should never be used, as from the moment it is finished its decay commences, and pains or attention will be able to keep it in repair after it has stood two or three years. 3071. Stone and turf walls are also very common in many situations, where better and more durable ones could be made at equal, perhaps less, expense. In many instances, however, they are employed from necessity, where lime is either very dear, or not obtainable at any price.

3072. Mud walls, with a mixture of straw, were formerly frequent in many places, not only for surrounding small enclosures and stack-yards, but also for the walls of farm-houses and offices, and for subdividing houses into different apartments. When either the outside walls, or the inside divisions of a house, are to be made of these materials, the custom is, to take a small quantity of straw, and incorporate it with a sufficient proportion of clay; the straw in this case answers the same purpose as hair in limeplaster. When a sufficient number of small masses are made, the work is begun by laying a stratum at the bottom of the intended wall; this being done, and the different pieces firmly kneaded or worked together with the hand, a flat deal board is applied on each side, which, being properly pressed and rubbed against the building in a horizontal direction, not only serves to consolidate the work, but gives it a degree of smoothness and uniformity; successive strata are added, till the wall is raised to the intended height, care being taken to taper it gradually upwards. Walls made in this way, if properly constructed, will last for many years; and, if dashed or harled with lime at a proper season of the year, will have an appearance no way inferior to such as are made with stone and lime; along with this addition to their appearance, the harling or dashing with lime, if properly done, will, by preventing the access of moisture, render them much more durable.

3073. Rammed earth, or en pisé, walls are very common in France, both as fences and walls for buildings. They have been described at great length in the Communications to the Board of Agriculture, and in other works, and tried in various parts of this country with tolerable success, though they are by no means suited either to our moist climate, or degree of civilisation. In constructing them the earth is previously pounded, in order to crumble any stones therein; clay is added in a small quantity, about one eighth part. It is all beaten and mixed up together by repeated blows with a mallet about ten inches broad, ten or fifteen inches long, and two inches thick. The earth being thus prepared, and slightly wetted, the foundation of the wall is dug. This is laid with stone; and, when it is about one foot high above the surface of the ground, planks are arranged on each side, and the space between filled with the earth intended for the wall, which is strongly beaten. This method is continued successively, till the wall is completed. 3074. Stamped earth walls are the invention of François Cointeraux. Earth prepared

491

b

in the same manner as for rammed walls, is put into a mould or box of any size, generally that of the proposed wall's thickness in width, one or two feet long, and about one foot high. (fig. 491. a) The mould is a strong oaken or iron box, and the earth being placed in it, is compressed either by the action of a press acted on by a lever or screw, or a stamping-engine similar to the pile-driver or great forge-hammer. The stone, or solid body of earth (b), thus acquired, is then used in the same way as common hewn stone, and either bedded or merely jointed with lime-mortar; it is then washed or harled, both for effect and duration. Various machines for forming bricks and stones for the ordinary purposes of building fence walls, and sheds, and other buildings of one story high, may be

found in the eighth and ninth volumes of the Mechanic's Magazine.

CHAP. V.

Gates and Bridges appropriate to Agriculture.

3075. The gate may be considered as a movable part of a fence, or as a frame of timber, or iron, readily moved, and calculated to give a convenient inlet and outlet to enclosures. Gates may be considered in regard to the principles of their construction and fixing; the materials of which they are made; and their different kinds.

A

3076. With respect to construction, the great object is to combine strength with lightness. The absolute strength of materials depends on their hardness and tenacity. gate, therefore, consisting of one solid plate of wood or iron, would seem to require most force to break or tear it in pieces: but this would not be consistent with lightness and economy, and in the use of such a gate it would be found to open and shut with more difficulty than one less strong. The skeleton of a plate of wood or iron is, therefore, resorted to by the employment of slips or bars, disposed and joined together on mechanical principles. These principles, applied to carpentry, direct the use of what are called ties and strutts, in the judicious composition of which, as far as construction is concerned, consists the whole art of carpentry. A tie (fig. 492. a) is a bar, or piece of timber, so placed in a structure as to resist a drawing or twisting power; a strutt (b) is one so placed as to resist weight, or whatever has a tendency to press or crush. The horizontal bars of

a gate are all ties; the diagonal and perpendicular ones strutts. On the judicious combination of these ties and strutts depends the absolute strength of the gate; and on their lightness, and on the general form of the gate, depends its adaptation for opening and shutting by means of hinges.

