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more is necessary to ascertain the quantity of will be rendered equable in every part of their water they will deliver, than to calculate the solid revolution. From the formation of this machine, or cubical contents of that part of the barrel in when one of these flaps is brought by the revoluwhich the vacuum is produced, and to reduce this tion of the internal cylinder between itself and to some standard measure, and then to multiply the external one, it will be pressed down close this by the number of strokes made in a given and will shut, but, as the inner cylinder moves, time; thus, if a pump is nine inches diameter, and it will be carried into a continually widening makes an effective stroke of about eighteen inches, space until it arrives at d, opposite to the lastsuch a cylinder will be found to contain about mentioned situation, when the cavity formed 1134 cubic inches; and, as 282 cubic inches make between it and the smaller and larger cylinder a gallon, so four gallons will be equal to 1128 will have so far increased as to form a vacuum cubic inches, consequently such a barrel will which is filled with water by the feeding pipe e. contain and throw out rather more than four This cavity is no sooner so increased to its gallons at every stroke; and supposing this pump largest dimensions than it is diminished by a to make ten strokes in a minute, it would yield continuation of the revolution, in consequence of forty gallons in a minute, or sixty times that which the water, being pent up and squeezed into quantity in an hour, and so on. This rule ap- less compass, makes its escape by the delivering plies in every case, whether the water is sent to pipef; and, as each of the flaps performs the same a small or great elevation, because the piston operation in its turn, this pump affords a very cannot move without displacing the water in the equable and constant supply of water. The barrel; but a small allowance must be made for greatest difficulty in its construction is that of leakage or waste, because some water will con- keeping the sides of the flaps so packed as to stantly pass the piston and escape, or be other- maintain a perfect contact with the sides of the wise lost and wasted.

larger cylinder without unnecessary friction, a This mode of calculation, as before observed, fault which equally holds good in Mr. Bramah's only applies to such pumps as have cylindrical fire-engine, in all excentric pumps, and in all the working barrels and pistons; but sometimes rotatory steam-engines that have yet been inpumps are otherwise constructed, of which the vented. The excentric pump is of the lift and fre-engine of the late Mr. Bramah, and the exe- force variety, since it will deliver water to an cutric pump are instances. In the former of indefinite height above its working cylinders. these contrivances, the working barrel, instead In order to determine the force or power necesof being an entire cylinder, is a semi-cylinder, sary to work a pump of any description, the and lies horizontally, while the place of a piston height to which the water is to be raised must is supplied by a parallelogram of the same radius always be taken into account; for this height and length as the semi-cylinder, moving by an multiplied into the area of the piston, and reiron bar passing through its axis and properly duced to any of the usual denominations of weight, packed at its exterior edges. This parallelogram will give the amount of resistance to be overcome is made to vibrate through about 170° by its (friction of the pump only excepted). The size handles, while its outer edges keep in contact of the pipe containing the water is quite immawith the interior surface and ends of the semi- terial, provided it be large enough to prevent cylinder, and two feeding and two delivering friction and an unnatural velocity in the water; and valves are placed upon the flat top or covering the entire perpendicular height from the surface of the whole. This pump, therefore, in effect is of the water raised to the point where it is delivered, the same as that of N. De la Hire, though whether occupied by suction or feeding pipe, or quite different in form, and its mode of opera- delivering pipe from a forcing pump, must be tion is nearly allied to the excentric pump, a added together and considered as the height of section of which is shown at fig. 5, HYDRAULICS. the lift; so that if a lift and force pump of four It consists of a hollow drum or cylinder of metal inches diameter in the working barret has teu ad, in the interior of which a solid cylinder b, of feet of three-inch suction pipe below its piston, the same length, but of only half the diameter or and twenty feet of two-inch delivering pipe (inthereabouts, is made to revolve by its axles pass- cluding the length of the working barrel) about ing through water-tight stuffing-boxes in the sides it, the column to be lifted will be equal to thirty of the larger and exterior cylinders. The internal feet of four-inch pipe filled with water. The cylinder does not revolve in the centre of the contents in gallons of thirty feet of four-inch pipe larger, but is so placed that one of its convex must therefore be found, and, as each gallon of exterior edges may come into close contact with water weighs about 10-2 pounds, the weight or some one part of the concave or internal surface load upon the pump will be immediately found, of the larger cylinder, as shown in the figure, to which must be added from one-tenth to oneand the circular exterior surface of the small sixth, according to the construction of the pump, cylinder is equipped with four metal flaps or for friction. The load upon an excentric or any valves, C, c, c, c, turning on hinges, and partaking other pump may be found by the same rule if the of its own curvature, so that when they are shut effective horizontal area of the piston, or its subdown or closed they form no projections, but stitute be found, and this be, in like manner, appear as parts of the same cylinder. These multiplied into the height of the lift. flaps are made to open either by springs placed The Society of Arts voted a silver medal and underneath them, or, what is still better, by two twenty guineas to Mr. Furst, in consideration of cross wires, sliding through the internal cylinder the utility of a contrivance produced by him, in such manner that they may cross each other and of which trial was made, for increasing the exactly in its centre, by which their operation effect of engines for extinguishing fires : a com

