A space of ground contiguous to the washing-circle must be formed into a receptacle for the dissolved clay after it passes through the sieve, having an inclination of at least 4 feet below where the washing is performed. This piece of ground must be carefully hollowed out, and an embankment put around the sides of it to the height of 3 feet and around its bottom must be a close and efﬁcient drain, to draw off the superabundant moisture. The pulpy clay, when run into this receptacle, will very soon settle down towards the bottom, the water remaining at the top till evaporated, and the clay attain that consistency which is most suitable for pipe-tile making. To assist the evaporation, small ruts may be formed along the top of the mass to convey the moisture to one common point, where it may be run off to the lower extremity of the ﬁeld.
The most suitable season for conducting this washing is in the winter months; and when the spring approaches, the clay will have become so consolidated that pipe—tile making may be resumed at the usual period. To prevent the washed clay from getting hard and crusted on the top during the drying months of spring and summer, a layer of ﬁne sand should be spread over the top, which, if required, can be mixed amongst the clay when carried to the mill or, if found inexpedient to do so, it can easily be laid aside for further use.
When clay is subjected to this ordeal, its quality will be very materially enhanced, (apart altogether from the mere taking out of the stones, &c.,) as all the different ingredients of which clays are composed will be intimately and minutely mixed, so that no undue shrinkage nor shrivelling will be observable in the body of the manufactured article, consequently, the waste will be but triﬂing in comparison to what takes place With the usual routine of a tile-yard.
It has always been a subject of a general complaint by practical drainers, that small tubes are invariably twisted, and that consequently, much difﬁculty arises in securing a proper conduit with them at the bottom of the deep drains. This evil, however, would be greatly modiﬁed, if not altogether obviated, by the washing process. It is also of the utmost importance that the external and internal parts of a pipe-tile be made smooth and glossy, which will secure it from imbibing water and expanding by frost, and will serve also as a preventive from the inner surface of the tube accumulating any incrustation. Both desirable properties will be fully secured by properly washing and separating the extraneous matter from the raw clay.
Where brickmaking is carried on to a great extent, steam-power is sometimes applied to this washing process, by which a quantity of clay is made soluble, and passed through the sieve in one day, which is sufﬁcient to make 60,000 bricks. In pipe and tile establishments, therefore, where steam-power is used to drive the machinery in the tile making season, the same power might be made available in winter to drive the washing apparatus. Although the washing of clay has hitherto seemed a formidable operation, incurring a considerable outlay at ﬁrst, and much labour in the process, so much so, as might lead people to think it altogether unwarranted in a small tile-yard. I am perfectly convinced, that in a large establishment, where there is a demand for small tubes, the superiority of the article manufactured from washed clay, over that which is not washed, the small amount of breakage, and the additional price they obtain in the market, will about counterbalance the outlay incurred in the washing process. The method of cleansing the clay by washing as I have described is, undoubtedly, the most effectual, and when used for the manufacture of small pipes, will be found to possess many advantages which are not attainable by any other method. But where only a limited supply of these small pipes is required, it may not, in a pecuniary point of view, he thought advisable to adopt such an extensive process of the reﬁnement of the clay.
Having heard so much about washing clay, as practised by tilemakers south of the Tweed, and particularly by the brickmakers around London, I visited some of the brickyards near London and saw how the process was carried on there, which is performed on a similar principle to that which I have described. The washing, or rather the mixing the clay, is principally performed by the brickmakers of London, by having certain ingredients mixed in the mass, principally chalk, so as to give the bricks as near the colour of stone as possible for particular buildings; but when the clay is mixed with chalk or lime, great care must be taken in the burning process. I may remark here, in passing, that there is a process going on and ingredients used in some of the London brickyards, which serve two purposes, and which cannot be surpassed in an economical point of view. Coal-ashes, or, as they are termed, breeze, are collected and submitted to the action of bruising rollers, for pulverisation. They are then mixed amongst the brick clay to the extent, perhaps, of 10 tons to 300 cubic yards of clay. The bricks, when thoroughly dry, are put into clamps, built 33 rows in height. There is no fuel put between the rows of brick, except with the 3 bottom rows, as there is as much of the breeze interspersed amongst the bricks as to burn them thoroughly. After the clamp is set ﬁre to, it will take one month before a regular heat come to the top. The bricks at both ends are then taken down, the external air forcing the ﬁre inwards till the ﬁre meet in the middle of the clamp, and all are thoroughly burned but this is a digression from the subject in hand.
