than for the architect. The Galton ventilating air stove is largely used in hospitals and infirmaries. The Manchester grate, manufactured by E. H. Shorland, of Manchester, for houses, schools, hospitals, asylums, &c., is used by the Bank of England at its branch establishments. It is called a patent first class smoke consuming and warm air generating grate. Heat is not only given off by radiation, but warm air can be supplied to rooms above or adjoining the one in which the grate is fixed; in 1882 it was stated to possess nearly 80 per cent. more heat-giving properties, and to be nearly 100 per cent. better as a smoke consuming grate, than others tested at the time. The Wharncliffe patent warm air ventilating grate. Grundy's patent warm air ventilating fire grate, in which the heating surface is stated to be greater than any other. Reeve, Ratcliffe & Co.'s Cosy grate is the only open fireplace in which the products of combustion are filtered through a red-hot wasteless purifier, and therefore is a smoke consuming economical grate. 2279e. II. The varieties of close stoves are very numerous, but the principle upon which they depend for their efficiency is in all cases nearly the same. This may be stated to be the heating of metal plates by the combustion of fuel in actual contact with them. The quantity of heating surface in the room wherein the stove is placed can be materially increased, and nearly the full effects of the heated products from the fuel obtained, by lengthening the smoke flue; but the longer the flue the less is the draught of the fire, which is further lessened by its becoming choked with soot; thus a 3-inch pipe attached to a small stove, burning coal and in constant use, has been found so completely filled up with soot in the course of a week that a stick half an inch in diameter could scarcely be passed through the hole left in the centre. The now common American cooking-stoves are on this principle. The principle of the Arnott stove is that of consuming the peculiar fuel recommended for its use very slowly, and the detention of the heat in the stove. The addition of a descending flue to some of these stoves is an advantage when it is desired to place the stove in the middle of a shop or warehouse. Franklin's calorifere, or the vase stove, having a descending flue, was formerly much used. When this system has been adapted to flues carried under a stone floor (after the Chinese fashion), it has been found to warm most efficiently an office and principal staircase with a mere handful of fire, at a cost of about 30s., while by another apparatus the cost was 18. (Beaumont, Hints for preventing Damage by Fire, 1835.) This is an elaboration of the common method of warming greenhouses by the brick or smoke flue, through which the smoke and flame travels from the furnace. A fire-clay casing for the fuel is also combined with some of them. Haden's apparatus has been mentioned (par. 2278/.) for warming large buildings; and equally efficient is that by Grundy, which is also much used for churches and large buildings. The Tortoise stove is a late production for a small room.

Gas stoves are of various sorts. There are many of iron make, which render the air unwholesome. Wessel's patent heat dissemin tor (about 1850), made of copper, has proved of value even in rooms kept closed. Ritchie & Co.'s Lux-calor new patent apparatus for heating and ventilating large buildings by gas, requires no flue, and has no smoke nor smell; the principal parts are made of copper. It was much used in the Bank of England. S. Clark & Co.'s patent Syphon stove is a condensing gas heating, similar in principle.

2279f. The high temperature stoves, such as the cokles, the Strutt or Belper stove, the Sylvester's, and others, all used for warming extensive spaces, consist of large metal plates or surfaces of brick or stone, heated in or by a furnace or fire, the air to be warmed being caused to impinge upon or pass between them, and then carried along in tubes to the several rooms or floors where the heat is required. The hot air pipe furnace is used for the same purposes, whereby the flame and smoke passes along the inside of the tubes. In Davison and Symington's furnace for obtaining heated currents of air for manufacturing purposes, the cold or fresh air is driven by a fan at a great velocity through the pipes, which are placed in contact with the flames. Any cessation of the blower may be expected to cause material injury to the pipes.

22799. A writer explaining the common American system of warming houses by hot air, says that the whole comfort of the result depends upon how the atmospheric air is heated. The various plans are effected by a furnace, from the dome of which pipes are coiled and twisted about so as to gain the utmost possible radiating surface, and the air is brought in contact with them as it passes through the chamber. To get cheaply a great amount of heat, the castings are made very thin, the air chambers and hot air pipes small; whereby the result is, that a hot desiccated poisonous air is discharged into the room, injurious to the lungs, and causing headaches. Where the air chamber, however, is large, the furnace very wide and shallow, and its dome high, with the radiating surface largely extended, and the external cold air shaft spacious, this mode of heating is excellent. No apparatus of its kind ever surpassed the old Boston furnace, first invented by Chilson, and since so greatly improved by his successor in New York. In the "Boynton furnace," as it is called, the shaft bringing in the cold air is very large, frequently 4 feet wide and 2 feet or more deep, and the air chamber and tin pipes therefrom are also of considerable In the air-chamber a small jet of water is kept playing to restore the natural moisture to the air. Anthracite coal is used, a ton of which, for an ordinary house,

size.