plete model remains in the Repository of the Zachary Greyl. He contrived certain engines, Society, of which the following is a short descrip- easily manageable, which he proved to be of tion :-From a platform rises an upright pole or sufficient efficacy, and offered to discover the mast of such height as may be judged necessary; secret by which they were contrived, for a large up this pole or mast slides a gaft, and along the premium given either from the crown, or raised upright pole and gaft the leather hose from the by a subscription of private persons. The seengine is conveyed; at the extremity of the gaft cret was this: a wooden vessel was provided the branch of the engine projects; towards this holding a very considerable quantity of water; extremity is fixed an iron frame whence hang in the centre of this there was fixed a case made two chains, and from them ropes serving to give of iron plates, and filled with gunpowder; from an horizontal direction to the branch, whilst this vessel, to the head of the larger vessel conother ropes running through proper pullies, and taining the water, there proceeded a tube or being thus conveyed down the mast, serve also pipe, which might convey the fire to the gunto communicate a vertical motion to it; by these powder in the inner vsssel. This tube was filled means the branch or nose pipe of the engine is with a preparation easily taking fire, and quickly convered into the window of any room where burning away; and the manner of using the the fire more immediately rages, and the effect engine was to convey it into the room or buildof the water discharged therefrom applied in the ing where the fire was, with the power in the most efficacious manner to the extinguishing tube lighted. The consequence of this was, that of it.

the powder in the inner case soon took fire, and, Mr. Perkins's method of fastening the seams with a great explosion, burst the vessel to pieces, of hose for fire-engines, and connecting two or and dispersed the water every way: thus was more lengths together, consists in rivetting, in- the fire put out in an instant, though the room stead of sewing it; and in connecting the hose was flaming before in all parts at once. In our with a new modification of the swivel joints, in own country a chemist of the name of Godfrey, such a manner as not to contract the water way has brought forward similar machines which le at the joints. The first idea of rivetting hose called water-bombs. They were however so belongs to Messrs. Pinnock and Sellers, of Phi- very similar to Greyl's as to need no further deladelphia, and has been in successful practice scription, except that instead of water Godfrey for some years, but without the leathers being used a medicated liquor, probably sal-arnmoniac overlapped sufficiently. The method of con- and water. But though these machines will Decting the hose belongs to Mr. Perkins. The prevent great fires by a timely application, they advantage of rivetting over sewing is, that the will not extinguish them after they have reached seam lasts much longer, and is much tighter. a frightful height, and several houses are in The rivets, which should be made of copper, Hames. The foors must be standing, and acwill last four or five times longer than the best cess to the building safe, otherwise no person thread. If care is taken to have sufficient over can be supposed to approach neat enough to lap, the pressure of water against the overlap apply them in a proper manner. Every fire has acts as a valve to tighten the seam. It has been its beginning for the most part in some apartfound by experience, that the portion of hose ment; and, as soon as discovered, the family Dext the engine is much the most likely to burst, should immediately apply one or more of these especially when the water is carried perpen- machines, which will then fully answer the indicularly; to obviate this difficulty, the first, tention. In 1761 Mr. Godfrey's experiment for tbird, or fourth portions are double-rivetted. extinguishing fire, was tried in a house erected