In some of the early introduced pipe-tile machines, such as the Benenden machine, Clayton’s, etc, a grating was inserted into the cylinder immediately above the chamber, through which the clay is expressed, to separate the stones from the clay. But with clay of the consistency necessary for the manufacture of pipe-tiles, there is no machine driven by hand which can effectually be wrought so as to separate the stones from the clay, and at the same time press it regularly through the dies. At the Highland and Agricultural Society’s show last held at Edinburgh, Clayton’s pipe-tile machine was exhibited, by which both the cleansing of the clay and the moulding of the pipes were attempted simultaneously by manual labour, but the double operation was performed with too much evident exhaustion of the men.
The gratings for cleansing the clay are generally made with longitudinal bars of iron, of the same distance asunder as the thickness of the dies of the machine but this arrangement has not the desired effect, as every long thin piece of stone will ﬁnd easy egress through the longitudinal grating. When thin slaty stones occur in the clay in the chamber, they almost invariably present themselves to the dies in such a position as to interrupt the uniform progress of the clay outwards. Instead of the grates having longitudinal bars, a cast-iron plate, perforated with round holes of a somewhat less diameter than the thickness of the dies of the machine, should be introduced, and which will intercept any stone in the clay.
Great, however, as the beneﬁt undoubtedly is, in having round perforated holes in the screen-plate, an inconvenience arises from the power required to force the clay through them, which will far
exceed that required with the longitudinal bars, thus rendering the double operation of screening and moulding not easily attainable by manual labour. With the greater number of the recently
invented pipe-tile machines, the process of cleansing the clay has to be performed by itself, and which nearly takes the same amount of labour as that required for moulding the pipes, thus adding a considerable cost on every thousand produced.
A great improvement in the screening process has of late been effected by Mr George West, Riccarton, Linlithgow, by a simple apparatus to act in combination with the pug-mill, by which the
double process of milling and screening is performed w1th great precision, and at a reduced expenditure. On the top of the pug-mill, and ﬁxed on its spindle, is a large spur-wheel. Adjacent to the mill is a horizontal box, which at its farther extremity has two receptacles for receiving the clay previous to its being screened. A plate of iron, perforated with holes, is ﬁxed in each receptacle, through which the clay is expressed by pistons acting alternately. The pistons are attached to a strong horizontal shaft, with a considerable length of crank, the whole being set in motion by a wheel acting in unison with the formerly mentioned spur-wheel. The perforated plates used in the screening process are raised up and let down by the action of a screw when found necessary to be relieved from the stones and lumps which accumulate behind, and which are pushed out by the reciprocal movement of the two pistons. The plates being again let down, the screening is resumed without any delay taking place. The whole machinery of the pug-mill and the screening apparatus are wrought with ease by one horse and can be erected for £21.
Taking the operation of screening by itself, it can be performed by two stout lads, the one putting in the clay and the other carrying it away, and who are able to cleanse a sufﬁcient quantity to make 10,000 pipe-tiles per day. An objection might be raised against the screening apparatus acting in conjunction with the pug-mill, in as much as the milling and screening together will exceed the power of one horse. This no doubt would be the case, provided the pug-mill was made with the usual number of arms and knives required in one of a common tile establishment, but so large a mill is unnecessary when the screening apparatus is attached to it. The pressing of clay through small perforated round holes, besides removing the stones, reduces the large lumps which may be intermixed, bringing them to a more uniform consistency than can be attained by the internal machinery of a pug-mill. In an establishment where from 20,000 to 30,000 tiles are required to be made weekly, at small steam-power will be found considerably cheaper to drive the pug-mill than horse-power, and it does its work more effectually—and nothing is easier than to adapt steam power to the pug-mill and rollers.