would be a sufficient supply for nearly three weeks. No other fires, except that of the kitchen range, is usually seen in houses possessing this apparatus. (Builder, xxiii. 582.) The heating of houses by warm air, and the substitution of gas for general heating and cooking purposes, advocated by a method adopted by Mr. A. E Fletcher, was considered in the Journals of Jan. 1888 A brick chamber in the basement contains a stove in which coke is burnt; air is brought in from the outside, and then conveyed by means of pipes to the entrance-hall and ground-floor rooms, thus warming the whole house, with the result of a considerable economy of fuel. Then asbestos gas fires were used in the rooms, and gas cooking ranges in the kitchen, with great avantages of le-s dust, cleaning grates, lighting fires, &c. This is not all new (see par. 2279g). Many persons have for years found the advantage of the hall and staircase being warmed, if not carried to too great a heat, but only as an auxiliary to open fires, and the upper floor kept ventilated. Gas fires are not to be depended upon as successful. Gas cooking stoves are useful in many cases, but much depends on the domestic even then.

2279h. III. The circulation of hot water in pipes is caused by the unequal density of the fluid, arising from the difference of temperature in the ascending and descending columns of water connected with the heating reservoir; and its velocity is governed by the height of the columns; Bramah, in appendix to Tredgold, Heating. A boiler (the "conical" boiler is consid-red the best form by some manufacturers, while others prefer the "saddle-back") heats the water, which, as it becomes warmed, rises and passes out through the flow pipes; these are laid at a very slight inclination, to assist the current. When the water has arrived at its furthest extent, it enters what are termed the return pipes, on its way back to the boiler, which it enters at the lowest part, to be re-heated, to rise, flow, and return as long as a fire is kept up. A rough calculation has been made that for every 50 feet of 4-inch pipe 1 square foot of boiler surface is required. The self supplying cistern and its expansion box must be placed somewhat above the highest level at which the hot water is desired to rise, yet not so high that the pressure in the pipes will affect their joints. It should be covered, and have a pipe to allow the vapour or steam produced by over-heating to escape into the external atmosphere. With this, the low temperature system, the heat of 212°, or that of boiling water, cannot be exceeded. Jeffrey's patent Radiator, for hot water or steam, in single or double loops or coils, is ornamental.

22791. IV. The high temperature system was introduced by Perkins, and is frequently called by his name. Water is placed in a coil and range of piping of small diameter, hermetically closed, so as to prevent all communication with the external atmosphere. A coil, being at least one-sixth of the whole piping, is heated by the action of the fire in immediate contact with it, by which means the temperature of the water in it can be raised easily to 300° or 400°; but then the same objection applies to the air warmed by pipes so heated as to that from high temperature stoves. As water expands with heat, allowance has to be made by the addition, at the highest point, of a larger tube to receive the surplus, which varies from 10 to 12 feet per cent.; one-tenth of the spice of piping may thus be allowed for expansion. After the pipes are fixed, they are very carefully filled with water, so as to expel all air, through a filling tube situated at the bottom of the expansion tube, and when sufficiently full they are hermetically closed. The danger to be chiefly apprehended from this apparatus is that, if leakage takes place, the loss of water causes red-hot vapour to be formed, with the possibility of setting fire to any wood to which it may be attached. There is now no doubt but that wood, subjected to a constant current of greatly heated air, becomes very liable to combustion.