When a rivet breaks, it is replaced by making for that purpose near Mary-le-bone. The then an opening in the seam of sufficient size to allow duke of York, prince William Henry, prince the hand to replace not only the broken rivet, Henry Frederic, and a great number of persons but the rivets taken out to enlarge the opening. of rank, gave their attendance on this singular After the rivets are fixed in the holes, they are occasion. The house, which was of brick, conrivetted by placing them on a flat bar of iron, sisted of three rooms one above another, a stairintroduced into the entrance of the hose, and case, chimney, lath and plaster ceilings, and a capable of being removed at pleasure. Copper kind of wainscotting round the rooms, of rough has been found to answer best. It is of such deal. Exactly at twelve o'clock the ground importance that the rivet and burr should be of room, and that of one pair of stairs, were set the same material, that it would not answer well on fire, by lighting the faggots and shavings laid to have the rivets of cast copper (they being an in there for that purpose. In about fifteen mialloy of tin and copper), and the burr of wrought nutes the wainscot of the under room copper. Tin rivets, with copper burrs, will com- thought to be sufficiently in flames, and three of pletely destroy the leather in a few months, the machines were thrown in ; 'which, by almost occasioned, undoubtedly, by the operation of immediate and sudden explosions instantaneously galvanism.

extinguished the flames, and the very smoke in Many have been the attempts to produce that apartment in a few minutes totally disapsome machine by means of which fires might be peared. By this time, the firemen, &c., who had more rapidly extinguished than by the common the care of throwing in the machines, gave an application of water. These machines have alarm that the stair-case had taken fire, and that been principally constructed with a view to ex- it was necessary directly to go to work upon the ploding, and thus driving the liquids more for- next room, which was accordingly done, and cibly to the fire. The first person who attempted with the same effect. The experiment however this with any tolerable degree of success was hitherto did not universally satisfy, in the last

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instance especially it was thought to be too has- rally be sufficient; and he recommends to lay a tily put in execution. For the sake of the expe- deeper covering on the stairs, because the fire riment, therefore, and to remove all manner of commonly ascends by them with the greatest doubt, Mr. Godfrey consented to a third expe- velocity. M. Hartley made several trials, in riment in the upper room, which was entirely of 1775 and 1776, to evince the efficacy of a mewood. The flames were now suffered to get to thod which he had invented for restraining the a considerable height, and even the window spreading of fire in buildings. For this purpose frames destroyed, before the machines were thin iron plates are well nailed to the tops of thrown in : which, however, answered exactly the joists, &c., the edges of the sides and ends as the former had done; and met with universal being lapped over, folded together, and hammered approbation.

close. Partitions, stairs, and floors may be deProfessor Palmer, of Brunswick, invented a fended in the same manner: and plates applied powder for extinguishing fire ; composed of equal to one side have been found sufficient

. The parts of sulphur and ochre, mixed with six plates are so thin as not to prevent the floor times their weight of vitriol. These ingredients from being nailed on the joists, in the same manare mixed, and the mass afterwards pulverized. ner as if this preventive were not used; they The powder is to be scattered over the places are kept from rust by being painted or varnished on fire; two ounces are sufficient for a surface with oil and turpentine. The expense of this of a foot square. When it is not possible to addition, when extending through a whole buildapproach the fames, cartridges may be made ing, is estimated at about five per cent. Mr. of it, and shot with a cross-bow against such Hartley obtained a patent for this invention, and parts of the building where the fire rages with parliament voted a sum of money towards dethe greatest violence.

fraying the expense of his numerous experiIn order to preserve timber from fire, the ments. The same preservative may also be professor directs, to rub it over with common applied to ships, furniture, &c. The late earl carpenter's glue, and then sprinkle the powder of Stanhope also published a very simple and over it, repeating the operation three or four effectual method of securing every kind of times, as the preceding layer becomes dry. If building against all danger of fire. This meyou wish to preserve cloth, paper, ropes, cables, thod he divided into three parts, viz. under&c., against fire, use water instead of glue, in flooring, extra-lathing, and inter-securing. 1. applying the powder.