Tubular tiles for drainage purposes, having undergone severe scrutiny, are now considered the most efﬁcient and economical material by many of our leading agriculturists. It follows, as a natural consequence, that the manufacture of these small tubes must be conducted in such a manner, and the clay so prepared, as to form an entire and smooth conduit at the bottom of a drain, so as to secure the conﬁdence of the practical drainer. The generality of clays found in Scotland are very unsuitable for the manufacture of small tubes when taken from their natural bed hence the necessity of adopting some method of ameliorating them and excluding extraneous matter from them. The old method of preparing the clay is in many instances still adhered to in common tile establishments, when endeavouring to make small tubes but it is very inadequate for the purpose and the article produced must be very inferior. An entirely improved and systematic arrangement must be adopted through the whole process of the manufacture, or we may rest assured that no tiles will emanate from it possessing a permanently useful character.
In the common method of preparing clay, if any lumps should remain undissolved, or if small pieces of limestone are in the clay, bruising rollers will be found very advantageous, to be used previous to the clay being put into the pug-mill. The action of the rollers will crush these ingredients into such minute particles, and the mill so diffuses them through the clay, that no bad effect will be observable in the manufactured article. But if nodules of limestone be allowed to remain whole amongst the clay and be made up into the tiles or pipes, and although not observable when
newly burned, they will, whenever damp comes into contact with them, expand, and cause the tile to crumble to pieces.
The rollers I use are 18 inches long and 12 inches in diameter and are placed in a cast-iron frame, with a box on the top, into which the workmen put the clay which the rollers catch as they revolve. An endless web is immediately placed below the rollers, which the clay drops upon, and is conveyed by the web and emptied into the pug-mill. The construction of a pug-mill is so generally known that a minute detail is unnecessary. I may only mention, that when steam-power is used instead of horse, a larger number of knives and arms can be introduced into the mill and a greater pressure applied, thereby bringing the clay to a more uniform consistency, and producing a greater quantity in a given space of time.
When the engine has plenty of power, the pug-mill may be put down in a horizontal position, which will be found a convenient one for having the bruising rollers placed immediately above it, so that the clay may drop from the rollers of its own gravity. Where bruising rollers are not used, a horizontal position is considered by many as convenient for the purpose of emptying the clay from the barrows at once into the mill, thereby saving the labour of one person but this is questionable economy. I am of the opinion that no clay should be emptied loosely in large masses into the mill, but should be introduced into it in single spadefuls, thereby securing an equal distribution in the mill and a regular pressure upon it downwards.
It is a common practice in many tileworks to take the clay from its natural bed, and immediately tumble it into the mill, when many parts of the mass must be hard and lumpy, the workmen thinking to mollify it by throwing water upon it whilst in the mill, which only increases the evil greatly, as the wetted clay either slips through without being properly acted upon by the knives, or the wetted sides of the cylinder cease to resist the pressure from the arms and knives, in consequence of which the entire mass of the clay revolves around with the spindle, the machinery thus ceasing to make a proper amalgamation of the clay, which issues from the mill in a loose and unincorporated state.
If the clay were wheeled in and beaten up in a batch around the mill, some time previous to its being used, its quality would be materially improved, as the dry parts will have absorbed moisture
from the wet ones, causing a uniform moisture through the heap and if the pugged clay were beaten up into a mass for a considerable period before being used, its composition would become more
Something similar to the above method in kind, if not in degree, is found indispensably necessary in porcelain manufactures. The longer the ingredients from which the ﬁne porcelain is manufactured remain in contact before being used, the sounder and better is the article produced.
The Chinese, who were long famed for the manufacture of ﬁne porcelain, seemed to be fully aware of the great beneﬁts resulting from having the united ingredients piled up for a long period
before being used, sometimes extending to nearly half a century. Many potters in China, knowing well that they could not leave anything more valuable to their descendants, have bequeathed them as much of the prepared material as would serve an ordinary lifetime.