3077. The construction of a gate best adapted for opening and shutting is next to be considered. All gates, after being hung, have from their gravitation a tendency to deviate from their original position, to sink at the head or falling post, and thus no longer to open and shut freely. If the construction and hanging of the gate were perfect, this could not possibly take place; but as the least degree of laxity in trussing the gate, or want of firmness in fixing the post in the ground, will occasion, after frequent use, a sensible depression at the head, it becomes requisite either to guard against it as much as possible in the first construction, or to have a provision in the design of the upper hinge (fig. 493.) for rectifying the deviations as they take place.

492

с

3078. In order to understand the construction best calculated to resist depression, suppose a gate hung, and resting on its heel (fig. 492.c) acting as a strutt, and maintained there by its upper hinge (d) acting as a tie, then the bottom rail of the gate considered as representing the whole, becomes a lever of the second kind, in which the prop is at one end (c), the power at the other (g), and the weight placed between them in the line of the centre of gravity of the gate (). Now, as two equal forces, to hold each other in equilibrium, must act in the same direction, it follows that the power acting at the end of the lever (g) will have most influence when exerted at right angles to it in the line (ge); but as this cannot be accomplished in a gate where the power must be applied obliquely, it follows, that a large angle becomes requisite; that the greater the angle, the greater the power, or, in other words, the less the strain on the construction of the gate, or the less the tendency to sink at the head. The half of the right angle (c é g) seems a reasonable limit, by which, if the power requisite to hold the weight in equilibrium, when acting at a right angle, be as the side of a square of the length of the lower bar of the gate (gc), then the power requisite to effect the same end, when acting at an angle of 45 degrees, is as the diagonal to this square (gh). By changing the square to a parallelogram, the rela advantages and disadvantages will be rendered more

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tive proportions will still be the same, and the

obvious.

3079. Waistell and Parker have paid great attention to the construction of gates for many years. More than fifty years ago, Waistell circulated among his friends plans for ornamental gates with semioval and semicircular braces, and such gates (fig. 496.) have now become general. Parker has directed his principal attention to the hangings and fastenings of gates; and his forms of latches, hinges, &c., 23 well as his turnpike-gates (fig. 495.), are also very general. The head (fig. 493. a) and heel (b) are to

3080. The construction of the gate is thus given by Waistell.

The other four bars, and the four braces

The dimensions in column under A are taken on the face of the gate; those in the column under B are taken in the direction of its thickness. Narrow and thick bars, when braced as in this design, are stronger than broad and thin ones, containing the same quantity of timber, and they also oppose a less surface to the