2279k. When heating surfaces of great extent are required to be obtained by the application of hot water or of steam, Walker's system will probably be found to be the most effectual yet introduced. It must be sufficient here to describe it as consisting of a number of small iron blocks, each block having square perforations passing through it for the current of air from the top to the bottom, of very thin metal. The blocks are enclosed in a corresponding periorated iron box, leaving 1 inch for water or steam all round each block, which heats the metal forming the blocks By this very compact arrangement -160 feet of heating surface may be obtained in a box measuring not more than 2 feet cube. 22791. The rules for finding the area of hot water pipes for any sized apartment are in all respects essentially the same as will be given for steam, excepting the mean temperature of the pipes: for steam-pipes 200° is given; but 140° to 150° may be taken as that of low temperature hot-water pipes. From data obtained by Hood, Practical Treatise, 3rd edit., 1850, it appears that water in a pipe of 4 inches diameter loses 851 of a degree of heat per minute, when the excess of its temperature over that of the surrounding air is 125°; and also that, under the same condition, one foot of such a pipe will heat 222 cubic feet of air one degree in the same time; whence he deduces the following rule:-Multiply 125 by the difference between the maximum proposed temp rature of the room and that of the external air, and divide this product by the difference between the temperature of the pipes and that proposed for the room; then the quotient is to be multiplied by the number of cubic feet of air to be warmed per minute; and the product,

f

divided by 222, will give the number of feet, in length of pipe of 4 inches diameter, required to produce the same eff ct; this length is to be multiplied by 1.33 or by 2, for equivalent lengths of pipes respectively 3 and 2 inches in diameter.

2279m. In making arrangements for heating by steam, we need not describe the con struction of the furnace and boiler, or of the chimney, matters which are perhaps better arranged by the engineer fitting up the apparatus, as steam for warming purposes is rarely adopted except where waste steam can be brought into use, as in factories and workshops using steam power. The thicker the metal of the pipes the better for greenhouses and such like places; for buildings, the thinner the better, consistent with strength; say about ths of an inch in thickness. Provision must be made for the expansion of pipes, both for steam and water, of about one-eighth of an inch for every 10 feet of length. The pipes should be placed near the floor, and as close as possible to the apertures for the admission of fresh air. The pipes should be laid with an inclination to the boiler, so that condensed water from the steam shall be returned to it; and they should be carried at once to the highest part of the building and descend to the lowest.

2279n. To form some idea of the requisite area of piping for any desired buildings, the quantity of cubic feet of air required per minute must first be ascertained. In order to ascertain this, attention must be given to the loss of heat by ventilation, and the direct influence of cold external walls, glass windows, &c. From the first cause there will be a loss of heat proportioned to the quantity of the air withdrawn per minute: if 4 cubic feet are supplied to each individual per minute, then "there will be for each individual 4 cubic feet of air conveying off a quantity of heat equal to the difference between the heat of the external air and that of the room." Thus, if the heat of the room be 70° and that of the external air 50°, then the withdrawal of 4 cubic feet of air per minute must lead off a quantity of heat equal to the differences between 70° and 50°, or 20°. From the second cause there will also be a loss, as heat is transmitted very quickly through glass; the quantity of air cooled in a given time being simply proportional to the surface of the glass exposed to the external air, and, consequently, will be constant, whatever variation of temperature may take place. The rule given by Tredgold, § 67, is as follows:-"If the area of the sur:ace of glass be multiplied by 15, the product will be the number of cubic feet of air per minute which will be cooled from the temperature of the room to that of the external air;" and to this loss will also be added that arising from each door and window (independently of occasionally opening and shutting the former); this was calculated by the same author, § 65, to be equivalent to il cubic feet per minute, the difference of temperature between the internal and external atmosphere being 60°.

22790. From a combination of these circumstances, assisted by various experiments, Tredgold, § 68, deduced the following rule:-If the number of people the room is intended to contain be multiplied by 4 (or the quantity of air allowed per minute), and added to 11 times the number of external windows and doors (as 11 cubic feet of air is passed through each per minute on an average), added to 1 times the area in feet of the glass exposed to the external air, the sum obtained will be the quantity, in cubic feet, to be warmed per minute. The next operation is to find the area or surface of piping which will warm this quantity of air. The mean temperature of a steam pipe at the ordinary pressure is 200°. The temperature of the air supplying ventilation is to be known at the extreme case of cold, which for the day may be taken at 30°, but for the night may be assumed in this country at zero of Fahrenheit's thermometer; the temperature to be maintained at the same season of co d is also to be settled. Then, Tredgold, § 44, gives the following rule:- Multiply the cubic feet per minute of air to be heated, to supply the ventilation and loss of heat, by the difference between the temperature the room is to be kept at and that of the external air, in degrees of the thermometer, and divide the product by 21 times the difference between 200 and the temperature of the room. This quotient will give the quantity of surface of cast iron steam pipe that will be sufficient to maintain the room at the required temperature. According to Dr. Arnott, 1 foot of superficies of heating surface is required for every 6 feet of glass; the same for every 120 feet of wall, roof, and ceiling; and an equivalent quantity for every 6 cubic feet of air withdrawn from the apartment by ventilation per minute. (Tomlinson, p. 124.)