There is a particular kind of clay, of which I have had a good deal of experience, that requires a different mode of preparation to those clays more generally in use. This clay, in appearance, is
similar to the shales of the coal formation, but is strongly impregnated with the oxide of iron, and is generally found in deep strata. It is hard and brittle, and seemingly devoid of the unctuosity possessed by other clays. It lies pretty solid in the bed, requiring the use of the pickaxe. When newly dug, it rises in lumps, and will not dissolve readily by the action of the atmosphere, or of water. When dissolved, however, (which is most readily accomplished by artiﬁcial means,) and properly mixed with the soft unctuous clay generally found above it, a very desirable article is produced from it.
On the extensive estates of the Earl of Derby, Knowlesly, near Liverpool, there is a very large ﬁeld of this kind of clay, upon which, under my direction, an extensive tile establishment was erected some time ago. The tiles which I manufactured from it were excellent in quality and very durable. As it may be of use to those proprietors who may have clay of the same kind, I will describe the method which I adopted for preparing it previous to its undergoing the moulding process. The soft clay is taken off the top and wheeled aside. The hard, lumpy, brittle kind, is then raised and put through two pairs of powerful bruising rollers. These rollers are set in a cast-iron frame, one pair being placed immediately above the other, that the clay may drop from the upper ones into those below of its own gravity. The upper pair of rollers are placed considerably wider than the lower, that they may the more readily receive the larger lumps. The lower ones are placed so as they can be regulated according to the ﬁneness of the clay wanted. These rollers may be either set in motion by steam or horsepower. When by steam, which is the most effectual method, a lying shaft is connected with the engine to drive the rollers, which are placed adjacent to the clay-pit. The clay passes through the rollers very quickly and is then wheeled out and mixed properly with part or whole of the soft top clay.
This process is performed in the winter season and when the tilemaking season approaches, the prepared mass is subjected to the action of another pair of rollers, which empty themselves into the pug-mill by an endless web. This grinding and mixing, no doubt creates a great deal of extra trouble and adds considerably to the expense of manufacturing the tiles, but, when conducted in a proper manner, this clay makes a very durable article.
There are many places where clay of the above description has been overlooked, and hitherto considered impracticable for the manufacture of draining materials. In localities where no other kind of clay exists, and softer materials are at a great distance, the above plan may be adopted with considerable advantage by the proprietor. On one of the Marquis of Bute’s estates in Ayrshire, there is a very large ﬁeld of clay of this kind, although not so strongly impregnated with the oxide of iron and on it erections were put up and the manufacture of tiles, by the usual process, attempted. The
result, however, as might be imagined, was a complete failure and the work abandoned. As no other ﬁeld of clay could be found in that locality, and as the estate was much in want of draining, the failure was a source of deep regret to the late noble Marquis. In the emergency, I was applied to and suggested and put in practice the above plan, which has been in operation for some time and if carried on skillfully and systematically, a large supply of excellent draining materials might be the consequence.
The large bank of clay on the road from Newcastle to the Staffordshire potteries, out of which the well-known blue-coloured water-pipes, bricks, and draining-tiles are manufactured, is similar
in appearance, to that, I have been describing. The Staffordshire clay is taken from a bank considerably beyond one hundred feet in depth, and it undergoes the operation of grinding between
rollers previous to its being manufactured.
On the Liverpool and Birmingham Railway, the traveller cannot fail to be much struck with the beautiful and enduring appearance of the bricks used in the construction of the different bridges near Whitmore Station, which are all manufactured from the above kind of clay. An estate of large size, having no tile establishment, and having the draining materials carted from a distance, incurs a considerable yearly expenditure. It is, however, reasoned by many proprietors, that as the tenants cart all the materials, the expense does not fall upon themselves and hence they do not exert themselves to make that material available, which perhaps lies embedded below the surface of their estates, and which, by a judicious arrangement, might no doubt afford mutual beneﬁt to landlord and tenant.
