nicely-stained and varnished margins you need trouble no further. Without doubt, if you are determined to banish dust from your floors, you can do so more easily when they are treated in this way than if covered all over.

If you have a friend you fear is not very cleanly, do not advise them this as a cure, for alone it cannot be so.

These remarks concerning carpets and curtains will, of course, apply throughout your houses. But I do not know what more to say than I have done concerning the other articles of furniture, unless you will permit me to use again the argument I used when speaking of colour, that those combinations which are subtle and true in their harmonies have a more healthy effect upon the mind than the heavy unsuitable ones. So, I can conceive, the beautiful form that brings the imagination into play, and gives room for thought, must affect the physical health through the mental. Certainly couches and chairs that are comfortable and restful, so being really artistic by rightly fulfilling their destiny, are more conducive to good health than others designed without this consideration. The irritable temper is less often roused if its surroundings, the articles of daily use, are convenient to their varied purposes. Designers should think more of this and be less haunted with the desire to produce something novel, and remember that "Construction should be decorated, decoration should never be purposely constructed," and also "That which is beautiful is true; that which is true must be beautiful." And then our shop windows and houses will cease the display of tawdry, comfortless, and useless rubbish with which they are filled to-day.

HEATING, LIGHTING, AND VENTILATION.

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BY JOHN NEWTON, Esq., M. INST. C. E.

WHEN I undertook, a few weeks ago, to prepare a paper with the above heading, I was not aware that the subject had already been so ably dealt with by others, and my feeling on discovering this was to be relieved, if possible, of the obligation to read it. But on looking over the lecture delivered by Mr. John Angell, F.C.S., in the Session 1882-3, I came upon this remark— "The object of the Sanitary Association in presenting annually to the public these additional series of lectures is, however, so to extend Sanitary Knowledge, and so to impress it on the minds of their fellow citizens, by continual repetition, just as the continued dropping of water wears away the hardest stone, 'that it shall become so familiar and practicable as to become the daily guide of their lives."" Entertaining as I do a high opinion of the Association, and a thorough appreciation of its work, I at once determined to follow in the footsteps of others, and to aid, as far as I am able, however imperfectly that may be, the objects they have in view.

Dr. Ransome commenced the first lecture of the present series by saying that it is intended to make "the dwelling-house the centre around which all our discourses are to play." He and others have already discoursed upon its "Site and Soil," its "Drainage," the requisite "Plans and Sections," its "Foundations and Materials," and "Plumbing," &c., and it has fallen to my lot now to discuss the Heating, Lighting, and Ventilation of the

structure.

Whether we live in a cottage or a mansion, efficiency in these matters is essential to our health and comfort, and important, moreover, on the ground of cost, direct and indirect. In the following remarks my endeavour will be to show how efficiency can be obtained in the most economical and simple manner. new principle will be enunciated-in fact, it is sometimes said "there is nothing new under the sun," and that "what is new is not true, and what is true is not new"—and all that will be

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attempted will be a description of the systems already before the public, or the application of well-known principles to practice.

We will first consider the heating of the house, but in doing this we must keep in view the method of lighting, because lighting, except when done by electricity, implies also heating; ventilation then follows, being intimately associated with, and in fact rendered necessary by, both heating and lighting.

The open fire-grate is the commonest and most favourite mode of heating adopted in our English homes; but we have also the close stove, the gas stove, hot water pipes, and hot air.

The common grate warms mainly by radiation—that is, by rays of heat emitted from the burning fuel which strike objects which impede their progress, and these objects, according to their nature, absorb more or less of heat, which is afterwards communicated to the surrounding atmosphere. The close stoves and hot water pipes, on the contrary, heat principally by convection—that is, they warm the air which touches them, and this, by its levity and tendency to diffusion, spreads itself through the apartment. In the first, we have warm walls and furniture, with a cool atmosphere, and in the second, cold walls and warm air. A little of both is desirable, but radiant heat is undoubtedly preferable to heat by convection.

