LATH, a slip of wood used in plastering, tiling, and slating. These are what Festus calls ambrices ; in other Latin writers they are denominated templa ; and by Gregory of Tours, liyaturcc.
In plastering, the narrower the laths are, the better they are for the purpose, so that they be of sufficient breadth to hold the nails, as the more the number of interstices is increased, the more readily will the lime or stuff hang ; and the thicker they are, the better will they be adapted to resist violence; but then they would be much more expen sive. The laths are generally made of fir, in three, four, and five feet lengths, but may be reduced to the standard of five feet. Laths are single or double ; the latter are gene rally about three-eighths of an inch thick, and the former barely one quarter, and about an inch broad. Laths are sold in bundles; the three-feet are eight score to the bundle, four-feet, six score, and the five-feet, five score.
The lath for plain tiling is the same as that used in plas tering. Laths are also distinguished into heart and sap laths ; the fimner should always be used in plain tiling, and the latter, of an inferior quality, are most frequently used by the plasterer. lIeart-uf-uak laths, by the statute Edw. Ill.
should be one inch in breadth, and half an inch in thickness; but now, though their breadth be an inch, their thickness to seldom more than one quarter of an inch ; so that two, as they are now made, are but equal to one. According to the same statute, pantile laths are nine or ten feet long, three quarters of an inch thick, and one and a half inch broad, and should be made of the best yellow deal : the bundle consists of twelve such laths. A square of plain tiling will require a bundle of laths, more or less, according to the pitch. The distance of laying laths one from another is various, differing more in some places than in others ; but three and a half, or tour inches, are usual distances, with a counter-lath between rafter and rafter ; but if the rafters stand at wide intervals, two counter-laths will be necessary. Laths are employed for various other purposes besides plastering and tiling, as in filleting for sustaining the ends of boards; in naked flooring and roofing, for furring up the surfaces; and in every kind of small work, Nvhere the dimensions of the parts do not exceed the scantling of laths.
In lathing for plastering, it is too frequent a custom to lap the ends of the laths upon each other, where they terminate upon a quarter or batten, to save the trouble of cutting them ; but though this practice saves a row of nails, it leaves only a quarter of an inch for plaster, and if the laths are very crooked, as they frequently are, there will be no space what ever left to straighten the plaster ; the finished surface must, therefore, be rounded, contrary to the intention and to the good effect of the work ; but if the ends are to be laid upon each other, they should be thinned at the lapping out to nothing at the extremity, or otherwise they should be cut to exact lengths.
Laths should be as evenly split as possible ; those that are very crooked should not be used, or the crooked part should be cut out; and such as have a short con cavity un the one side, and a convexity on the other, not very prominent, should be placed with the concave side outwards. The following is the method of splitting laths: the lath-cleavers having cut their timber into lengths, they cleave each piece with wedges into eight, twelve or sixteen pieces, according to the scantling of the timber: the pieces thus cloven are called bolts ; then in the direction of the feltgrain, with their dowl-axe, into sizes for the breadth of the laths : this operation they call felting ; and, lastly with their chit, they cleave them into thicknesses by the quarter-grain.
In the United States of America, machinery has been employed for rending as well as for sawing out laths : there is nothing original in the latter operation, but there is appa rently something worthy of notice by our countrymen in the annexed report of American patents, which we extract from tho Franklin Journal of Philadelphia.
In Rice's machine, "a stock is fixed in a frame, in which it slides freely backward and forward ; it is moved by a cog wheel, which works in cogs on one side of the stuck, in the manner of a rack and pinion. A knife, is fixed upon the stock, and the timber to be cut into laths, &c., is fixed in frame, and is made to bear against the stock and the lath is cut by the traversing motion of the stock. The knife, it is said, many have a double edge, so as to cut a lath by the forward and backward motion." Lynch's machine " consists of a long plank, which operates as a plane stock ; this plank is made to slide upon its edge between upright standards upon a firm platform ; a wide iron like a plane-iron, is fixed so as to cut on one face of this plank much in the manner of the cutters of some single machines ; the throat of the plane, if we may so call it, has other cutters standing at right angles with the first cutter, and at such distances apart as to reduce the laths to a proper width. The cutter plank is made to traverse by means of a pitman at one end, operated upon by any suitable power.
LArn-Buiess are bricks made much longer than the ordinary sort, and used instead of laths for drying malt upon, for which purpose they are extremely convenient, as not being liable to catch fire, and retaining the heat ranch longer than those made of wood, so that a very small dire is suffi cient after they are once heated.