wind. The two points in the heel of the gate, to which the thimbles are fastened, may be considered as firm or fixed points. From these points, viz. 1 and 2, (fig. 494.) two braces proceed to 4 and 3 in the middle d the bottom and top bars, and being there secured, these become fixed points, and from these two points, viz 4 and 3, two braces proceed to 5 and 6, fixing those points. The gate is thus doubly braced, viz. from the top of the heel to the top of the head, by means of the braces 1, 4, and 4, 5; and from the bottom of the heel to the bottom of the head, by means of the braces, 2, 3, and 3, 6. On each side of the gate are twe braces, and those parallel to each other. The brace proceeding from the bottom of the heel of the gate, and that which is parallel to it, as also the bottom bar, are all strained in the way of compression; and the brace proceeding from the top of the heel, and the other brace which is parallel to it, and also the top bar, are all strained in the way of extension. The strains in this gate being none of them transverse, but all longitudinal, it would support a vast weight at its head, without having its form altered. All the braces serve the double purpose of keeping the gate in its due form, and of shortening the bearings of the bars, and strengthening them. Few gates have less timber in their braces, and, perhaps, in no other way can a gate be so firmly braced with so small a quantity of timber. At 3, 4, 7, and 8, two braces and a bar of the gate are firmly screwed together, by means of iron pins and screw-nuts. At the other points, where only one brace crosses a bar, common gate-nails are used. To resist the pressure of heavy cattle, a bar, or board, about six inches broad and one inch and a quarter thick, should be laid with its broad side upon the top bar (see section at C), and fixed thereto by means of the ends of the braces in the middle, and by the head and heel of the gate at the two ends of it. This board will, in this position, resist about the same hori. zontal pressure as a thick top bar three inches and a half square, although it contains little more than half the timber. It is necessary that the lower bars of a field or fold gate should be sufficiently close to prevent pigs, lambs, &c. from getting through; but the distances between the upper bars should be greater, that it may be constructed without either unnecessary wood or weight. In order, therefore, to arrange the bars so that the increase of their distances may be uniform, the following rule may be serviceable :-"The height between the bottom bar and the top bar being given, the position of the other four bars, or for any other number of bars, may be found; thus, suppose a o the given height, to which the width of an inter

mediate bar is added, one half on the top bar, and the other half on the bot. tom bar. One bar must always be exactly in the middle between these two, as at c, to which the braces, at their crossing, are to be bolted. In this design another bar is required between a and c, and two bars between c and b; that is, the whole distance, ab, is to be divided into five parts, in a regular progression to each other. Draw any line, a d, and from

set off, of any length, five equal divisions; from the second division draw a line through c, in the direc tion e, and from the fifth division draw a line through b, also in the direction e, where the two lines will cross; then from the division 1, 3,

and 4, draw other lines to e, the point last found, and where these lines cross, the line a b will be the position of the centres of the breadth of the other bars. From the centre of each bar, thus found, mark off half the length of each mortice, and whether the rails be of the same width as the mortices, or tenoned with an equal shoulder on their upper and lower edges, they will be all in a regular progression; or, in numbers, if the distance a b be divided into 110 equal parts;

The progressive differences between the distances being 2, 3, 4, and 5, the three first being equal to the two last, and the whole equal to one hundred and ten. But if adjusted in the proportion of the following numbers, the whole height A B, being divided into thirty equal parts, the bars at the bottom of the gate will be a little closer:

These numbers have one as a common difference. If these rails have shoulders, and are pinned so as to draw them close to the head and heel, they will be better than without shoulders. The pins should not be exactly in the middle of the breadth of the head and heel, but nearer the inner edge, that the piece of wood between the pin-hole and the end of the rails may not be so liable to split out.

3081. "On the hanging of gates. When gates are hung to open one way only, their heels and heads generally rest against the hanging and falling post, and are about six inches longer than the opening; but when they are hung according to this design, gates may be made one foot shorter, or six inches less than the opening; and, consequently, they are lighter, stronger, and less expensive. The heel may be three inches and a half from the hanging-post, and the head two inches and a half from the falling post. When the two hooks in the hanging-post are placed in the same perpendicular line, a gate, like a door, will rest in any position to which it may be opened; but in order that a gate may shut itself when thrown open, the hook must not be in the same perpendicular line, and the farther they are out of it, the greater will be the force with which the gate will close. The following is a method of fixing the hooks and eyes, or thimbles, to answer this purpose:-Supposing the hanging-post to be set perpendicular, and that one side or face of the gate is intended to be in a line with one side of the posts, as shown in the engraving, the centre of the upper hook may be two inches and a half from the inside, and one inch from the face of the post. The centre of the eye, or thimble, for the upper hook, may be one inch from the heel, and one inch from the face of the gate. The centre of the lower hook may be an inch and a half from the inside, and half an inch from the face of the post. The eye for the lower hook may be two inches from the heel, and half an inch from the face, of the gate. The best way of fixing the hooks to wooden posts, is to have shoulders to keep them at the proper distance, and a screw and nut on the end which is to go into the post, to which they should be tightly screwed. The eyes should have straps to go on each side of the heel, and along the bottom and top rails of the gate. The straps for the bottom eye may be about six inches long, with two holes for bolts; one of the bolts to go through the middle of the heel, and the other through the bottom rail and brace. The straps to the top eye may be nine inches long, with three holes for bolts. Blocks being fitted in between the straps and the bars, the nuts are then screwed on the bolts. Eyes of this description, which answered very well, have been made of cast iron; the pins and screws of the hooks were of wrought iron, the other part cast. The position of a plane passing through the centre of each hook, is shown in the engraving (fig 494.), by the dotted line A B on the plan. If the gate was opened to B, it