It is of paramount importance at the present time when everything connected with draining is invested with peculiar interest, that correct views should be disseminated regarding the nature of clays, and any artiﬁcial process which may be recommended for their improvement; and, as regards the latter, nothing should be attempted to give certain qualities to clay which it does not naturally possess unless it can be simply and economically done. I am tempted to make this remark in order to counteract certain theoretical notions which have lately appeared regarding mixing clays with foreign ingredients, or mixing two clayﬁeld, which, taken by themselves, are unﬁt for tile or pipe making, when it is recommended to extract the good clay from each and make a medium one between them. However plausible this theory may seem to the uninitiated, it can never be carried into practice to the extent, they would have us to believe. 0n the qualities of play, too, there has been much theory and little practice and the instruction given on them in the classroom has been conﬁned there, instead of being carried out in the tileyard.
In making small tubes, artiﬁcial means must be resorted to with the generality of clays found in Scotland, so as they may pass through the d1es of a pipe machine in a satisfactory manner. A great majority of the clays of England are much ﬁner than the Scotch clays and free of any gritty substance that retards their progress through the dies of a pipe-tile machine; hence many English pipe-tile machines are unavailable when put in use on the north of the Tweed.
Many of the English clays, being very unctuous, take on a very ﬁne skin in passing through the dies, and hence their small tubular pipes have a very beautiful appearance, compared with those from the Scotch manufactories. The round, plump appearance of the English pipe—tiles is much admired, and exhibited in this country as a pattern of excellence but it invariably happens that they are very small in the calibre. Where pipe-tiles are made, means must be used to preserve their round, plump appearance, after they emerge from the dies, other than merely placing them upon a plain board for upon such a surface their tubular shape will not be retained.
Clay, that it may progress freely through dies, and retain its adhesive quality must be brought to a certain consistency but such a state of the clay prevents the pipe-tiles from sustaining their own weight, when placed on the shelves of a drying-shed, where they collapse and crack at the point where the weight more immediately presses upon them. In placing any truly cylindrical article upon a plain surface, not more than one-twentieth part of its circumference rests upon it, which is a very small proportion to bear the whole weight, consequently plastic material must collapse with Such a superincumbent pressure. To remedy this inconvenience, a method is adopted, which in most cases proves effectual, but which of course adds to the cost of manufacturing the pipe-tiles. When they have been some time upon the drying shelves and their drying forwarded to a degree which will not affect the adhesion of the different particles of which clays are composed and are able to sustain their own weight, they are taken from the drying shelves singly and placed on a table, and a roller inserted within them. The roller is made to revolve backwards and forwards several times by the motion of a boys hands till the pipe-tile resumes the tubular form, when it is replaced upon the drying shelf, to prepare for removal to the kiln. In the rolling process, great care is requisite to take the pipe tiles at the proper time, and to employ a skilful operator, or the evil will be increased instead of being removed.
I have recently adopted a simple method, which I have every reason to believe will go far to supersede the rolling process, and lessen the cost of making, which I will now describe in such a manner as will enable anyone to understand the principle upon which it is based. In making pipes, say of two inches in diameter, oblong pieces of wood are taken, two inches on the square and of such a length as thoroughly to cross the drying shelves. These pieces of wood are sawn asunder diagonally and both halves are placed parallel to each other upon the shelves loosely, to form a seat for the new formed pipe-tiles, which there retain their pristine shape. These angular-shaped pieces of wood also prevent the pipe-tiles warping or twisting on the drying shelves, which all clays are liable to, however ﬁne, when propelled through the dies of a pipe-tile machine, and thereafter placed on a plane surface. Collars for draining-tubes, which were for a time used extensively in England, and in some places of Scotland, are now considered by many so expensive, and so clumsy and ineffective, that they are fast falling into disrepute. The cylindrical pipe is alone used in many places, but when small in the tube it makes a defective drain.
