:Book IV. GATES APPROPRIATE TO AGRICULTURE. 



445 



2&47. 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 constructing the walls of larm-houses and oltices, and for 

 subdividing houses into different apartments. When either the outside walls, or the inside divisions of a 

 house are made of these materials, the custom is, to take a small quantity of straw, and incorporate it with 

 a sufficient prot>ortion of clay; the straw in this case answers the same purpose as hair in plaster- lime. 

 When a sufficient number of these are made, the work is begun by laying a stratum at the bottom of the 

 intended wall ; when this is done, and the different pieces firmly kneeded, or wrought together with the 

 hand, a flat deal board is applied on each side, which being properly pressed, and rubbed against the build- 

 ing in a horizontal direction, not only serves to consolidate the work, but gives it a degree of smoothness 

 and uniformity ; successive stratums are added, till the wall is raised to the intended height, taking care 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. 



2848. Rammed earthy or enpisS 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 civilization. In constructing them the earth is previously pounded, in order to 

 crumble any stones therein ; clay is added thereto 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, and 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. It is strongly 

 beaten ; and this method is continued successively, till the wall is compl eted. 



2849. Stainped earth tvalls are the invention of Francois 

 Cointeraux. Earth prepared in the same manner as for rammed 

 walls, is put into a mould or box of any size, generally that of the pro- 

 posed wall's thickness in width, one or two feet long, and about 

 one foot high [fig. 395 a). The mould is a strong oaken or iron 

 box, and the earth being placed in it, is compressed either by the ac- 

 tion of a press acted on by a lever or screw, or a stamping engine 395 

 similar to the pile driver, or great forge hammer. The stone, or 

 solid body of earth (6), 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. 



Chap. V. 

 Of Gates appropriate to Agriculture. 



2850. The gate may I)e considered as a moveable 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. 



2851. With respect to co7isfrMC^io7i the great object is, to combine strength with light- 

 ness. The absolute strength of materials depends on their hardness and tenacity. A 

 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, re- 



S^i 



sorted to by the employment of slips or bars, 

 disposed and joined together on mechanical 

 principles. These principles, applied to car- 

 pentry, direct the use of what aie called ties 

 and strutts, in the judicious composition of 

 which, as far as construction is concerned, 

 consists the whole art of carpentry. A tie (Jig. 

 396 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 abso- 

 lute strength of the gate ; and on their light- 

 ness, and on the general form of the gate, depends its adaptation for opening and shutting 

 by means of hinges. 