would be at its highest elevation, and would have a tendency to fall either way until it arrives at A, when the head will be at its lowest descent. If the gate be shut, the spur and catch prevent the head from falling to its lowest position; but the tendency it has to fall to A, is designed to assist in keeping the gate closed. The iron-work of the gate ought at least to be painted. If the whole of the gate be painted, the appearance is greatly improved; and if, when painted, the wood be quite dry, it will be likely to last longer. Gates, in close situations under trees, although painted, will sooner decay than gates not painted, in open and more exposed grounds; and this circumstance has, perhaps, induced some persons to conclude that the paint, instead of the situation under trees, was injurious to the gates."

3082. Parker's compensation hinge for gates which are much in use (fig. 495.) is an excellent corrective

to their falling; all that is necessary, when the gate sinks at the head, is to screw it up by the nut (a) till it regains its original position. For road and farm yard gates the hinges are valuable parts of the construction.

3083. A gate should be so hung as to have two falls; one to the hanging-post, to make it catch,

and the other to a point at right angle with the gateway, so as to keep it fully open. To effect this purpose, having set the post perpendicular, let a plumb-line be drawn upon it: on this line, at a proper height, place the hook, so that it may project three inches and a half from the face of the post; and at a con. venient distance below this place the lower hook an inch and a half to one side of the perpendicular line, and projecting two inches from the face of the post; then place the top loop or eye two inches from the face of the hanging style, and the bottom loop three inches and a half: thus hung, the gate will have a tendency to shut in every position. A gate so hung will have a tendency to shut in every position: because if the weight of the gate be represented by a diagonal line from the heel to the head, this, by the resolution of forces, is resolvable into other two lines, one perpendicular, and the other horizontal; the former representing that part of the weight which presses in a perpendicular position, and the latter that part of the weight which presses in a horizontal direction, and gives the gate a tendency to shut. Northumb. Rep. 63.)

3084. Gales are generally constructed of timber, and whatever kind may be used it is essential that it be well seasoned, as, without attention in this respect, they are soon deranged in their structure by the heat of the sun: they should also be well and correctly put together. Oak is undoubtedly the best sort of wood for the purpose, where durability is the object; though some of the lighter kinds of woods, as deal, willow, &c. will often last a great length of time, as, from their lightness, they are not so apt to destroy themselves. The lighter gates are made towards the head or opening part the better, provided they are sufficiently strong for the purpose they are to serve; and on this account the top bars may, in many cases, as where horses are to be kept, be left considerably stronger than the others. If this is not done, they are liable to be broken by the animals rubbing their necks upon them, except where they are made very high. Gates are generally made eight and a half or nine feet in width, and from five to six feet in height; the bars being three or four feet broad, and five or six in number. particular instances a smaller bar is introduced between the two lower ones, in order to prevent small animals getting through.

In

3085. Iron, both hammered and cast metal, has long been in use for ornamental gates (fig. 496.), and has lately come into use in some districts for field gates. Their eligibility

496

AU

must depend on their price and durability with relation to wood. At the ordinary prices of wrought iron and oak, they will be found of doubtful economy; cast-iron gates are too heavy, and too liable to be broken, for agricultural purposes.