To obviate the evils attending drainage with small tubes, a species of bell-shaped pipe-tile has been recently introduced, in imitation of the small water-pipes, which used to be made on the potter’s wheel. The bellmouth is formed on these pipe-tiles in a very simple and expeditious manner, as follows:- The round horse that is used for lifting the pipe-tiles from the machine is formed with a gentle swell towards the end which is next to the boy’s hand. The boy, after inserting it into the pipe-tile as far as it will easily go, lifts and turns the pipe-tile up till it assumes a perpendicular position, when he strikes the end of the horse gently upon the table, which brings the one end of the pipe-tile a little way over the swelled part of the horse, and forms it into a sort of bellmouth, which, when burned, becomes a ﬁt receptacle for the smaller end of another pipe-tile to occupy; so that when laid down in a drain, such pipe-tiles sustain one another, and no derangement can take place.
To make good pipe-tiles with a bellmouth, the clay must be well made, otherwise, the strain upon the end of the pipe-tile, in covering the swollen end of the horse, must of necessity cause the
clay, however well-prepared, partially to separate and if it is ill-prepared, rents will be the consequence, and the pipe-tile rendered unﬁt for use. Caution must also be used in placing these bellmouth pipe-tiles in the kiln, as the swelled portion is apt to get damaged in the burning. Hence bell-mouthed pipes, being joined by weakening an important part, are not what a drainer should
Before concluding, I may be permitted to make a few remarks on the clay most suitable for making spigot and faucet water- pipes 0n the deposits found in drains, on flowerpots, &c., which, although not strictly relevant to the subject under consideration, may be interesting.
In the bill passed regulating the sanitary condition of towns, a clause empowers commissioners to construct proper drains, in order to remove nuisances from houses, from which a question will naturally arise, how such drains are to be constructed, and what is the best kind of material to be used in the formation of the conduit.
Freestone has hitherto been much used for common sewers, and even for ordinary drains, the idea being that that material possesses both indestructibility and efﬁciency beyond every other.
Nothing, however, can be more fallacious than such an opinion. Every drain should be so constructed as to take instantaneously and thoroughly away every refuse from human habitations. The
general form of these stone drains, however, are very inadequate for this purpose, they forming a continuation of cesspools, well calculated for retaining ﬁlth and engendering malaria.
Circular brick drains have sometimes been resorted to but they also, form bad conduits where despatch is so essentially necessary since the friction inevitable in a drain formed of common bricks,
and the lodgment of ﬁlth occasioned by rugged edges and corners, form a long series of cesspools throughout the conduit.
Earthenware pipes, both for sanitary and domestic purposes, have hitherto been partially used, and, when made in a skilful manner, are found efﬁcient and economical. A few hints regarding
the proper material for their construction, its preparation, and their manufacture may be of use at the present time. In the ﬁrst place, then, clays impregnated with the oxide of iron will be found the best material, provided it is prepared in a proper manner. Let it be impressed, therefore, on the mind, that all clays to be manufactured into articles to withstand the action of the air, for undergoing a high hydraulic pressure, and remaining undeteriorated under every variation of climate should be plastic, tenacious, and strongly impregnated with the oxide of iron, an ingredient which gives a beautiful red tinge when burned, and when combined with the alumina and silica of the clay, will, by its necessary induration in the kiln, undergo a vitriﬁcation sufﬁcient to make the article as close in the texture as marble, and which will not absorb water. This clay being very adhesive, and rendered compact by the process of sifting and boiling, which I have described, makes it unquestionably the most efﬁcient material for spigot and faucet water-pipes, intended either for sanitary or domestic purposes.
Whilst, however, this kind of clay can be made so eﬁiment by the process described, it is totally unﬁt for the purpose when used in its natural state, and all water-pipes made from it in that state
should be rejected. An attempt has recently been made at different places to produce water-pipes from the common drain-tile clay, taken rough and raw from its natural bed. The very slight preparation it receives by the action of a common pug-mill, the barbarous method adopted in forming the pipe, bending the clay around a circular piece of wood, and clumsily joining its edges by simply pressing them together by the hand, (which joining is almost invariably perceptible after undergoing burning,) must render them very inferior. In addition to this, these water-pipes are burned in a common drain-tile kiln, some being hard ﬁred and some soft so, taking them as they are, it is difﬁcult to conceive how people are induced to use them as a permanent improvement.