2279p. "The Metropolitan Building Act, 1855," requires that:-I. The floor under every oven or stove used for the purpose of trade or manufacture, and the floor around the same for the space of 18 inches, shall be formed of materials of an incombustible and non-conducting nature; II. No pipe for conveying smoke, heated air, steam, or hot water, shall be fixed against any building on the face next to any street, alley, mews, or public way; (III. A pipe for conveying hot water, or steam, at low pressures is now not required to be kept clear of combustible materials); IV. No pipe for conveying hot water shall be placed nearer than three inches to any combustible material; and V. No pipe for conveying smoke or other products of combustion shall be fixed nearer than nine inches to any combustible material; with a penalty not exceeding 201. for non-compliance.

SECT. XV.

SPECIFICATIONS.

2280. The importance of an accurate specification or description of the materials and work to be used and performed in the execution of a building, is almost as great as the preparation of the designs for it. The frequent cost of works above the estimated sum, and its freedom from extra charges on winding up the accounts, will mainly depend on the clearness, fulness, and accuracy of the specifications; though it is but justice to the architect to state that extras arise almost as often from the caprice or change of mind of his employer during the progress of the work, as from the neglect of the architect in making the specification. A specification should be made in all cases of new designs, additions, or alterations in reference to designs, which, the more they are given in working drawings by the architect, the better will it be for his employer, no less than for the artificer.

2280a. When the drawings have been brought to suit the client's tastes and requirements, the architect commences to prepare the working plans and details. Before these are completed, he should take up the specification. The primary and main object of a specification, is to give, fully and clearly, all necessary and useful written explanations and instructions for the execution of the work, and for making due preparations for the effecting of a definite and clear bargain between the person or company accepting an offer and the contractor offering to execute the work.

2280h. To write out a document fulfilling all these requirements, going into every particular, and describing fully and accurately each different part of the work, must naturally cause a lengthened document. But a line must be drawn between running to an almost absurd length and being too brief. The former may occasionally cause the specification to be neglected, as the builder or his foreman has seldom the time to refer often to it. The rotation of the various paragraphs is a very important matter. It was formerly, and is now, much the custom to divide the specification into trades, which system arose when separate contracts were taken for different branches of the work; but at the present day, when it is so general to have one contractor to carry out the entire work, it has occasionally been attempted to write a specification in a form more quickly and easily consulted than by referring to paragraphs in several trades respecting some one single portion of the work.

2280c. Some architects have written the main portion of the details on the drawings themselves, detaching them from the general and specific work, particulars, and conditions; but the drawings are not always at hand to refer to, if there be no "office" on the building.

2280d. In many large towns it has become the custom to relegate this important part of an architect's business, especially of a young one, to a "quantity surveyor." By doing this, he loses that grasp of construction and of details which the preparation of a specification, as of quantities, so greatly helps. The man who originally draws the working plans can with much greater facility write out the specification for the execution of the same than the man who, so to say, has first to learn his lesson. It should bear the impress of the artistic feelings of the designer, which the quantity surveyor can never give it. Each item is usually taken separately, and should be clearly described; simple language should be used, without abbreviations; all such words as proper, properly, sufficient, with others, should be avoided; involved sentences, bad punctuation, and faulty grammar should not appear, and each sentence should bear but one meaning; but, regarding the haste with which specifications have to be drawn up, these are sometimes unavoidable. Sketches made in the margin, of difficult bits of construction, as well as of ornamental details, may be copiously used, especially if the detail drawings are not fully prepared. 2280e. Specifications are now usually lithographed, which saves much trouble and risk in examining each copy that may be required.

2280f. It is advisable that the agreement with the artificer or contractor should be drawn up by the client's solicitor, who, no doubt, will seek the assistance of the architect. 2280g. It is impossible to frame a set of directions which shall be applicable in all cases of buildings. Something like a list or skeleton of the component parts of buildings are given in the following pages, from which the architect may select such as are suitable to the particular case whereon he may be engaged. This is not carried into the repairs and alterations of houses, because, with difference of application, the same system can be carried forward in such cases without difficulty. Chapter III., USE OF MATERIALS, Or PRACTICAL BUILDING, may be consulted for many other details.