3086, The posts or pillars to which gates are attached should, in all convenient cases, be formed of stone; as this material, when hewn and properly constructed, will last for ages. When formed of wood, oak and larch are the best sorts. The latter, where suit

able, should be used without removing the bark, which has been found to add greatly to their durability. In some places it is customary to plant trees for gate-posts, and after they have attained a certain size and thickness, to cut them over about ten feet above the surface: where the trees thrive, they form the most durable of all gate-posts in many instances, however, they fail, and much trouble is necessary to repair the defect. Where the posts are made of dead timber, they should always be strong, and the wood well prepared: that part which is let into the earth should also be defended, by dipping it in coarse oil, or giving it a coat of pyrolignous liquor; and all that is above ground exposed to the action of the weather, should be well covered with one or two good coats of oil-paint. The expense of this preparation is but trifling, while the benefit is very great.

3087. The substance of a gate-post, according to Parker, should be from eight to ten inches square, or for very heavy gates a foot square would not be too large. If inade of still larger size, it is better. The steadiness of a gate-post, he says, depends in a great measure upon the depth to which it is set in the ground, which ought to be nearly equal to its height. Five or six feet are, in general, fully sufficient: but the posts may be kept in their places by a strong frame-work placed under the ground, extending between the posts.

497
b

3088. The fastenings of gates, it is observed by Parker (Essay, &c. 1816.), are as various as the blacksmiths who construct them. The subject occupied his attention in connection with the hanging of gates, and he has introduced various improved forms. One of the most secure (fig. 497.) is a spring-latch (a), opened by a lever (b) which works in a groove in the upper bar of the gate, and therefore cannot be rubbed open by cattle, while, by means of a knob at the end of the lever, and rising up against the top of the upright bar (c), so that cattle cannot touch it, it is very easily opened by persons on horseback with or without a stick or whip.

3089. A simple, economical, and effective spring-latch consists of a bolt (fig. 498 a.), which is loose, and

plays freely in two morticed openings in the upright bars, and is kept in place by a spring (b). The gate may be shut from either side, when the bar, striking against the projection (c) on the falling-post, is pushed back, till, arriving at the mortice (e), the spring (b) forces it in, and the gate is shut securely. Such a gate is easily opened by a rider. This is a good latch for the common field gates of a farm.

3090. For gates of an ornamental kind, Parker says, he does not know a better latch than the crooked lever (fig. 499.) now in com

mon use.

3091. The reversed latch (fig. 500.) is one of the latest improvements in this department, and is par

500

ticularly suitable for the gates in a gentleman's park. On the edge of the head of the gate a pin (a) is screwed; and on the falling post a plate containing two latches (be) turning on pivots. Whichever way the gate is opened, if left to shut itself, or if shut by force, it easily passes within the one latch, and is retained between that and the other. Taking it altogether, this is one of the cheapest and best field-gate latches. Where a gate opens only on one side, the latch plate may be made of one half the size, and with only one of the latches, according to the side on which the gate opens. A contrivance of this sort is in use at some of the pleasure-ground gates at Bretton Hall, near Barnsley, Yorkshire, and is found very efficacious and satisfactory. There are also some very handsome iron gates at that residence, which, with the latch stopper alluded to, will be found figured and described in the Gardener's Magazine, vols. vi. and vii.

3092. Gates are of different kinds (figs. 501. and 502.), according to the particular

custom of the district; but the principal sorts made use of are, the swing gate, the folding gate, the slip-bar gate, and the wicket and turn-about gate.

3093. The improved swing gate of the northern counties is well adapted for agricultural purposes. There is a projection on the forepart of the hanging style, which

rises nine inches, and on which the lower end of the diagonal bar, passing upwards, rests; there is also a diagonal bar through which the three middle horizontal bars pass. It is found to be a very strong and durable gate, and its construction, hanging, and principle of operation, are well understood among the country carpenters and hedgers of those parts.