Rum in chimneys, method of ing. It is well known, that the inner parts of chimneys easily take fire ; the soot that kindles therein emits a greater flame, according as the tunnel is more elevated, because the current of air feeds the fire. If this current could therefore be suppressed, the fire would soon be ex tinguished. In order to this, some dis charge a pistol into the chimney, which produces no effect. 'Water thrown into the chimney at the top is equally useless, because it comes down through the mid dle of the tunnel, and not along the sides. It would be more advisable to stop, with a wet blanket, the upper orifice of the tunnel ; but the surest and readiest me thod is, to apply the blanket either to the throat of the chimney, or over the whole front of the fire-place. If there happens to be a chimney-board or a register, no thing can be so effectual as to apply them immediately ; and having by that means stopped the draught of ail- from below, the burning soot will be put out as readily and as completely as a candle is put out by an extinguisher, which acts exactly upon the same principle. Mr. Smart's machine for sweeping chimneys is ad mirably adapted to extinguish those that are on fire. See Crnamcv-s-weeping.
Firm, securing buildings against. Dr. Hales proposes to check theprogress of fires by covering the floors of the adjoin ing rooms with earth. The proposal is founded on an experiment which he made with a fir board half an inch thick, part of which he covered with an inch depth of damp garden-mould, and then lighted a fire on the surface of the mould ; though the fire was kept up by blowing, it was two hours before the board was burnt through, and the earth prevented it from flaming. The thicker the earth is laid on the floors, the better : however, Dr. Hales apprehends that the depth of an inch will generally be sufficient : and he recommends to lay a deeper covering on the stairs, because the fire commonly as cends by them with the greateSt velocity. Mr. David Hartley made several trials in the years 1775 and 1776, in order to evince the efficacy of 3• method which he had invented for restraining the spread of fire in buildings. For this purpose, thin iron plates were well nailed to the tops of the joists, &c. the edges of the sides and ends being lapped over, folded together, and hammered close. Parti tions, stairs, and floors, may be defended in the same manner ; and plates applied to one side have been found sufficient. The plates are so thin as not to prevent the floor from being nailed on the joists, in the same manner as if this preventive was not used ; they are kept from rust by being painted or varnished with oil and turpentine. The expense of this addition, when extending through a whole building, is reckoned at about five per cent. Mr. Hartley had a patent for this invention, and parliament voted a, sum of money towards defraying the expense of his numerous experiments. The same preservative may also be ap plied to ships, furniture, &c. Mr, Hart ley's patent has long since expired. Earl Stanhope also discovered and published a very simple and effectual method of securing every kind of building against fire. This method he has divided into three parts, viz. under-flooring, extra lathing, and inter•securing The method of under-flooring is either single or double. In single under-flooring, a com mon strong lath of oak or fir, about one fourth of an inch thick, should be nailed against each side of every joist, and of every main timber supporting the floor which is to be secured. Other similar laths are then to be nailed along the whole length of the joists, with their ends butting against each other. The top of each of these laths or fillets ought to be at 1.1 inch below the top of the joists or timbers against which they are hailed; and they will thus form a sort of small ledge on each side of -alt the joists. These fillets are to be well bedded in a rough plaster hereafter men tioned, when they are nailed on, so that there may be no interval between them and ; and the same' plaster ought to be spread with a trowel upon the tops of all the fillets, and along the sides of that part of the joists which is between the top of the fillets and the upper edge of the joists. In order to
fill up the intervals between the joists that support the floor, short pieces of common laths, whose length is equal to the width of these intervals, should be laid in the contrary direction to the joists, and close together in a row, so as to touch one another ; their ends must rest upon the fillets, and they ought to be well bedded in the rough plaster, but are not to be fastened with nails. They must then he covered with one thick coat of the rough plaster, which is to be spread over them to the level of the tops of the joists; and -in a day or two this plaster slfould over close to the sides of the joists, Without covering the tops of the joists with it. In the me thod of double-flooring, the fillets and short pieces of laths are applied in the manner already described ; but the coat of rough plaster ought to be little more than half as thick as that in the former. method. Whilst this rough plaster is laid on, some more of the short pieces of laths above-mentioned must be laid in the intervals, between the joists upon the first coat, and be dipped deep in it. They should be laid as close as pos sible to each other, and in the same direction with the first layer of short laths. Over this second layer of short laths there must be spread another coat of rough plaster, which should be trow elled level with the tops of the joists without rising above theth. The rough plaster may be made of coarse lime and hair; or, instead of hair, hay chop ped to about three inches in length may be substituted with advantage. One Measure of common rough sand, two measures of slacked lime, and three measures of chopped hay, will form in general a very good proportion, when sufficiently beaten up together in the manner of common mortar. The hay should be put in after the two other ingredients are well beaten up together with Water. This plaster should be nude stiff; and when the flodring-boards are required to be laid down very soon, a fourth or fifth part of quick-lime in pow der, formed by dropping a small quan tity of water on the limestone a little while before it is used, and well mixed with this rough plaster, will cause it to dry very fast. If any cracks appear in the rough plaster-work near the joist when it is thoroughly dry, they ought to be closed by washing them' over with a brush wet with mortar-wash ; this wash may be prepared by putting two measures of quicklime and one of com mon sand in a pail, and stirring the mix ture with water, till the water becomes of the consistence of a thin jelly. Be fore the flooring-boards are laid, a small quantity of very dry common sand should be strewed over the plaster-work, and struck smooth with a hollow rule, moved in the direction of the joists, so that it may lie rounding between each pair of joists. The plaster-work and sand should be perfectly dry before the boards are laid, for fear of the dry-rot. The, me thod of under-flooring may be success fully applied to a wooden staircase ; but no sand is to be laid upon the rough plaster-work. The method of extra-lath ing may be applied to ceiling joists, to sloping roofs, and to wooden partitions. The third method, which is that of in ter-securing, is very similar to that of under-flooring; but no sand is after wards to be laid upon it. Inter-securing is applicable to the same parts of a building as the method of extra-lathing, but it is seldom necessary. 'The author of this invention made several experi ments, in order to demonstrate the effi cacy of these methods. In most houses it is only necessary to secure the floors ; and the extra expense of under-flooring, including all materials, was at that time only about ninepence per square yard, and with the use of quicklime a little mote. The extra of extra-lath ing is no more than sixpente per square yard for the timber, side walls and parti tions; but for the ceiling about nine pence per square yard. But in most houses no extra-lathing is necessary.