The method of underflooring is either single or Mr. Knox of Gotenburg recommends to mix double. In a single underflooring, a common seventy-five gallons of water with ten quarts of strong lath of oak or fir, about one-fourth of an clay, ten quarts of vitriol, and ten quarts of inch thick, should be nailed against each side common salt; or a similar quantity of water, of every joist, and of every main timber supwith eighteen quarts of the strongest solution porting the floor, which is to be secured. Other of wood-ashes and eighteen quarts of fine clay similar laths are then to be nailed along the reduced to powder; or the same proportion of whole length of the joists, with their ends butwater, with fifteen quarts of red ochie, or the ting against each other. The top of each of residuum of aquafortis, and fifteen quarts of these laths or fillets ought to be at one inch common salt: or, lastly, to mix fifteen quarts of and a half below the top of the joists or timbers the strongest herring-pickle, and fifteen quarts against which they are nailed; and they will thus of red ochre, with seventy-five gallons of water. form a sort of small ledge on each side of all the All these different solutions, Mr. Knox remarks, joists. These fillets are to be well bedded in a are equally efficacious in extinguishing fire. rough plaster hereafter mentioned, when they

Another of the various inventions for extin- are nailed on, so that there may be no interval guishing fire by chemical means, deserving of between them and the joists; and the same notice, is the composition prepared by M. Von plaster ought to be spread with a trowel upon the Aken, and which consists of the following ingre- tops of the fillets, and along the sides of that dients:

part of the joists which is between the top of

lbs. the fillets and the upper edge of the joists. "To Burnt alum

3

fill

up the intervals between the joists that supGreen vitriol in powder

4 port the floor, short pieces of common laths, Red ochre, pulverized

2 whose length is equal to the width of these inPotter's clay, finely pounded and sifted 20 tervals, should be laid in the contrary direction Water

. 63 to the joists, and close together in a row, so as

to touch one another; their ends must rest upon Dr. Hales proposes to check the progress of the fillets, and they ought to be well bedded in fires by covering the floors with earth. The pro- the rough plaster, but not fastened with nails. posal is founded on an experiment which he They must then be covered with one thick coat made with a fire board half an inch thick, part of the rough plaster, which is to be spread over of which he covered with an inch depth of them to the level of the tops of the joists: and damp garden mould, and then lighted a fire on

in a day or two this plaster should be troweled the surface of the mould; though the fire was over close to the sides of the joists, without kept up by blowing, it was two hours before the covering the tops of the joists with it. board was burnt through and the earth prevented the method of double-flooring, the fillets and it from Aaming. The thicker the earth is laid short pieces of laths are applied in the manner on the floors, the better; however, Dr. Hales already described ; but the coat of rough plaster apprehends that the depth of an inch will gene- ought to be little more than half as thick as that

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in the former method. Whilst this rough plas- of this kind are generally unsightly, and not apter is laid on, some more of the short pieces of plicable to any use except that, for which they laths above-mentioned must be laid in the inter were primarily intended; the natural consevals between the joists upon the first coat, and quence of which is, that they are put out of the be dipped deep in it. They should be laid as way and neglected, so that when wanted on a close as possible to each other, and the same di- sudden emergency, they would probably not be rection with the first layer of short laths. Over forthcoming. It is this consideration which has this second layer of short laths there must be induced Mr. Witty to convert his fire-escape into spread another coat of rough plaster, which an elegant and convenient article of furniture, the should be troweled level with the top of the natural position of which would be the recess of a joists without rising above them. The rough window in a bed-chamber, which is the precise plaster may be made of coarse lime and hair; place, where, in case of fire, it would be most or, instead of hair, hay chopped to about three conveniently used. inches in length may be substituted with advan It consists of a chair capable of having its seattage. One measure of common rough sand, part lifted through the window, at any time; the two measures of slaked lime, and three mea- top which contains the roller cạtches withinside sures of chopped hay, will form in general a the sill of the window-frame, the chair instantly very good proportion, when sufficiently beat up adjusts itself on the same principle as the paintogether in 'the manner of common