2280h. The following pages have been rewritten, condensed, and added to as necessary. A large amount of information as to the manner in which materials are used and put together is contained therein. There are several books on the subject, one of which, Powtner's Comprehensive Specifier, 8vo. 1870, should be on the student's shelf.

22801. Among the Acts of Parliament, &c., to which the attention of the architect and of the builder has to be directed, are the following. Towns and several other places, and the London prishes, &c., have their own local Acts and bye-laws.

Metropolitan Building Act, 1855, 18 & 19 Vict., c. 122. Amendment, 1860, 23 & 24 Vict., c. 52. Amendment, 1869, 32 & 33 Vict., c. 82.

Metropolis Management Act, 1855, c. 120. Amendment, 1862.

Metropolis Management and Building Acts Amendment Act, 1878, 41 & 42 Vict., c. 32. Amendment Act, 1882, 45 Vict, c. 14.

Metropolitan Board of Works, Bye-Laws, after 1878.

Public Health Act, 1875, c. 55.

Knight's Annotated Model Bye-Laws of the Local Government Board, 8vo., 1883, is useful.

GENERALLY.

2280k. The contractor to supply all requisites; to provide all materials, new and of the best quality; to execute and complete in the best and most workmanlike manner all the works set forth in the specification and drawings, to the satisfaction of the architect; to give notices to, and pay fees and charges of all local authorities and officers, as district surveyor, paving board, for hoarding, water, gas, and such like (the rights as to advertising on hoardings to be reserved, or not to be allowed as on some estates, and as to the gravel and sand that may be found on the site); to provide a watchman; to insure from fire in the names of the builder and the client; to provide and maintain on the site an office for the clerk of the works, furnished, and for the custody of the drawings and papers; to afford access for the architect, his representative, clerk of the works, and the client, to the premises; to remove all dirt and rubbish; to sweep out and scour all floors, and clean all glass, and to deliver up the building and premises in a satisfactory state at the conclusion of the works, or at a specified time (it is not very clear when a house is "completed"); as to the use and possession of the documents, and of making copies; to keep on the building a foreman of the works; to carry on the works, and to complete the same; as to unfit workmanship and materials, and works not in accordance with the directions; as to day bills; all disputes to be settled by the architect, or arbitrator agreed to before signing the contract; sum to be allowed for contingent works; as to sureties, time of payments, &c. Besides the above, it would be well to refer to the "Heads of Conditions of Builders' Contracts," sanctioned by the Royal Institute of British Architects, 1882.

EXCAVATOR.

2281. To take down any old buildings and impediments that may be on the site of the new works. If any old materials are to be used again, he is to clean, sort, and stack them for re-using in such parts of the premises as may be directed. The rubbish, as well from these as from any superfluous earth that may come out of the basement and foundations, if not wanted for any purposes, he is to cart away, either wholly, or to such part of the premises as he may be directed, as well as all rubbish that may accumulate in executing the works. To reserve any clay dug out, and to thoroughly burn it with small coal into ballast, as directed. To strip the surface soil to a certain depth. To dig out for basement story (where one is to be), for the foundations, areas, drains, floors, and all other works requisite. To beat down to a solid consistence the ground forming the beds of the trenches for receiving the foundations and walls, and after they are in, he is to fill in and ram down the ground; to level, and to do such other rough groundwork as may be necessary for forming the sectional ground lines shown upon the drawings. To prepare for concrete in foundations. To cover over the ground under paved or tiled floors (except where the tiles are laid on joists) with broken bricks well rammed and grouted with liquid mortar. This layer is to be made of sufficient thickness to receive 6 inches of concrete, which is to be properly rammed and covered with a layer of 2 inches of fine concrete, finished with a level surface. In basements no earth is to be lett nearer than 9 inches to any floor or other timbers, such cavities being by the specification to be filled in with dry lime core. If water cannot be supplied by any public company, a well may have to be provided, as in next section. To leave the ground free from all useless soil or materials. Roadway and Paths. Remove the top soil from the intended lines of the roads; spread over the site a stratum of coarse stone ballast, or of brick rubbish, 12 inches deep; cover the same with coarse gravel, spread, beaten, and rolled down until hard and solid, forming the width with a curve to each side, and rising. . . inches in the middle. The Paths to have a stratum of coarse stone ballast (or burnt brick ballast where such is to be obtained), or of brick rubbish, 4 inches deep; cover the same with 3 inches of fine red gravel, well beaten down and rolled over until solid, and to be formed to a curve rising inches in the centre.