The sources of heat are primarily the sun and the earth itself, but secondarily, mechanical motion and chemical affinity. The latter is the source we have to deal with in heating our dwellings, and is described by chemists as “the chemical and atomic union of the combustible with atmospheric oxygen," to effect which we must have the required quantity of air and "the proper mode of bringing it into contact and action with the combustible." Without oxygen nothing will burn. A common mode of illustrating this is to place a lighted taper under a bell glass, and it will be found in a few moments that the flame sickens and dies out altogether. We have then the combustible only left, the oxygen having amalgamated with the carbon of the combustible and formed carbonic acid gas.

The amount of heat evolved in the process of combustion depends to a great extent upon the quantity of oxygen combining with the combustible. Thus, a lighted taper, or a piece of iron wire even, heated to redness, and plunged into pure oxygen burns intensely as long as the oxygen lasts, far more so than in the case of a taper burning in ordinary atmospheric air, only about twenty per cent of which is oxygen.

It will thus be seen that to generate heat we must have oxygen atomically mixed with the carbon contained in the coal or other combustible employed, and as air, when heated, becomes expanded, it is manifest that a current of cold air will supply a greater quantity of oxygen than a similar current if heated and consequently expanded.

Fires usually burn more brightly in winter than in summer, and the sun's rays will sometimes even extinguish a fire.

An important point to be considered is the flue for carrying off the products of combustion. It is scarcely necessary to observe that these gases are injurious to health. Taking the bell glass illustration again, it will be found that although the air in the glass was perfectly pure at first, it soon became changed in character. The flame expires, it is unfit for respiration, and consequently animal life could not exist therein. The change is two-fold-we take away a vital element and substitute a poison.

The action of the flue or chimney is very simple. Gases and vapours expand in proportion to their increments of heat, the expansion being equal toth part of the volume at zero for each degree of heat added. Thus, if 460 measures of air at o° be raised to 40°, the space occupied will be enlarged to 500, and if raised to 60° it will be increased to 520. Suppose the average temperature inside a flue to be 60° and outside 40°, the height of the chimney being 26 feet, then as 520: 26:: 500: 25 feet-that is, a column of air 25 feet outside will equal in weight 26 feet inside; in other words, we have a column of air, or pressure, of one foot outside creating an upward current of the heated gases inside the chimney.

It is easy to ascertain the velocity of the ascending current from a well-known formula applicable likewise to falling bodies, namely, √h x 8, which in this case becomes 8 feet per second, or 480 feet per minute; it is usual in practice to make an allowance of at least 25 per cent for friction, irregularities in the flues, &c., but it is not at all uncommon to have an actual velocity of 10 to 12 feet per second, which, with a flue 14-inches x 9-inches, means 30,000 to 40,000 cubic feet per hour abstracted from the apartment.

Chimneys sometimes overpower each other—that is, a flue from one fire place will be fed from a down draught in some other. In some cases this arises from unequal height of chimney shafts; in others it is caused by a larger fire in one room than another, and sometimes it is due to the proximity of higher buildings, over

which the winds sweep, and fall as it were upon the top of the lower chimney and down it into the rooms of the house. The first essential is to provide each with a sufficient and independent supply of air, so as to render it unnecessary for one ever to rob another, and if the stack is too low, and cannot be sufficiently raised, we must apply a suitable cowl, many good designs for which are before the public, such as Boyle's, Banner's, Ellison's, and others. Mr. J. Brierley, C.E., has lately patented a chimney terminal which promises to be efficient, more especially in cases of down draughts, consisting of a wire-work cap, reminding us somewhat of the Davy lamp. Its simplicity and economy are also greatly in its favour.

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A A-Are three or four small brackets to support wire-work caps. B B-Are the double wire-work caps, space between them 1 inch. CC-Annular space between flue and wire-work caps, about 1 inch.

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We have now arrived at this point, that there must be a sufficiency of air to effect combustion, and sufficient means of exit for the products of that combustion.