ter's machine, and requires no kind of fixing or The hay should be put in after the two other fastening whatever, but is perfectly ready for a ingredients are well beat up together with water. person to descend, which may be done from a This plaster should be made stiff; and, when the four-story window to the street in half a minute flooring boards are required to be laid down from the time of getting out of bed. The bag is Fery soon, a fourth or fifth part of quicklime kept open by being made fast to a strong frame, in powder, formed by dropping a small quantity and well secured by girth-web, which passes of water on the limestone a little while before under it, and by which it hangs; these webs go it is used, and well mixed with this rough plas- over rollers, and pass on to the end of the upper ter, will canse it to dry very fast. If any cracks roller, where a sufficient quantity is coiled round appear in the rough plaster work near the joists to reach from the top of the house to the bottom. when it is thoroughly dry, they ought to be closed When a person gets into the bag, it begins to deby washing them over with a brush wet by scend, and as the web uncoils itself from the putting two measures of quicklime and one of rollers, it causes the flexible rope to wind round common sand in a pail, and stirring the mixture the middle part of the roller; a person within with water till the water becomes of the con the room lays hold of this rope to prevent the sistence of a thin jelly. Before the flooring too rapid descent, and, if that is not enough, the boards are laid, a small quantity of very dry handle of the break or regulator is raised by common sand should be strewed over the plaster him. In case of alarm of fire, take off the seat work, and struck smooth with a hollow rule, and cover by the two arms and throw it entirely moved in the direction of the joists, so that it away from you, pull the chair over towards you may lie rounding between each pair of joists. as it stands, and lift the seat part through the The plaster work and sand should be perfectly window. dry before the boards are laid, for fear of the To rescue a family, one person will manage it dry rot. The method of under-flooring may be for the whole. On putting the machine out, a successfully applied to a wooden stair-case; rope immediately falls, which winds on the but no sand is to be laid upon the rough plaster roller as the bag descends; when one person is work. The method of extra-lathing may be down, the rope must be redrawn and the bag applied to ceiling joists, to sloping roofs, and ascends for another, or two or three children may to wooden partitions.

3. The third method, descend at once; each descent occupying about which is that of inter-securing, is very similar one minute, a family of twelve persons may be to that of under-flooring ; but no sand is after- saved in as many minutes: at the right-hand wards to be laid upon it

. Inter-securing is end of the roller is the break or regulator, by applicable to the same parts of a building as the merely lifting which any person may prevent method of extra-lathing, but it is seldom neces- the too rapid descent of a great weight; but this sary.

is not of importance, as the same may be done Fire-Escape. The best mode of constructing by the rope, but not so easily as not affording so an apparatus, capable of furnishing prompt and much purchase on the roller. When all are down efficient aid to persons placed in any exposed but the person who conducts the machine, he will and insulated situation, during the progress of enter the bag taking the rope with him and this destructive element, may be considered as a letting himself down; after which, should any matter of considerable importance, though it is one appear at the window; he may, while in the one that has hitherto been little attended to. We street, draw the bag up to them and let them propose, in the present article, to furnish a brief down; should the bag ever be destroyed after outline of the various contrivances that have been the first ascent, the rope (which is a patent one)

may be thrown down, and, being held by a perMr. Witty's fire-escape resembles, when folded son at a distance, a descent may be attempted up, a small chair, being furnished with arms, hy sliding down it; and, should both fail, in the cushions, and a cover, all of which are easily greatest extremity four persons might sit on the moveable, and have nothing to do with the ma machine outside the window, thus affording time chine when used as a fire-escape. Implements to bring fire-ladders, &c., for their relief. VOL. IX.

R

suggested for the purpose.

Mr. Forster of Walthamstow, has contrived a loosely buckled round the chest, and then the very ingenious fire-escape. It was originally rope which is on the roller is to be thrown out suggested by Mr. Maseres, and an account of of the window on the ground. Now, all being the invention was published in the Philosophical ready for descending, the person is to get out of Magazine. It consists of a suspension-iron, the window, grasping tight, with one or with which is formed like the ramhead commonly both hands, the rope at some convenient part, used for slinging goods from warehouses, with taking especial care not to meddle with the susthis difference, however, that the bottom hooks pension iron until quite out of the window; after are turned up close to the upright part, to form which the rope below the regulator is to be laid two close rings or eyes: the length of this iron hold of with the right hand, and to be let to run is about four inches and a half; the thickness of through the holes as fast as there may be occathe iron out of which it is hammered is about sion; for which purpose, if necessary, it may be half an inch. The rope is made of fax, and easily slipped out of the open hole; it will then platted in a peculiar manner. It should be about have the check of only three holes: if the mothree-eighths of an inch in diameter, and must tion is wanted to be retarded, the rope is to be be somewhat more than twice the height of the put into the notch at the upper part of the reguwindow from the ground. The regulator is an lator. When one person has descended, and there oblong piece of beech wood, six inches and a is a necessity for a second immediately to follow, half in length, three inches and a quarter broad, the union strap is to be unbuckled, when the reand about seven-eighths of an inch thick: in this gulator will be separated from the upper belt: there are four holes pierced for the rope to pass the belts may then be very easily drawn up, through; one of these is open at the side: there having the friction of the suspension-iron only