Fire-clay pipes are sometimes used for conveying water, but, from the nature of the ingredients of which they are composed, great porosity and want of adhesion render them unﬁt to stand much pressure, or to resist the alternations of weather which occur in this variable climate. The porousness of the common furrow-draining pipe-tiles has often been lauded, especially in England, because a certain amount of drainage, it is said, is effected by the percolation of the water through the body of the tube. To burn a pipe-tile, however, as it should be, the more fusible parts of its composition will be acted upon by the heated air of the kiln, so as to close up the porosity, and make it ﬁrm in its texture; whereas a porous pipe-tile is one not brought to that pitch of heat in the kiln capable of vitrifying the more fusible parts, and hence parts of it will to a certain extent remain detached and be liable to separate altogether.
Therefore the absorbent or percolating qualities of pipe-tiles are a sure criterion that their permanency cannot be depended on. I have no doubt that the roots of plants or incrustations being
found in the interior of pipe-tiles may be ascribed either to the unsuitableness of the materials or to the materials being loosely put together and unskilfully manufactured. If the internal parts
of a pipe-tile be made smooth and glossy, it will secure it from imbibing water or expanding with frost, and be a preventive against any incrustation, or ingress to the roots of plants. I may, therefore, repeat, that tiles of all kinds can only be rendered durable by properly separating their material from all extraneous matter, and subjecting them to a high temperature in the kiln. As the obstruction of drains by the roots of plants, incrustation, etc has recently been brought prominently forward by some of our leading agriculturalists, I may be allowed to direct their attention brieﬂy to what I consider a convincing proof that the obstruction complained of may in a great measure be traced to the method by which drains are formed and the unsuitable materials placed 1n them, and to illustrate the subject more fully, I would, in the ﬁrst place, allude to the manufacture of ﬂowerpots, and show how they conduce either to the welfare or destruction of the plants placed in them. All who have had the experience of the ﬂower-garden must be aware that, to insure a regular and satisfactory development of plants in pots, they must have them made so as the ﬁbres of the most delicate plant may not recoil when coming into contact with their sides. It is not enough for the practical gardener that the pots be exquisitely formed and elaborately ornamented he must have them slightly tapered downward, ﬁnished with an egg-shaped bottom, and porous throughout.
The general mode of manufacturing ﬂowerpots is very ill-calculated to meet the views of the practical gardener. The clay does not receive a preparation calculated to produce a uniformity in all its ingredients but is placed unprepared into the hands of the thrower, who, in its manuduction, leaves ridges in the interior, which, in the unpotting of the plant, prove injurious to its tender roots. The greatest evil, however, in all ﬂower pots which are ﬁnished solely by the thrower, is the ﬁne skin produced by the friction of his hands, which compresses the plastic material to such a degree that the rind is rendered impervious to the air and water, especially when the pots undergo a high temperature in the kiln. Hence the impossibility of any plant growing luxuriantly in such an impenetrable encasement. To remedy this evil, I have of late used the turning-lathe in the manufacture of garden-pots. At potteries where the turning lathe is required to give the ﬁner kinds of Ware a nice appearance, (not attainable by the thrower,) an iron tool is used upon the pots in the green state, that is, between the wet and the dry state to pare away everything superﬂuous, which operation, while it lightens the articles, necessarily takes away the smoothness which the thrower had given to the outside by the action of his hands, leaving the body of the pot quite porous. This porosity serves as a series of receptacles from which the plant receives its proper nourishment and hence we perceive the ﬁbres of all plants more ﬁrmly matted around the interior of a soft-burned porous pot and having a more healthy appearance, than in a smooth, hard-burned pot, close in its texture. From these facts, we may naturally conclude, that if water-pipes and pipe-tiles were made with qualities the reverse required in garden-pots, no obstruction would occur either from earthy deposits, incrustation, or the roots of plants.
I hope that what I have said on the best modes of preparing clays will induce landowners to be on their guard in this important process and I venture to affirm that many of the deﬁciencies of pipe-tiles and tiles may be ascribed to the preparatory process being carelessly performed.