, is also a notch at the top of this piece of wood, and the person above is to put on the belts as and an oblong hole about seven-eighths of an the other did, and is to be let down gradually, inch from the bottom. The upper bolt is a stout partly by the one below, and partly by managing leathern strap, about four feet three inches long the rope as the first did; in this case great care and one and a half broad, with a buckle to it. must be taken, as the check occasioned by the The lower belt is a strap of the same sort as the regulator is gone. It is not easy to lay down other; but the end, after being put through the exact rules for what number of holes the rope buckle, is sewed down: this is for the purpose of must pass through, as this must vary according security, in case the tongue of the buckle shonld to the weight of the person, and other circumby accident break. The union strap, so called stances. It would be well, before the person gets from its connecting the regulator to the other out of the window, to examine, first, whether the parts of the machine, is leathern, and is about a suspension-iron is in the hook, this is absolutely foot and a half long and an inch and a quarter necessary : then, that the three buckles are fast, broad : it has, like the others, a buckle to it. It the two knots tied, and that the rope is in the is stained black, which distinguishes it from the hole of the regulator which has the opening. other leathern straps. The method of putting Great care must be taken that there is not any together all these parts of the machine is, first to impediment to the free running of the rope; for pass one end of the rope through the holes in which the wall of the house must be examined, the regulator, then through the two lower rings and any nails or hooks which may chance to be of the suspension-iron: the upper belt is then to there removed; also iron scrapers, and every be passed through a doubling of the union strap; thing wherein the rope may be likely to catch. after which the rope is to be tied to that belt, and Mr. Davis's fire-escape is calculated for the the knot secured by a string from slipping (which use of a parish; its principle consists in three string is to pass through two small holes in the ladders applied to each other by four clasp irons leather); and at a foot below the rope is to be on the top of each of the two lowermost, which tied to the lower belt in like manner. Next the are so contrived that each ladder may slide into union strap is to be put through the oblong hole the one beneath it; on the top of the lowerinost in the regulator, and buckled; by which the ladder, two pulleys are fixed on the inside, over upper belt and the regulator will be connected. which two ropes pass. The ropes are made fast The other end of the rope may be kept wound to the bottom of the middle one on each side in on a wooden roller, to prevent it from getting a proper direction with the pulleys on the top. entangled. Persons who purchase these ma The upper ladder is attached to the middle one chines should have a very strong iron 'hook, with in the same manner, and on the top it carries a spring catch, fixed to some secure part of the two horn-pieces, made of iron, and turned off at window-frame, or elsewhere; on this hook the each end similar to two horns which are four suspension iron is to be hung by the upper ring, feet wide; their ends are sharp, to pitch on each when any one wishes to descend from the win- side of a window, and with their points hold the dow. The next operation is to step into the lower ladders steady. The three ladders when shut belt with both feet, and draw it up sufficiently down are about fifteen feet in height. They are high, so as to form a kind of swing to sit in; the placed perpendicularly in the middle of a framed part of the strap which is through the buckle is carriage of nine feet six inches long, and five feet to be laid hold of with the left hand; and the six inches wide, mounted upon four wheels. On buckle, with the right hand, is to be slipped to each side of the carriage a windlass is placed, its proper place, according to the size of the and, by turning it, the ladders may be wound out person: the tongue is then to be put into one of from their standing height of fifteen feet to forty. the holes, as in buckling common straps. After Over this windlass is a screw turned by a winch, this is done, the upper belt is to be somewhat by turning which the ladders may be inclined

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